2 8 2 5 2 8 2 5 :; 11/// . 11111 . 11111 . 1.0 I.0 :~ 1111/ . c;.;; 1I111~~ D~ 11111 3.2 - I;,; IIlll3u :: IIIII.:!! 1_ Il~ ," t" f I~ I: Ido ' " 1.1 I-L., .... 11.1 ~~~ 1m 111111.8
111111.25 IIl1i: 1.4 11111 1.6 111111.25 111111.4 111111.6
MICROCOPY RESOLUTION TEST CHART MICROCOPY RESOLUTION TEST CHART NATIONAL BUREAU OF STANDARDS I%j A NAliONAl BurUAlI or S1ANDARDS 19&3 A Technical Bulletin 1'\0.456 December 1934
CNITED STATEE DEPARTMENT OF AGRIC1JLTURE WhSHINGTON, D.C.
LIFE HISTORY OF LUNGWORMS PARASITIC IN SWINE
Br BEN.UJ\n~ SCHWARTZ• •~clli{ir ZIJ070!Iillt, nIHl .JOSEl'H l!l. AUCATA. jl/lliol' zoolo(/ist. ZOO/of/feal. Dir)i.~iOIl. Blirellll of "lMllwl 111-/71/#1'/1
.1"}(' ....). I (:.: .-) {\. -, ... , ... ' '"' CONTENTS " ,.",(J '.,.' ,,:, Pnge Pnge Introduction ______•______....___ •. _ 1 -'Multing of larvae in the intermadinte host... 20 Be"iew of work of pre"ious !nv.-'ti~utors .. , 2 Descriptions oC develo[lmental stngfs oC lung· Technic used In investigation.. ___• __ .•______3 worms in the intermediate host...... 24 Protocols on experimental inCections of l>feta.lro1lggluB tlongaJUII ...... __ ...... 24 earthworms__ . ______•__ ._.....___ ._. _ 5 Choer03lrongulUII pude1ldotectUII._ ...... __ 26 Infections with :A-Ifta.tronu.~tu. etongatuR. 5 J.leta&ironovltU aolmL______.. ______2; Infections with Choe!o.trongul!l8 pudet,· Nnturui infestntions of earthwonns with doteclu&__ ..______. ______• 8 JII' ,gworm Inr.-ae nnd distribution of earth· w .J... ~ns ______.. ______28 InCections with }.[eln8IrongutUII satmL___ 9 fnfections with undetermined species.... 9 Mi~,.~tion of }.Ieta.tronguIUII e/ongaJlI.! nnd Protocols on natural inCestation of oorth· Chotro&tronwlUII pudendotertuB in tbe de worms witll lll!'vae ofswine lunj!Worms ___ • 10 flnith'e host ....__ ••••__...... __ •.• 211 Protocols on experimenta11nlection 01 vnrlous Molting o!larvae in tbe definitive host...... :10 animals with lungworms_____.._.______II Descriptions or early developmental stages Pi~s ..-.-----...-----....___ • ___ • , ..____ • 11 oC lungworms in the definitive bost...... 31 Guinea pigs ___..._._. __ ...... ___ ._.. 13 }.ffla.lronguillfl elongn/m••__••__ ••••••••• 31 Dogs•• _____ •______..__ •__ .._. ______•• 15 Choero,;/rongutuB pudendotecJu.B._ ••__ ...._ :12 OthermammBllan hosts._..______III Definitive hosts of swine lungworms other Hatching of eggs snd longevity of artificially than the pig...... __ ••__ ...______34 hutched lIu'voo ...._..______: ______.:_ 16 Symptoms and lesions a'lSociated with swlne Species of earthworms in which swine lung· lungworm inCestatlons _____ . ______... ~~ worm larvae developed..______.. _____ Ii Summary and conclusions______.. MIJlTI1t1on of swine lungworms in the inter· Liternture <:ited. ______...... ______• 40 mediate h05t. ______._.______....___• 18
INTRODUCTION The adult nematodes pnrasitic in the lungs of swine comprise 2 closely related genera. Meta.~tr·ong.ll7'U8 and Ohoero8t:rongylu~, and 3 species, namely, M: elongatuB, M. saMni, and C. pudendotectus. These nematodes belong to the family Metastrongylidae, the mem bers of which, so far as is kno'wn, are parasitic in the respiratory and circulatory systems of mammals. The metastrongyles which parasitize domesticated animals are of considerable medical interest. and of unquestiomible economic importance. They present for solu tion problems in livestock sanitation which must await the results of fnrther investigations elucidating the life histories of the species concerned. Rational ('ontrol measures for th~se, as well as for all other zooparasites, must be bllsed on precise information regarding essential facts in the life hii:itories. Such information for swine lungworms is presented in this bulletill. 1 ",p'V"_ .,'..-'~' ~"~_~ •• (j
TECHNICAL 'BULLETIN 456, U. S. DEPT. OF AGRICULTURE " , 2 REVIEW OF WORK OF PREVIOUS INVESTIGATORS Up to 1929 little was known of the life history of the species of lungworms which occur in domestic !';wine. Leuckart (8, 1). g)~ in 1876 expressed the opinion that the species of swine lungworm now known as M etasf1'onqylus elongat~(8 was a heteroxenou8 nema . tode, having its intermediate stage' in an invertebrate, pl'obably an insect or a $nail. Accord~ng to Alessandrini (1, lJ. 479), Cobbol(l shared Leuckart's view with regard to the heteroxenolls nature of swine lungworms and consiaert.~d earthwol'llls as the probable inter mediate hosts. The followin~ iR a rather free translation of the Htatement made by Alessandrini. If the Sllll)l()!';itioll of Cohbold call be ('()(Ifirmell. the life eyc'le woulll bt' yerr l'illlple; (he C';,i';:' and lal:va(~ that are elilllina tell while the sick flllimuis arc t'oughillg, would reach the b'1'OUnU, where the~' would I)l> cngulfeu l~' earth worms, In the Rtomaeh, illtt'Htine, or tifisueR of the:';(' WOI'mil the lal''I'fle would cOlltinue their (]t~'I'elopment and, eliminated to the ontsic1e with the t'xcretu of earthworm!;, could illf('sl other :lI1illlaifi, Howeyer, neither I..{!uckurt 1101' Cobhold presented proof to sub stantifl,te his hypothesis. 'Work carried out in th" Zoological Divi sion of this Bureau by Hansom, as I'eported by Mohler in 1920 (11), and by Schwartz ~ lee~2 independently of each other, ehowed fairly conclusively that lungworms failed to develop in swille when the embryonated eggs or the larvae which hatch in vitro from the eggs taken fr0111 'the uterus were administered to presumably susceptible pigs, observations which 'were confirmed later by Hobmaier and Hobmaier (5), These results pointed to tl1e likelihood of an intermediat~ host being involved in the life cycle of these parasites. Von Linden ancl Zenneck (9) in 1915 anel Zebrowski (13, 1(J) in 1922 and 1925 reported that swine lungworms had a life~ cycle which did not involve an intermediate host. Von Linden and Zpn neck investigated the life histories of several species of lungworms, including one of the species which occurs in swine, this species being designated by these investigators as Strongylus l}aradomu,~, a name which is how re~arde~l as a. synonym of JJIefa8h'ollgyl1J,s elon[Jatu.~. 'Vhether these lDvesbgators actually worked with M. elongatus or with one of the other species of swine lungworms, or with a mixture of species, cannot be determined from data. given in their paper. They report, however, thnt the eggs and larvae of .. lungworms obtnined from wild hogs deVeloped in sterilized soil into free-living individuals showinO' sex differentintion, nnd that these ma:intained themselves as t'ee-living nemnto(le!-l for several generations, An examination of Von Linden and Zenneck's illustrations shows that whereas those of the egg and first-stage larva nre unquestionabl~r figures of, a species of swine lungworm, those of the Rupposed free living generation are figures of nematodes not known to be parnsitic in animals and involve apparently more than one species j one of tIl(: species in question appen rs to belong to the genus Rhabditis, It is clear that Zebrowski n]so was dealing at. least in pal't with larvae of free-living nematodes, a supposition well supported by an
~ Itulle numbers In !lllr(,·"thl'sp.~ rl'("\' to Lit l'rlltUl'C Cltell, (I, 40, • UnpubliRhed datn. LIFE HISTORY OF LUNGWOHl\IS PARASITIO IN
examination of his figures and by his account of the free-living stage of the supposed parasites. It is interesting to note, however, that Zebrowski (15) considered the possibility that swine lungworms might require an intermediate host and that he even exposed earth worms to an experimental infection with " larY~Je in different stages of development." His results were inconclusive but he found nematode larvae in earthworms. In 1929 Hobmaier and H::>bmaier (5, 6) published the l'esults of their investigations on the life history of two speci~s of swine lung worms, Meta.s[?·ongyZws elongahlB and O. 'Pu.delldotect1M]~ and in criminatecl earthworms, species not well c1efinec1,3 as intermediat(' hosts. Briefly, these investigators noted one molt in the course of the development of the larvae in the wall of the esophagus and in the hearts of earthworms, the infective stage being attainC(l follOwing this molt. They demonsrrated, moreover, that pigs could be experi mentallv infected with these two species as a result of ingestin~ eartI1WOl'l11S harboring the infective stage of the parasites. The, e investigators noted also only one molt in the course of the develop ment of lungworms in the definitive host. Their work, so far as the mode of transmission of lungworms to swine was C'onc(,l'Iwd. prac tically fulfilled all the requircments cssential to the demonstmtion of the life cycle of a heteroxenous nematode. The transmission of swine lunbrworms by earthworms was lateJ· confirmed by the present writers (13), who obserYCd two molt;; in the course of the development of the larvae in the intermediate host. Though the writers' results with reference to the lHunbel' of molts were subsequently questioned by Von Schuckmann and Zunker (113), who confirmed the work of the Hobmaiers, a brief puper 'wllich embodied the results of the writers' investigations (14) on this sub ject up to the middle of 1931 established conclusively the facts with regard to the number of molts in the course of development. of the. two ~pecies of lungworms under discussion.
TECHNIC USED IN INVESTIGATION Adult hmgworms were obtained from the bronchioles of lung;.; 01' swine from various 'parts of the country. The worms were ('ur(' fully removed with the aid of forceps, washed in physiologic saline solution, and sorted as to species. When infested With lungwonns, .. swine almost invariably harbor n mixed infestation with jll('tasrron~ .QyUtl8 elongatus and Ohoerostl'ongy7u..~ pudendotecf:!I.wJ, and are rarely infested with M. saltlni. The intensity of infestation with ellch 0'£ the three species was in the order in which these species have been: named. The gravid, intact females were cut into sniall pieces WWl a pair of fine scissors in a. glass dish containil'g a small quantity of wareJ·. The cut-up material usually contained a mixture of thin-shellpd eg~s and larvae which had just emerged fro~l the e!~gs, as well as tluck-shelled embryonaiRd eggs; the latter dId not hatch in -vitro . . This material also 70ntained nonembryOl)at~c1 and incomp.letely e~n. bryonatec1 eggs wInch degenerated qmcldy 111 water and 111 phySlO
• TbeRe Inve~ti~ntorH l'~ferred tn the enrthwnrmij used In thl'lr hlV('slll!ntlouR til' Lllmbrir:1/8 tcrrcstrl8 mtljor and minor. ,'arletil's wblch hnve no 7.ooJoglcuJ Htllndlng. '1
4 TECH~ICAL BULLETIN" 4':;6, 1;. S. DEPT. OF AGItICULTURE logic saline solution. The cut-up material was thoroughly mixed with a small quantity of soil, obtained from a place on which no hogs had been kept for a number of years; in most caS€s the soil was obtained from the back yard of a, dwelling in the southwest section of 'Vashington, D.C .. all area on which no swine had ever been kept so far as could be determined. A number of earthworms 'were then placed in It glass jUl', or other suitable glass container; to which the contaminated soil had been added; the container was covered loosely with a glass dish. After the earthworms had remained in the small quantity of soil for from 1 to 3 days. during which time at least part of the soil passed through th~ aliment~ry canal of, the an,nelids as shown by the pres ence of typIcal casts m the contamers, the earthworms were removed to l1.:nother glass container to which a considerable quantity of uncon taminated soil had been added; the top layer of soil was covered with several layers of moi!)t filter paper, water being added to the ,.,i filter paper from time to time to keep the soil damp. Under these conditions the earthworms bm:l'owed in the soil during the day. much in the same way as they do in nature. During the day some earthworms were usually found between the layers of the filter paper. 'Vhen the em-thworms were kept under these conditions at room temperature they usually remained alive for weeks, although they frequently decreased in size, presumably as the result of starvation. since no food of any kind other than that present in the soil was available to them. In occasional cultures a heavy mortality of earth worms was observed, particularly during the first few days. In such eases the dead earthworms were removed amI examinell for larvae. and the live worms were transferred to new containers with fresl{ soil. 'WIlen deaths occurred transfers were made daily. and this procedure usually enabled the writers to carry along 'cultures of earthworms uninterruptedly for several weeks. The anterior portion of the alimentary canal, including the phar ynx, esophagus, crop, gizzard, and anterior portion of the intestine ot the earthworms, was examined for larvae; in most cases the hearts. the dorsal blood vessel, and occasionally the ,Ventral blood vessel: were also examined for evidence of infestation. For the purpose of determining the morphological status of the larvae, they were re moved from their locations in the intermediate host, with the aid of dissecting needles, and examined microscopically. In feeding experiments with pigs and dogs these animals were force-fed intact earthworms which had been exposed to infestation for a period adequate for the development 'l)f the larvae to tIll' infective stage. The guinea pigs and oiller animals used were force fed the carefully disseded ante:'ior portion of the alimentary canal and adjoining blood vesl'lels, including the hearts of infested earth worms. Earthworms used in feedin~ pxperiments were collected in places to which swine had not had access for a number of years, so £Ill' al'l ,could be determined. Practically all the earthworms used in e)l.l)eri ments were collected at the Burean of Animal Industry Experim~nt Station at Bethesda. 1\ld. Several earthworms from each lot 1Il tended for experiuulntal infection were examined for larvae, th(' result~ were negative in nearly all casel'l. Occasionally imIhT idual LIF£ HISTORY OF LUNGWORl\IS .PARASITIC IN SWINE 5 ea.rt.hworms were found to harbor slight infestations; more than three larvae were seldom found, but such lots were not used in experi ments involving development of the larvae in the intermediate host. All pigs used in transmission experiments were from litters which. had been farrowed and subsequently reared on concrete floors; the pigs were kept under careful supervision so as to preclude extraneous infestations with lungworms. During the course of this investiga tion, as well as of investigations with reference to other t>wine }lara sites; conducted during the past few years by the writers and others in the Zoological Division, no evidence of lungworm infestation was (lver found in any pig reared under conditions described above. Fecal examinations to determine the presence of eggs in the drop pings of infested swine were made by the salt-flotation technic. Post-mortem examinations of mamr:!.alian hosts were made as fol lows: The mesenteric lymph glands were torn apart with the aid of dissecting needles and small portions were examined in succession in press preparations. Portions of the liYf~r and lungs were exam ined in a similar way. '1[hen larvae were Iwt fOUl.·d in these organs, the latter were cut up with a pair of fine scissors and examined with the aid of the Baermann npparatus. 'Vhen larvae were present, they readily came down the stem of the funnel and could easily be collected for study. Field studies on the prevalence amI abundance of earthworms ill hog pastures, in lots, and elsewhere, were made in points in Mary land, Georgia, and to some extent in North Carolina. Earthworms were obtained from fields and other places by digging in the soil. The specimens collected were placed in glass containers with suf ficien~ soil and examined in the laboratory when convenient. PROTOCOLS ON EXPERIMENTAL INFECTIONS OF EARTHWORMS
INFECTIONS WITH METASTRONGYLUS ELONGATUS
EXPERHrEXT I On August 7, 1929, five earthworms, species undetermined, were placed in soil containing eggs and larvae of Meta.stl'ongybl,8 elonga t168. Individual earthworms were dissected to determine degree and ('xtent of infestation, as shown in the. following results: EarthwOl"m 1, August 13. Five first-stage larvae, 525,.. long b~' 20IL wide recovered from hearts, no examinntion Illade of othel' organs. Esopha!,'1ls of j ~'pical larva about 130,.. long; excretory pore about SO,.. and genital llrimor EXPERIMENT 2 On August 26, 1929, several earthworms, species undetermined l were placed in soil containing eggs and larvae of Meta.~trong!l711,8 6 TECHNICAIJ BULLETIN 456, U. S. DEPT. OF AGIUCULTUHE eZon.qat1lS. Dissection of one of these intermediate host::; was made with the following results: Earthworm 6, August 27. Only one Jarya in intcHtinll1 contents; othl'r organs and tisf EXl'ERH!ENT :J 01) August 27~ 1929, several earthworms, species undetermined, were placed in soil infected with lffetaRt1'ong'ljrUS elongatu.s. One earthworm showed the following infestation: ' Earthworm 7, Se!)tember G. ilearts contained numlJer of' lal'Yae with two ~beaths and some IIll'Y!l.e which hllll 1l1re:uly east off first sheath but still retnjnecl second sheath. One lan'a, with two sheaths, discarded first sheath while un On October 13, 1930, It number of earthworms, H elodtwu.s foetid'!.WJ, wen' exposed to infection with M etast1'ongylus elongat1l.s. Post mortem examinn,tions were made of 12 of these with the following l'esnlts: EartnwOl'lllS 8 and 9, October 15, No, 8 contained three first-stage larvae in wall of posterio:' portion of esophagus; a few laryue in blood vessels. No.9 cOlltained 12 larvae in wall of posterior portion of esophagus; no larvue ill hloocl vessels. Larvae recovered from enrthworm I) wel'e 27;;", to 310", long by 15", wide; esophagus 100", to 110", long, J EXPERB1EN'r r. On October 13, 1930, !1 number uf eurthworms, Helod1'illus aaligi ?lOSUS vur. trapezoiiles, were placed in soil containing egp;s and larvae .. LIFE HISTORY OF LUNGWORMS PARASITIC IN SWINE 7 of 111etf.lst1'ongylus eZongatus. Eight rf the earthworms were exam ined at various intervals with the following results: Earthworm 20, October 15. Six first-stage laryae in wall of posterior part of esophagus; no larvae in blood vessels. EJarthworm 21, Oetober 18. lnve larvae ill wnU of esollhugus, 2 being in anterior portion and 3 ill posterior portion. Larvae had following measure ments: Length, 275jJ. to 300jJ.; width, 15jJ.; length of esollhagus, l00jJ. to 110"" Earthworlll 22, october 20, ll'orty-two first-stage larvtle ill wall of posterior portion of esophah'1lS; no InrYile ill blood vessels, Earthworm 23, October 23, Sb. larvae in wall of posterior portion of esopha l~uS; 110ne in blood Tessels, Earthworm 24, October 29, '.rhirty-ftye larvae in wall of posterior portion of csopilagus; of 10 larvap. ex·amined, 4 had 2 sheaths each and 6 had only 1. sheath each, Onc 11l1'\'a in one of first Dair of hearts, Earthworm 25, Novembm' 4, About gO Inrvae in first pair of hearts; several of these appearcd to be uisintegrated, Earthworms 2fi aml 27, NO\'ember 17. No. 26 !!ontained 3 larvae in wall of postcrior part of esophagus; 110, 27 eOlltaine EXl'ERU1ENT 0 On November 21, 1930, several earthworms, Helod1ilus toetidus, ·were placed in soil containing eggs and larvae of Metast1'ongylus elongatws, Examillations of four eltrthwo~'1~1" were made at vari.ous intervals after exposure, with the following results: Earthworm 28, Novembcr 29, About 100 laryac ill wall I I)Osterior portion of esophnglls: no lar\'ae in hlood vessels, Earthworm 29, December 5, 1\1ore thull200 hll'\'aC in posterior portion of: wall of esophagns: In I'\'ae numcrous in all hearts. Most larvae examined were in seeond stage; It few Ilu'vae had two sheaths each. Enrthworm 30, Deccmocl' la, A total of 320 larYlle in hearts and in waU of ef'ophngus, Earthworm 31, Dcccmher 26, About 500 1Ilr"ae in wall of pOI,terior part of <,,,ophUb'1lS; hearts contained numerous lar\'ae; all larvae in third stage. EXl'EIUME;-;T i On April 8, 1931, several earthworms, species undetermined, were placed in soil containing eggs and larvae of Metastrongylus elon gatus, Four earthworms were dissected, with results as follows: Earthworm 32, April 15, Numerous first-stagc ltll'Vllc in wall of posterior part of e;;ollhagns; lIO lur\'l1e in blood vcs"els, Larvae had following measure ments: Length 375jJ. to 4OOjJ.; width, 15",; length of esophagus, 12.5jJ. to 133jJ.; distance of: nen'e ring, exeretorr pore, and genital primordium from anterior ('nd, 70jJ.. 76jJ.. llIHl 260jJ., respectively, Earthworm 33, April II), First-stage larvae rccoverel1 from wall of esopha gus; a few larvae ull(lergoing first molt, Earthworm 34, April 22, Lal'\'ae in sec'ond stage recovered from posteriol: waU of esorihngus, One (If these lnrvae hnd the fOllowing measurements: Length, 6OOjJ.; width, 26,..; len~UI of esophal,'1ls, 180jJ.: (lisl tlnce of nerve ring and excretory pore from anterior end, 76jJ. and 85jJ., respedivel~'; length of tnil, 50jJ., J EXl'EICI1IIENT 8 On August 26, 1931, several earthworms, species undetermined, were exposed to infection with Metasi1'ongyl'W3 elongatus. One earthworm was dissected with the following results: ' Earthworm 36, September 22, Lnn'ne abundam ,'n wall of gizzllrd, som!' in wnll of CI'OP, Illany in wall of inte;;tine but 0111. in region immedintely posterior to crop, lnrge numbers in- hearts. 8 TECHNICAL BULLETIN 4;)6, 'F. S. DEPT. OF AGRICULTURE INFECTIONS WITH CHOEROSTRONGYLUS PUDENDOTECTUS EXPEllIMt:N'l' 1 On August. 22, 1929, one earthworm, RpeeicRuntletermined. was placed in soil containing eggs and larvae of C lwel'o8t1'ollglllu8 pur/ell rlotectu.8. ThiR earthworni was examined with the following result.. : Earthworm 37, scptl'llIher 3. '[\yO InrVHe ill (i1lp hl'HI·t, one of the~l' lHrVHl' bl'ing 3721' long. ~:XPt:ItI:MENT 2 On A.ugust 28, 1929. Reyeptl (>:lrthwonllR. Hpecies undetermined, were placed ill soil containing eggs and larvae of Olwero8tl·o'ng,l/1u.~ pltde'I/(Zotef'f118. One of these ('arthwol'ms was examined with the following results: .~ l!:arthwol'm 38, DecembeJ' 7. C'untllinell lIU1I1PI'OIlS 11l1'VlIe in wall of esopha gus i 1I0ne ill hlood veSsel!;. On Ortober 13, 1930, a nU1llber of earthworllls, Hflodl'llu8 caligi n08U.~ Ynr. tl'apezoides, were placed in soil eontaining eggs and larvae of Oll.Oe1'o8t'l'ongylAuJ pude11ilot('ef1I,~. Five of these earthworms were examined with the following results: Earthworm 39, Octolwr 15. Onl~' one hu-va in posterior portion of esophageal wIIll; none in blood vessels. EarthWorm 4(1, Oct()lI~r 18. Fourteen larvae in wlIIl of posterior portion of esophaJ.,'1ls; none in hlo\)d vessels. Earthworm 41, Octobel' 2l3. Fifteen laryae in wall of posterior lJOrtion of esol)hagus; none in hloOd vessels. Earthworlll 42, November 1. Ahout 65 third-stll/o:e laryae in wall of posterior Ilortioll of esopha!,,'1ls, 4 Illr\'ue in fir:-;t pair of hearts, 2 h. each of second )"air, and 1 ill one of third pair of hearts. Earthwo!'m 43, November 15. Six larvae in fin-:t puir of hearts, 3 ill Olle of sec()nd pair, and 3 in wull of p(Jsterior portion of e) EXP~J!l MI!l.'IT ·1 On October 13, 1930. n 11l1l11bl'r of earthworms, l:lelodl'ilu8 fodiduo~, were exposed to soil containing eggs and larvae of Olwero8tl·ollg.'jl'l18 pudendotectu,s. Seven of these earthworms were examined with the following results: Earthworlll 44, v EXI'ERIJIlEXT u On November 21, 1930, several ealthworms, Helodrilu8 caligino8us vur. f1'upezoide8, were placed in soil containing eggs and larvae of 01wero8tron!!!llu8 pwlendotectws. Four of the earthworms were ex amined with the following results: Eal'thworm 51, Noyemher 21. About 100 first-stage lIu'me in wall of posterior portiull of esophllgus; none ill hearts, Earthworm 52, Decelllber 5. Allout 150 larvae in posterior portion of wall of esollhugu!';; 1 larnl ill dorsal 11100d vessel; a few hu'\'ae undel'going second molt. Earthworm 53, December 13. About 130 larvae in posterior portion of wall or P!-;Ophah'1lS; non(' in blond ,e:o:sels; most lurvae in third stage. Earthworm 54, December 20, About 150 third-stnge larvaH scattered in esol'hugelll \\"u 11 , mostly in Illlstprior portion; numel'UUH 1I11"l"l1e in one henrt and se,er!ll in e!lch of remaining hearts. EXPEltD£EXT G On April 8, 1931, seveJ'Hl earthworms, species undetermined, were placed in soil containing eggs ancllurvlle of 0 hOel'ost1'ongl/lu.~ puden dotect'1l8. Four of the earthworms were examined with results aR follows: Enrthworm G5, April 15, Mnn~' lar,ae In posterior portion of wnlI of esoplln gns; none in heartH; /Ill in first stage, Larvae had follOwing measurements: Length. nbolit 3C.o/t to 385/t; width, 15/t; length of ('!;opha;..,'1ls, 123/t to 130p.: (lIstllnec of ~('nitnl primordium from uuterior' end, 240/t to 27:i/t, Earthworm 5G, April 1f1. Several larYUc in posterior portion of wnIl of ('~()Jlllngus; olle fil'f!t-Rbll!l' 1111'\'11 :l!)O/t 101lg- hr l:i/t Wi(ll'; e::;ophnguH laO/t IOllg: g('llital prilllorllium 210/t from nnterior cnd. Earthworm 57, Apl'i\ 22, Most la I'vne in posterior portion of \Va \I of esophagus: 1111'VIlI' und('rgoing" sellonll molt, l\l(,llsurempnts Ilf! follo\\"s: Length, fiSOp. to G10/t; width, 26/t; Icn~th of (':o:opllagus, 1401' to lOO/t; distnncl' of nerve ring, cxcretorr pore, und gellltnl 11I'imorilium fr(l11l anteriol' ('ntl, 72/t to 7H/t, 70/t to S7/t, lind a20p. to afi5/t, l'pi;pe('t!v('lr; length nf til ii, 45/t to W/t, Enrthworlll 58, April 2G, Many larvne in esophal,.'1ls and h(,lIrts; :tll in thir(\ INFECTIONS WITH METASTRONGYLUS SALl\U On February 21, 1933,1 ('Ilrthwor1l1!'l (6 of which were Helodrilu8 ca/iginG.':lws val'. f'l'ap('zoides and'l L'1l7noricU8 t(,l'l'est1'i8) were placed jn Hoil ('ontaining eggs and larvae of Metm;t1'ongyluB 8a7mi. Later the,\' were dissected to determine the degree of infestation, with re Rnlts arc; follows: Ell rthworm 59, F('iJrllnry 22. A few fil'st-stnge larvae in wall of esophagus; t\\'o Inrvne wel'(' 2751' nml 300/t long by 12/t wide. Earthw()l'm GO, MlII'ch 1. S('v('rnl first-stage larvae iu wan of csophagus; olle Illrvn 380/t long- by 18/t wille. Earthworm (ll, Mardi {I, Severn I larvae in wall of esophagus, unrlergoing fll'st' molt, Thr('e lm'vlle wel'l' 500/t to 525/t long by 2"2/t to W/t wlell'. Eal'thworm 62, Mllrph 8, FoUl' lllrvlle from esollhugeal wnll were undergoing secuna molt; lnrvlle ffiJO/t to 610/t long b~' 26/t to 28p. wille, .Efll'thwonn {l3, MIII"('I1 11, Several third-stage larvne lind larvlle undprgolng 1 INFECTIONS WITH UND.ETERMINED SPECIES On March 8, 1930, several earthworms, Lwmln-iC1J-8 ferrest'l'i.y, were exposed to infection on soil to which eggs and larvae of undeter jr,4aSO-:l1i--:'! 10 TECHNIOAL BULLETIN 456, U. S. DEPT. OF AGRICULTURE mined species of swine ]ungworUls had been added about a week pre viously. One earthworm was examined with the following results: Earthworm 66, March 20. Several infective larvae in hearts nnd in wnll of esophagus adjacent to crop. PROTOCoLs ON NATURAL INFESTATION OF EARTHWORMS WITH LARVAE OF SWINE LUNGWORMS DurinO'the summer of 1929 the senior author made an invest.iga tion on farms in various parts of Maryland to determine the ('xtent of naturnl infestation of earthworms ,vith the larvae of swine lun/! worms. The results were as follows: Farm 1, Of 10 earthworms, Helodrillt.8 caliyi1wsu8 VUI'. /rapezOidc8, from n hog pasture; 6 were negative nnd 4 positive; fl'om ] to 2 lal"Vlle found In indi vidual enrthworms, Farm 2. Of 4 enrthworms, Helo On Octobrl' 29, 102l) each of 6 pigs out of a litter of 8, farrowed October 18, 1929, was fed 10 earthworms which had been previomlly f'xposed to an infection with Met([.8t1·()J~r1,1llU8 elongatus, On Noveni bel' 8, 1929, each of the remaining 2 pigs, nos. '7 and 8, of this Jitter was fed the. esophag'eal portions' of 5 earthworms which had bet'n (-XpORed to n mixt'c1 infection of 1I1etast1'ongylu8 elongatws and (11/.0(' J'08f1'onfTIJ1'l(8 pudendotechtB, 'fhe pip:s were killed wjth the following' results: Pig 1, NOVl'lIl\)('r 2, Only olle larVII ill a mei:lpnt'erl<' lymph glnud of "Illnil ill(ps tine; exact Idelltfty of larvu not detc1'mlned, Pig 2, November 5, Free from lungworm!', Pig a, Novemhel' 22, ContaiIl(\ci 52 spccl,nens of ltfetnMrollfTlIlfUI elOIlUI/(UN 2 1!u'gest fcmales, 2'4 m11l long b~' 2V6JL I\'lele and 25 n1111 long b~' 312JL wiele', res)1ectively, contained f:!eve1'll1 cmbryonated egg!'; In uteri; most of cgg::; ob serYed were in 1110l'ula slllge; 1 femule, 18 mm long and 2'8OJL wide, contained eggs in 11101'ula stuge, No lurvae found in llvel' and lymph glands; lungs l;iIow('d several hemorrhagic arcus nnd Slightly discolored pneumonic areas at tlP9. Pigs 4 nnd 5, l\fnrch 7 and. 10, respectively. Free from IUng'WoI'111S. 12 TECHNIOAL BULLETIN 456, U. S. DEPT. OF AGRICULTURE Pig 6, March 14. Coutained 24 ful1~' grown lungwOl'ms; females cOlltainl'd cmbryonated eggs, ... Pig 7, November 13. Lung~ showed lletechlul hemo1'l'huges; 6 femules uml J JIIale worlll isolated from these heillorrhuges hnd the following meaHu"ements: l\Iale-tength, BOOJL; width, 32JL. Felllules-length, 1,3 to 1.62 mill; "i'\o:lth, 45,., to 53,.,; length of esophagus, 2101' to 21iJL; width of esophagus, 24,., to 26,.,: ~ £1istance of vulva frol11 till of tuil, 57,., to 6OJL; length of tllil, 381' to 41,.,. ~'hl'l'l' • larvue in process of aegenerution found in lymph gl/lnds of pIg; 1 of them , was 6201' long by 301' wide, Pig 8, l\Iurch 14. Contained se\'el'lll adults of Meta,8tronU/llu,~ c/Ol!f/atIl8 anti Ohoer08trollgylU8 IJudcndotectu8. EXPIm.UHlN'I' 2 On January 3, 1930, one pig, farrowed October 18, 1929, was fed earthworms previollsly exposed to an infectioll with JJIetastl'ongyl'us elongatws. The anima! was killed with the following results: Pig' 9, Janulll'Y 8. Lungs contninetl several petechIal helllol'l'hnges; one luryu in each of three hemorrhagic Ul'ellS examined; no lal'vue In IJ'mph glllnds 0[' liveI', Qne lurvl! from lung'S WIIS a fourth-stuge femnle, 75l)1' long br 311' whll' : \'\II\,a Ull' from till of tail. On April 22, 1930, two pigs, farrowed April 14, 1930, were fed 1 pUl'thworms infected with mixed cultures of l1letast?'onrJylu8 elon,qa- A hfS alld Ohoel'o8t1'01~!JJ/lu8 pudendotectu.~. The allimals wcre killell with the, following results: A Pig 10, April 23. No lan'llt' in intestinul contents 01' mesentel'ic lymph glII lI On ~{ay 12, 1930, two pigs, farrowed April 14, 1930, were feel ~ earthworms infpsh·d with J1/et((RtJ'oll..gyhl'~ elonga.tU8. The animals wer'p killed with the following result.,: .~ Pig ]2, May Ii'i, Twenty-serclI IUI'VIIl' in mesenteric lymph g-lllnds adjacent to hll'ge intestine; lurvae ul1l1crgoing third molt; no lurvae found in liver. Larme from 1~'ll1Jlh glllllc1s weI'(' i'i30!L to mU}L long b~' 301' wille; esophugus 140}L 1'0 100}L long; tnil 20}L to 00", long, ',... Pig 13, Mill' 20. SeveI'll I IUl'vue in wllshings of brollC'hi ull(1 bronchioles; all .... 'WOl'llls nppeal'l'd to be in lifth stage, ~Illles-2 to 3.4 nllll long h,l' i'i91' to ml' ,., wide; esophagus 2491' to 280}L long. L~ellllllcs-3.5 to 4.2 mm long by 651' to 78JL wide; eso]lhagns 327}L 100lg; vulva 0\)1' to 701' fl'OIll tip of tul!; hlil 461' to i'ii'ip, ... long. Lungs of this Ilig shOwed sevPl'ul pl'techinl hCIllOl'l'hllgcs, t:XI'EIUMElN'r r. On ,June 9, 1930, one pig, farrowe(l April 14. 1930, was fed eUl'th- ~ worms infested with JJI eta,~trongyl'1.IS elonga.tu8. This pig was killerl ,. with the following 1'('snlts : Pig- 14, JUlie 12. Lungs showell 1Illlny slllull hemorrhages contllining IUr\'lll' ~ nndel'going molt; severnl IUl'vae in H mesenteric lymph gland adjncent to Inl'~l> intpstine; no lal'Vu(' in liv('l'. EXPlmrMElNT II On December 26 and 27, 1930, six pigs, furrowing date unknowli. i'l WHe fed earthworms infested with lungworm larvae; pigs 15, 1G~ '+ 17, and 18 received earthwol'ms infest.ed with Metastr'o-ngylu8 elon ,qat118, 'mel pigs 19 and 20 received earthworms infested with CllOe- .' LIFE HISTORY OF LUNGWORII:IS PARASITIC IN SWINE 13 1'ostrongylu8 pudendotectu.s. Temp~rature readings taken on these pigs daily from December 26, 1930, to January 5, 1931, did not show any marked variation from the normal. Feces collected Murch 9, 1931, on pigs 16 and 18 were mixed with sand, and each sample was placed in It sepltrate jar. Earthworms placed in these jars were killed March 22 Ilnd found to contain lungworm lurvae in various stages of development in the esophageal wull. The pigs were killed on the dates given with the following results: Pig 15, January 30, 1931. Lungs contained 610 IlIluIts of Met.a.l,ltI'OIl(I1III1,~ cT01tgat1t8j no \vOI'ms or lesions noted in liver, Pig 16, March 6, Lungs contained 326 adults of MetIl8IroIlU/llu.~ clolli/a/rts; no lesions or worms noted in liver. Pig. 17, March 6. No lungworms found. Pig. 18, June 25. Lmlgs contained 136 IIdult>l oj' Metllstrolluylus cloir/lllfIlN. Pig 19, July 1. Nc) luugworms found. Pig. 20, July 17. Lungs contained 1 adult femule of ChOCl'08trOllflJliUH }JucZcndotct'tlls. EXPERI)[E1'(T 7 On :May 9, 1931, each of two 3-month-old pigs were fed eight earthworms infested with larvae of Ulwe1'ost?'ongylu8 puilendoteo ttl8. The pigs were killed with the following results: Pig 21, Ma~' 12. Five larvae in the mesenteric lymph glands, 3 being fourth-stage males, 1, a female in process of she(!ding the two skins, and 1 a third-stage lurva. Males--624,u to 680JL long by 32JL to 37JL wide; esophagus 180JL to 190JL long; nerve ring and excretory pore 72JL to 76JL and 87JL to !)lJL. respectiyel~', from anterior enll. Femule-750/L long by 347JL wide; esophagus 200JL long; nerve ring and excretory pore 76JL and 91JL, respectively. frolll anterior end; tail 41JL long. Third-stuge larvu-430JL long by 32JL wide; tail 41JL long. A young fifth-stage female found in a mesenteric lymph gland was I.l60JL long by 321' wide; esophugus 220JL long; nerve l'ing and excretol'y pore 100JL and l06JL, respectively, from Ullterior end; vulva 72JL from posterior end, the ovary extending 197JL from vulva. No hemorrhagic ureas found in lungs of pig. Pig 22, May 14. Lungs showed several petechial helllorrhages; one ~'oung adult male was recovered from one of these areas; bursa of lI1ule apparent, hut rays incompletely formed i WOI'IIl 1.11 mill long by 45JL wide; nerve rh}g and excretory pore 91JL and 121JL. respectively, from anterior end; spicules somewhat slender and about 418JL long. GUINEA PIGS Several guinea pigs weighing between 350 and 375 g were feel in fective lungworm larvae with negative results. Young guinea pigs weighing 250 g or less were infested experimentally with results us follows: EXPERIMENT 1 On December 27, 1932, each of five guinea pjgs was fed a number of infective larvae of )1/etast1'ongyrlt8 elonflahtH isolated from earth worms. Post-mortem results on these animals are as follows: Guinea pig 1, fed 100 larvae, ldlled Januar~' 26, ]933. No worllls recovered; severnI grayish spots on surface of lungs; other organs normal. Guinea pig 2, fed 250 larvae, killed Janunl'y 26. No worms I'ccovered; uJ.l pel' lobe of right lung showed red hepatization with a few scattered lIelllor rhnges i surfuce of liver contained severn I white spots. Guinea pig 3, fed 500 larvae, killcd January 20. Two lIIales and sixteen females of J[cta-strOlluvT-u8 clOnuUltll,Y reCOver(' GUlllea pig 5, fed 1,000 larvae, killed Janual'~' 26. No worms recovered; upper lobes of lungs showed red hepatization; few hemorrllagic areas in ""'4 lower portions of main lobes; other organs normal. EXPEUIMENT !! On .July 28,1932, each of two guinea pigs was fed the esophagi and 11earts of six earthworms previously exposed to infection with tIll' eg~s and larvae of Olwerost1'011.gylus pudendoteatws and Meta.st1'011 g!/lu.s elongrdus. These animals were killed on the dates Rhown, with the foUowing results: Guinea pIg G, killed July 29, exaci'ly 24 hours after feeding of infective lnng worm larvae. Mf'senteric lymph glands of large intestine contained 45 third stage IHrvne. Two of these larvae 5251' and 5501' long by 251' and 261' wide; esopllagus 1751t and 2101' long; genItal primordium 2551' and 2861' from antrrior pnd; tail 301' !iJIlg. Liver routained 1 third-stage lurYn 4401' long by 2GJL wide; esophagus 17f.iJL long; genital primordium 2551' from anterior end; t'lil 1751' long. GTlil1ca pi~ 7. killell July HO, 48 hours after feedini ·of infective larvae. Yielclel'! 56 third-stnge larvae frum meseIi(eric lymph glilllds, especially those neal' ceCUJll; 1 larva from liver; lanae from lymph glaJ;lds wider than those obtained from guinea pig G. Two larvnp eHch 5251' long by 301' wide; esopha· gus 210,u long; genital primordium 2801' from anterior end; tail 301' long. In 1 lnrva genital primordium 351' long, comiiderably larger tllan those in lnrvae ohtaillCtl from guinea pig 6. EXPERIMENT :l On JUly 30. 1932, each of three guinea. pigs was fed the esophagi nnd hearts of three earthworms previously exposed to infection with eggs and larvae ofMetastrongylus elongatus and Oh,oe1'ostrolngyluR pudendotectw8. Post-mortem examinations of these animals showed the following results: . Guinen IliA' 8. killed August 2, apprOximately 72 hours after experimental in festation. Mpsenteric lymph glands yielded 62 larvae; most larvae sUl'l'oundecl hr two shcnths and 1 larva had already cast off both sheaths. Two sheathcd female Iftl'vlIC GOOJL and 07fiJL long b~' 301' wide; esophagus 2001' and 2251' long; Yuh'lI 151' from anus; tail 411' and 451' long. Lal'Yn which had alJ'ead~' cast oft' lwth slwa1hR WHS 700,u long b~' 301' wiele; esophagus 1901' long; vulva 22,u from ~lllUS; tail 451" lcmg. Male larvHe from lymph gland, with two sheaths, l'eadil~' l'ecO'.,mizah1e hy inflated postel'iOl' portion destined to form hursa. Lungs hacl number of peterhille; of 3 f(>male llll'vae recovered from lungs, 2 had two ~heathll each and 1 had alre:1dy east off sheaths. Shenthed Inrvlle 7401' long IlY SOl' wicl?; ef'opha!,'1ls 1901' 101.g; vulva 221' from anUR; tail 451' long. No ]::r\,:1e in blool1 of heart, in spleen, pancreas, or liYer. Guinea pig 9, died AUI,'11st 10. On AUgURt 9 this anilnal showed 1ubored breathing. Rugge:-;tiye of pneumonia. On post-mortem examination 35 young fifth-stage ]ungwOrms recovercd from lUllg:-;; oth(>rs prellent in thelle organs not removl'!1. F;on1(' femalf's recognizable us OhoerostronUlflll8 Plld.('IU1Qtcctl/..~; others. liS males and females of MctMtronU1/11ls clonU(lt1/.s; one of the latter ('ontained two shelled egA's in uteri. Measurements of ~'Ol1ng fifth-stage worms -were as follows; M. clon{lattl.•~: One lllllh'-length, 4.8 mm; "'idth, 981"; width (If eI';Oph81..'11S, 3491'; distance of ner'l"e ring 111111 excretor~· pore from ant('rior ('nll, 1521' aml 22RJL, respef'ti\'ely; length of f.l1iCules. approximately 1.68 mm. Two iemales--..:length, 5.4 and 8.1 mm; witlth, 831' and 981'; length of esophugus. :~80JL and 4021': distance of nerve l'illg' from Ilnterior ('nd, 1441' and 1971'; llis tam'\:' of ;,ulnt from tip of tail, !)]It and J291t: lenA'th of tUil, 6RJL and 831'. 01wcrostl'ol1U}f1118 111Hl.rndot('ct11.8: One femule-length, 4 mill; width, 1001'; Jengt.h of (>sopha/-.'11S, 3191'; distance of nerve ring from ant(>rior end, 1821': llistance of vulva f1'om tip of tail, 1821'. Guinea l)ig 10, died .An/-.'11Rt 9, after 4: 30 p.m.; examined August 10. On An gust 8 showell respirator~' tlifficult~' suggpstive of 1111cumonia; on post-mortem ('xnminntion, lungs presented lIIottled Hl)pearnnce and contail1Nl peteehillc: microscopiC section of lungs showed congestion of blood veRsels in airflars find blooll in sacs; lungworills in ail' sacs. No lurvae in mesenteric lymph ,i LIFE HISTORY OF LUNGWORlVIS PARASITIC IN SWINE 15 glands or liver; 42 lung-worms recovered from lungs; undetermined numher not recovl'red, Femule lungworms well advanced in lievelopment. ovaries heing fail'ly well developed; male worms had well-formed bursa supported by rays, Largest specimens (1 male and 1 femule) had following measurelllenb;: Fe male--Iength, 7 mm i whlth, 93}L; length of esophagus, 436}L; dil'tullce of nel'Vl' ring and excretory pOl'e fl'om anterior enll, !.!OO}L and 280}L, I'espectiyel~·;. length of tail, 78p., l\£ale--Ienl,'i:h, 2,5 mm; width, 621'; lengtb of esophagus, 27;;1': len~tli of sIlicules, 4501', EXPERr:MENT ~ On Augl1~t 10, 1932, ~ach of two guinea pigs was f~d the esopha~i and hearts of three earthworllls preYIously exposed to infection with (!llOer"ost1'Ongyl'lts pude11 d ot ect~lS and 11/1'tastJ'ongyl1tS elon[Jahis , These animals were killed with the following results: Guinen pig 11, killed ~eptemhel' 7, At begillning of experiment sninllll wei;.!hed 2 OTHER MAMMALIAN HOSTS On No,~ember 1, 1929, oneenrthworm henyily infested with larnu! of Metastr'ongyZu8 elongatu.y and Ohoel'ostr'ongylus pudendotectu,8 was fed to a white rat. Post-mortem examination of this experi mental host on November 5 resulted in the discovery in one of the mesenteric lymph glands of only 1 larva, It male, with the 2 sheaths of the final molt. In view of the fact that ilfetafstr'ongyhl8 elongatu8 has been re ported on a few occasions as II parusite of man, an experiment was carried out to determine the susceptibility of a primate to an in fection with this lungworm. On 1\1arch 0, 1931, a monkt~y, lJfafia~a lasioti13, was fed several hundred infective larvae of M etastl'ongyl!ll!l elong{(tus, obtained from an earthworm dissected the previous day. The m.onkey was killed on March 25 and examined for evidence of lungworm infestation, with negative results. On August 10, 1932, an earthworm which had been infected ex perimentally with swine lungworms and which harbored infeetive larvae was fed to a- cat. Post-mortem examination of this experi mental animal on Spptember 8 fa-iled to diRclose the presence of Iull~rworms. HATCHING OF EGGS AND LONGEVITY OF ARTIFICIALLY HATCHED LARVAE The infective embryonated eggs, obtained from gravid females, were of two types, namely, thin shelled and thick shelled (fig. 1). Thin-shelled eggs are seldom deposited, since observations made by the writers have failed to disclose the presence of thin-shelled eggs in the manure of infested swine. The thin-shelled embryonated egg is one in which shell formation is as yet incomplete. 'fhe thickening of the shell is accompanied by a contraction, and this produces an uneven, some what mammillated surface which bears a resem hlance to the mammillated aHJUminollS laver of A 8cari,s eggs. ~ The supposition made by some investigators, A that hatching of the eg:,r may occur regularly while it is on its way out of the host animaL was not confirmed in the course of this investigat.ion. Examinations of sC/'apings from the tracheae and bronchi of infestc.>d swine .failed to reveal larvae, but llear)y always showed the presence of thick-shelled eggs. Furthermore, in the numer ous examinations of swil1l' manure by the wrHers lflGURE 1.-_-t, T hill ..he\led '!gg of JIeta· with the aid of the Baermnl1n apparntus and in xtroflfl/l/US C/Ollfill/IIS, D. thlck-Rhell~d egg other ways, lungworm hll"Vne were found in only (.If M. c/ongatUo!!. two instances, and in 'Yery small numbers. On the other hand, examination of manure froll1 in fested swine by the salt flotation technic revealed the characteristic lungworm eggs with thick shells, un obser'vation first made by the junior lIuthor, und Intel' ('onfirmed by the senior author. . Under normal conditions the eggs of lun~rworIl1s parasitic in swine are eliminated with the feces of the infested animals and do .not LIFE HISTORY OF LUNGWOR~IS PARASITIC IN SWINB 17 hatch ordinarily until they are taken into the bodies of susceptible earthworms, while the latter are feeding on swine manure or on soil and debris contaminated with such manure. EA-perimentally, earth worms become readily infested with the larvae whic11 issue from the as yet incompletely formed (thin-shelled) eggs. These larvae, as noted by the Hobmaiers (5), the writers. and various other investi gators, are long-lived in water, and, as observed by the writers, appear to be unaffected by putrefactive changes which might take place in this --x."\-f. medium. As noted by the senior author, ''=••,...... ~ the artificially hatched larvae (fig. 2) \ ·"'5' usually beconle quiescent in wuter und, .I: • -----... ~: after a few days' maintenance in that me ~.50,.. () clium. they show little sign of activity un ~ less stimulated by heat~ mechanical pres 50,1.4 sure, or in some other way. Since the behavior of larvae is the same in water and soil, the larvae, therefore, are not adapted to a free-living existence in soil, and hatching under normal conditions is probably accidental. The thick-shelled e SPECIES OF EARTHWORMS IN WHICH SWINE LUNGWORM LARVAE DEVELOPED An undetermined number of species of earthworms were found naturally infested with species of swine lungworms, and several species of earthworms were experimentally infected with the larvae of these parasites. Howeyer, only 4 species of l'arthwOJ'ms iuyolved in tlris investigation were authoritatively detel'll1ined by Frank 76438°-;{5-3 ~~:'~":~'::'l (Y'~.-, - " ;.. 18 TECHNICAL BULLETIN 456, U. S. DEPT. OF AGRIClJLTURE Smith, formerly of the University of Illinois; 3 species were deter mined specifically, and 1 was determined generically only. The specifically determined spedes were (1) Helod1'ilus foetidus (synonyms Alloloboplw1'a foetida and Eisenia foetida), an earth worm of common occurrence in manure, compost heaps, and in soil rich in manure and other decaying matter; (2) H. (ja:ligin lllGRATION OF SWINE LUNGWORMS IN THE INTERMEDIATE HOST The three species of swine lungworms showed no significant differ ence in the rate of their development or in the details of their migra tions in earthworms. The life cycle is treated, therefore, as a unit for ~ the most part. On being ingested by i'mitable earthworms with soil, man1ll'e, or in ) other ways, the eggs hatch and the larvae, once they are free in the lumen of the alim'entary canal of the intermediate Ilost, penetrate its - wall. It is possible that hatching is aided by mechanical pressure of particles of soil against the shells.. Hatching probably takes place very soon after the eggs are taken ]Jl by earthworms, presnmably in ~ the upper p~rt of the alimentary canal; howeyer, this point has' not been deterrmned. When eart.hworms are exposed to soil to which the ,.. artificially hatched larvae 01' thick-shelled eggs Or both have been added, infestation takes place readily, .. LIFE HISTORY OF LUNGWORl\IS PARASITIC IN SWINE 19 The larvae accumulate in the wall of the esophagus of earthworms, especially in that of the posterior portion, and penetrate occasionally the wall of the crop, rarely that of the gizzard, and occasionally that of the intestine. The larvae probably penetrate the wall of the ali mentary canal soon aiter hatching, but whether they penetrate the wall of theef)ophagus or reach their locations in the esophagus by up ward migration from the wall of the intestine, gizzard, or crop has not been determined. Whether the accumulation of larvae in the wall , of the lower portion of the esophagus is governed by chemotactic influences or can be explained in some other way still remains to be determined. It is of interest to note, however, that the wall of the esophagus of earthwoi"ms is well supplied with blood vessels, and, as noted by the writers, the region where lungworm larvae tend to accumulate appears to be highly vascular. On the other hand, it must not be overlooked that, though the wall of the pharynx of . earthworms is also highly vascular, 110 larvae were encountered in this location. The path of migration of the larvae from the wall of the esopha gus, crop, and intestine to the blood vessels has not been definitely traced. It has been observed, howeyer, as shown in the protocols, that the occurrence of larvae in the dorsal blood vessel and their accumulation in the hearts usually take place subsequent to their uccmllulation in the wIIH of the alimentary canal; in the latter loca tion the larvae can and do develop to the infective stage, as shown in figure 3. Hellvy infections with larvae in the wall of the esopha gus, together with the absence of larvae in blood vessels, have been noted in naturally infested earthworms as well as in those experi mentally infected. Migration of lal'Yae from the wall of the intes tines to the blood vessels appears to be an accidental occurrence rat her than an essentittl part of the migrations of the iarvae in the intermediate host. In DllmVl'ic'1l8, the dorsal blood vessel'lies on the alimentary canal, adherent to the intestine in its entire length. except in the region of the hearts; since this blood vessel receives blood from other vessels, the transfer of lungworm larvae from the wall of the intestine to the lumen of the dorsal blood vessel can result either from the migration of larvae in the blood stream or fr0111 their active penetration into that blood vessel. Since the blood in the dorsal yes~1 flows forward, it would naturally carry along, sooner or later, larvae which might enter it. From the dorsal blood vessel the blood enters the ventral vessel through the hearts, and this naturally explains the uccumulation of the larvae in the latter locations (fig. 4). The. lanaI.' are probably arrested in the hearts by the vnlYes and are thus prevented from entering the yentral blood vessel, in which the blood flows ill a backward direc tion. This explains, probably, the rather rare occurrence of larvae in the ventral blood vessel. Figure 5, a dia~rrammatic sIreteh of an experimentally infected earthworm, dis!=iected to show the distribu tion of larvue in various locutions, gives a gl'llphic view of the actua1 findings in the ca!=ie of one experimental infection involving Meta st}·ongylu.s elOllgatWi. The actual l1Umber of larvae found and their loention and distribution are l"l'procluced in this illustration. Yon Schuckmann and Zunker (12) exprl'ssed the view that lung worm larvae do 110t linger in the wall of the alimentary canal but 20 TEOHNICAL BULLETIN 456, U. S. n:rJPT. OF AGRIOULTURE migrate to the blood vess(;'~s almost immediately after penetrating the wall of the esophagus, a view which is out of harmony with the data, presented in this bulletin. Figure 3 shows a very heavy infesta Pl(;l'lU: ::'-l'ol,tlon or the po~tl'rlot: hnlC oC the e~ophll~us of an earthworm (press pT('paratloll) showing IUII,,"\\"OI'III lan'll MOLTING OF LARVAE IN THE INTERMEDIATE HOST Growth and development of the Im'vae, accompanied by two molts, take place in the waH of the intestlne and can take place also in the LIFE HISTORY OF LUNGWOn:\fS PARASITIC IN SWINE 21 blood vessels of the intermediate hOlit. As shown in the protocols and elsewhere in this bulletin, first-sf age larvae, when hatched arti ficially, are less than 400p. long; these larvae attain a length up to 540p. before molting. The two molts occur in rather rapid succession. In. one series of experiments with Metastrongylus elongatus, cnrried out in August, ''';, the first molt was observed as early as the ninth day nfter exposure of l'al'thworms to eggs ancllarvae of this parasite (fig. G, .t1), and the rIGt:ltJ; ·1.-0Uf or the heurts or Ill) (,lll'thwortn wIth 11II1gWOl'III humf'. J(etll8trollfJylu8 CIOIl!luiIl8, iushle. Infection protluced ('XPCl'iIllClltully. X:!25. . sl'co11l1 molt was observed the next. day (fig. (j, IJ). In another series of experiments, carried out in October. larvae obtained from an earthworm 12 days after exposure of the' intermediate llOst to infec tion, had not yet undergone the first molt; llOwever, 3 days later, or 15 days after exposure, one earthworm contained larvae with the loose sheath of the first molt. In another earthworm involved in this expedment, 110 larvae were found in the second molt until the seventeenth day after it had been expos('cl to infection. In another series of experiments, also im'olving iJietastl'ollf}y7u8 eloll 22 TEOHNICAL BUJ..TJETIN 456, U. S. DRPT. OF AGRICULTURE es- ....f--ff I ~ ~ FIOUl::;; G.-A, S .. cflons (If Mcl(/lIlroll (lVll1'" dOnut/tll-ll larva In first. lIlolt: ~ft. nntenor portion: .h right, posterior portion, B, Sec tloll!! of ;If, C/Ollff(/illll Inrvl' ill Second molt: L,'ft, nnterlor por tlon; right, Jlo~t~rlor llortioll, B >---:n7r .....-.nr 1i'IGt'nt} i,-A, f;rl·tlf)n~ of Ohaer,, IItron(/1I/1I1f pluh'/fr/oteoiIl8 larva in tlrst molt: Lt:'ft, nntl'rlOl' portion; "Ight, posh'l'lo(' portion, B, An terior portioll flf O. IJllt/('ndotecttlJ( 1nrvIl in HI'conli 11101 t. FIOUnE 5,-Anterlor portion of nn ('Ill'thworlll showing IO<'I\tlon8 of lungwol'lIl Itll"mf', ,1f('t(//(trOlIf11Nllli r/rJflflrJtllo!/., III wnll of Intestine nnd ~ In c1I'cull,tory 6l'RtClIl: c, Crop; dl.', FIGt:nE S,-Anh'rlol' portion ot In dOrt'l11 blood ve.~HeJ; t'il. (~S gatu,~, carried out in Octob~l', second- and third-stage. larvae were found 12 days after the earthworms had been exposed to infection. In one series of experiments with M etast1'ongylu8 elon[lat-u8, carried out during November and December, secoml- and third-stage lal'vae were found in earthworms 14 clays after these intermediate hosts had been exposed to infection. In an experiment involving Ohoe1'ost?'ongywJ..8 IJudendotectll,s, second-stage larvae still in the first molt WHe encountered 17 day~; after the earthworm hacl been exposed to infection (fig, 7, A). In another experiment with this species, carried out in November and December, third-stage. larvae were encountered 15 days after the earthworms had been exposed to infection (fig. 7, B). In one ex periment with OllOel'osl1'ongylu8 pudendotectu8 carrit'd out in April. third-stage lnnae were found 14 days after the intermediate host. hud been exposed to infection. In one experiment.al infection of €'arthworms with Metast1'ong1jltu; salmi, carried out during the snnune,r of 1933, first-stage larvae ','ere found in the wall of the posterior jDortion of the esophagus about 30 hours after the earthworms had' been exposed to infection; on the thirteenth day after exposure la1'\'ae in the first molt were found in the wall of the esophagus; 2 days Jater larvae with 2 sheaths were found in t.he same location,in another earthwol'm; 18 days after exposure, 1 earthworm contamed larvae enveloped in 1 sheath, that of the second ~nolt, the larvae being located in the wall of the esopha~us and 111 the hearts. It appears, from these data, that the development of swine lung worms in earthworms varies to some extent with the temperature of the sUl'l'ounding medium, developmC'nt being more rapid in warm weather than in cool weather in some cases, and that the second molt commenC'es within a day, or a little later, after the first molt ]las become evident. As with other molting nematode larvae, the separation of the ('uticle from the body is seen, at first, in the head and tuil regions (figs. 6 amI 7). The sheath of the first molt is apparently not cast of[ before thut of the second molt has become separat~d from the body of the larva, these points being clearly brought ont in figures 6B, 7B. Hnd lOB. Larvae "with the sheaths of the molts still adhering to them "were commonly encountered in the course of this study, as shownin the protocols. "However. either during or after the completion of the second molt, the sheath of the fil'flt molt is disC'ardecl, and tIlt' infective third-stage larva is now surrounded by one sheath, that of the second molt (fig: 8). The differentiation or second- lll1d third-stage larvae, when only one sheath is present, is not difficult. since the anterior end of the first sheath is conical, whereas thnt of the second sheath is truncated and characterized by liplike structures. During the process of growth and metamorphosis, accompanied by molting, the larvae continue to increase hi sh'~, those of j1[ eta.~t1·Ollgy- 711)8 elon(fa.tu.~ attainino- It length of 685,.. when inrecth'e, those of ohOCl'08t1'onrly7118 i;';;;&ndotect'u.'I, so fnl' as obser"ed, attaining a length of 625,.. when infective. "AI. salmi, of which only one experi ment.al infection was made, attained a length of 630,,1. as an infective larva. 24 TECHNICATJ BULTJETIN 456, U. S. DEPT. OF AGRICULTURE DESCRIPTIONS OF DEVELOPMENTAL S'fAGES OF LlTNGWORMS IN THE INTERMEDIATE HOST METASTRONGYLUS ELONGATUS EGGS Eggs eliminated with the 1ll11ll11rc of infested swine and in~ested by earthworms are 45,.,. to 57,.,. long by 38,.,. to 41,.,. wide (fi~, 1, B), pllipticlll in shape, thick shelled, and contain an embl'Yo (,'1lC'IORec1 in a vitelline nWll1b rane; the surfnce of the shell is J'olll!henetl, Thin I-!helled embryonated e~gs (fig, 1, A) present in the' uteri are also capable of infecting enrthwornls; these l'ggS are 87,.,. to 100,.,. long by 72,.,. to 91,.,. wide, The shells are very permeable VI wah'r and Rwell considerably in wat{'r cult1ll'es before the ]!lrYae hatch. FIRST'STAGE LAR\'AI!l Artifici~llly hatched first-stage larvae (fi~, !), A) arc fnJIIl 2i;j,.,. to 305,.,. long by 12p. wide. The antel'ior enll is blunt and somewhat nal'l'owed; the posh'rim' end, lllso somewhat lWl'l'myed, is dltlradcl' isticnlly coiled and bent ventrad, Except for nan'owing at the ends, the body of a typical lanta is more or less IInifol'll1 in din meteI'. The esophugus is fi'om 114,.,. to n7,.,. long, with a double swelling; the l'xc:retoI'Y pore p'1St<>rior to filiJ'-;t sW('l1ing is approxi JlJJltl'ly 7;",,.,. from the nnte !'ior pnd, The inteAtine is dark and l!~'nllldHl'in C011 tI'ust to' th(' distinctly li~hI<'r psophnglls; tIlt' l'<>c tumi;:; well llIarkel1 off from the intesthH', The firAt-stnge> larnlC in the wall of l'sophaglls usu ally, and in hearts occa A B !'iol1ally, grow amI attain II. so" h.·ngth of from !lbollt :300IL j;"Gum; Ho-.J, Artillclnlb' hatched lnrvlI of .I{rllt. to Figllre 9. l'howf' k/roll/III/IU, ('/O!/f/(/lllo'( troll' wulet' loU Itu J"(! main. 540p., II lIIirll't] ut: 1000lll j('ml><"l"Illnre, ~howillg morpho. It firRt-stngf' latTa obtain<'d logiclll d.'tllilRo fl, I~it·"t·~tnge IIlIO\,U ot .110 ('/011 !lIt/liM frOlll onl' of fln' Itl'flrts' of Ull 1'II('lhworm 6 from one of tIl('. lll'urts of d:l~'R lifter l'xplJrIIlWn\"/I1 Inff'cliolt, an £'arthWOl'Ill 6 days aft~r {'xPOSlI1'(> of the i'nterm(> In the Aecond stag(' (fig, 10. A) the la1Ta IS surrounded by a sheath which is conical at ,it;:; ant('rior ('11<1, Lan'a, exdusin~ of sheath, is about ;,):,)0/1 to 6i10,.,. long by 2G/~ tn 28,.,. wide, more 01' less trnncllted lit the lI11t{,J'iOl' ('n(t lind attenuated tnward the 110steriOl' end, The esophagus iF; mort' 01,' less club-shfl})('cL 125,.,. to 160,.,. long; LIFE HISTORY OF LUNGWORl\IS PARASITIC IN SWINE 25 with the anterior swelling less distinct than in the first stage. The nerve ring is about 75p.from the anterior end; excretory pore slightly posterior to nel've ring; intestine of more or less uniform width. The genital primordium is about 320p. to 350p. from the an terior end, its location being posterior to the middle of intestir.e, dividing latter into two parts having an approximate ratio of 4 ta 3. The rectum is about 35ft long; the tail, slightly notched, from 35p. to 60p. long. THIRD-STAGE LARVAE The early third-st!t.ge larva (fig. 10, B) has the sheath of the first and seeondlllolts; infectiYe thinl-stage larva (fig. 10, (I) is sur rounded by the sheath of the second lIlolt, tl't1l1cuted at anterior end and showing two characteristic indentations, giving the appearance of lips, Larvae of une series, obtained fro III till enrthwol'\Il about 1 -mI tOO/< r--;(I~ FWURE to,-I,nrvll of J(ctrult/'oll{1JI11I1< l.l()1IUII 111'<: ,l, In first molt: from one of the hClll'ts of 1111 e>u'thwol'm !l duys uftcl' Cxp~~l'lmelltul Infl'ctioll. 11 In second molt: from Oll~' uf thu h.'.'ul'ts "r Ull I'Ul'thwlll'lII tI lluys 111'1.. 1' l'XllPrlllH'lltlli Illf..ct!Ull. 0, In f.",th'e (third Hillge): frOlll (llll' of thl' hl'III'I~ 01' 1111 <'lIrth",,,rm tI dln'~ ufter experi mental Infection, . • month after experimental infe('tion. had the following mensul'l'ments: Length, Gii0ft to 685p.; width. :Wf!: lenl-,rth of dub-shaped esophagus, 150f! to HOp.; diRtance of nl'ITC ring and excretory pore from anterior ('11(1, 7;,p, to H5f! and Raft to 91f!. l't'I'j)l,etively; length of tail, 40p. to 60ft, which tapcrs grndually nnd wnJully POSRt'SSt'R two deep notchc;:, near its end. 111 this series, tlw l'xcretory pore of. the larva led into long excretory glands extendhlg to posterior pOJ'tion of. lar"lI; the genital primordium was postcrior to middle of intestine. The measurelllcnts of another serics 01' infective third-stagc larvae are given in table 1. ']'.\RI••1 1.-l'l'illci/l1/1 1/1('(/811/'('11/('/1111 of }O t1';/'(J,..slagc (illfcdil'e) ltlrvae of ;If cl/l,~1 /'ftll!111111J; clo/lgrl t Il,~ )1en. Length 01 hot.h' __ ._.... _...._•• " .... __ ._..... 625 630 os.~ 625 640 625 685 62.~ {l(l5 ~axlmum WI'j th 01 hody ...... _...... 2~ 60026 211 26 26 20 20 26 20 20 1iO IJiO liO ISO liO liO ISO 170 1,0 Length 01 esophngus••• _... __ ...... _ 170 Distnnoo Irolll excretory pore t(l anlerlor end___ .. _...... " ....._... _...... b:; sa 91 91 91 91 91 88 U1 Dlstnnoo Irom genltnl prImordium to III I Bnleriorend__ . CHOEROSTRONGYLUS PUDENDOTECTUS r IOOGS Thick-shelled eggs are 60p. to 64p. long by 43p. to 45p. wide, similar in shape al,l FIRST'St'AGE TARVAID Artificially hatched lurvae are 325p. to 375p. long by l5p. wide (fig. 11, A.), similar to those of illeta.qtl'ongylus elongatus. The <.'sophagus is 125p. to 130p. long; the net'VO ring slightly posterior to ('ommen cement of last third of esophugus, Growth takes place as D C, ,,'" ~ ...... --,/~:-()~"f---I FlGUlIE l1.-LaJ'va of OilocIYMtroligyl1l8 Plirimld'Jtecflls: .-t, JURt after hntchlng from tbln. shelleu egg; lJ, first stngc, from esopbngenl willi of enrthworm 7 dnYB lifter expert. mcntnl Infection; U, Infeetiv(J (thiL'c! "tug;') Hi dny~ nrtl'1' experlmentnl Infection of earthworm. in il/, f'ion,rla.tU<8, tilt' larvae (fig, J1, /:I) attaining a length of about 525p. at the beginning of the fh'st molt, SECONI)-flTAGE LAIlV.U; The second-stage larvae a1'<.' Rilllilur in measurements to those of MetastJ'ongyltus elonga.tu.~, being 590p. to 630p. long by 26p. to 28p. wide; esophagus 136" to 160p. long; llel've ring and excretory pore 72p. to 76p. and 79p. to 87p., I'cspectively, frol11 anterior end; genital primordium MOp. to 355,.,. frOJil anterioi' end; tail 45p. to 50,.,. long, TllmD'STAG~; LARVAE The third-stage larvae (fig, 11, 0) are similar to those of Meta st1'onglus elongatus. One series of larvae had the following meas urements: Length, 600p. to 625p.; width, 26p.; length of esophugus, 160p. to 190p.; distance of nerve l'ing nnt! excretory pore frolll Ilnteriol' end. 75p. to 82p. and 84p. to 87p., respectively; distance of genital pl'imonlium fmlll antm'ior end, 350/1, to 390p.; ll'ngth of tail, 55p. to 62p., usually with two indistinct not('hes at tht' posterior end, Typi cal variations in morphology of tuil al'e shown in figure 12. An other series of measurements involving 10 Larvae is given in table 2. LIFE HISTOHY OF LUNGWOHMS PARASITIC IN SWINE 27 'f.-I.BLIll 2.-Pri1lCJipaZ lIIcasttrcnumtl! of 10 third'Blaue (infective) larva(, of CllQe/'08tl'Ol1Uylf~ plldondotectl~ :!\>iensurements, in microns, oC larva no. Item 10 1 2 3 4 1 5 I 0 i ------_8L~o Length oCbody•••.•••••••••••••••••• .. , 030 5&~ 610 000 015 505 580 6OO! 5iO 025 Maximum width oCbody...... 20 20 26 26 20 20 26 26 20 26 LengthcC C80phagus...... _. liO 1iO 165 liO 180 155 160 175 160 1U5 Distanoo Crom oxcretory pore to anterior end•••••••••••••_•••••••, •••••••.•-.-. 01 87 85 85 87 91 83 83 80 III Distnnce Cram genital primordium to anterior ond •••••••••••••_...... _••• a05 aa5 a.iO 350 355 315 345 300 Length of tail •••__ • __ • ____ •__ ••___...... 60 55 55 55 flO 55 55 60 a20~li5 02 METASTRONGYLUS SALMI IOOGS The thick-shelled eggs are 43p. t!) 57p. long by 38ft to 41p. wide, l;i11l ilar in shape and general appearHllce to those of the other two species. The thin-shelled eggs lire 72p. to S6p. long by 53p. to 60p. wide. FIIIST·STAGE I,,\IIVAE Only a few artificially hatched first-stage larvae were measured; these were 275p. to 295ft long by 12p. wide. These larvHe are similul' to those of the other two species uncl, like the latter, increase in size as they develop in earthworms. attaining a length of 500p. to 5251'_ and a width of 22ft to 26ft at the beginning of the first molt. At this time the esophagus is from 120ft to 130ft long; nerve ring and excretory pore1 60ft to 70ft and 72p. to 78ft, respectIvely, from a ntf!l'iOl' end; genital primordium, 280ft to 285p. from anterior end; tail, 38p. to 45ft long. SECOND'STAGE LARVAE ],'JGum~ 12.-'flllls of two Infective lnrvue M Th(> second·sta!!e larvae. like OhoerostnmflylUH pUdCIIC/OtCC/U8 ~how· '~'. InJ.; vurlutlolls In Htl'Ucturc: A, '1'ull those of the other two specIes, ~~~II~:t~o~l.dclltntlolls; n, tull with olle differ but slightly from the fully grown first-stage larvae. At the beginning of the second molt the larvae are 550p. to 610ft long by 26ft to 28ft wide; esophagus, 145ft to 160,u. long; nerve ring and excretory pore, 68ft to 72ft and 78ft to 80ft~ respectively, from anrerior end; genital primordium, 290ft to 330ft from ant(lriOl' end; tail, 48p. to 50ft long. THDtP-STAGE r,AltVAE The infective larvae are from 550ft to 630ft long by 26p. wide; esophagus, 150ft to 175p. long; nerve ring and excretory pore, 64ft to 72ft and 72ft to 80ft. respectively, from anterior end; genital pri mordium, 300ft to 3'45ft from anterior end; tail, 40ft to 50ft long, resembling in shape that of OlWCrost1'011.gylus lntdendotectus. 28 TECHNICAL BULLETIN 456, U. S. DEPT. OF AGRICULTURE NATURAL INFESTATIONS OF EARTHWORMS WITH LUNGWORM LARVAE AND DISTRIBUTION OF EARTHWORMS As shown in tIle protocols, individual earthworms, naturally in ,,' fested, have been found to harbor in some instances infestations as heavy as or heavier than those produced as a result of experimental exposure to infective material. Of the naturally infested earth worms which were dissected in th~ course of this investigation, only two species, Helodril!us foetidus and H. caUghw8Us val'. t1Yl.pezoides, were definitely identifi,ed; other species lllay have been involved. As already noted, Von Schuckmalln and Zunker (1~) observed n&t ural infestations in Lurnbrhn.t8 rubell'lls. As in the case of experimentally infected earthworms, the larvat' in natural infestations, as observed by the writers, were present, for the most part, in the wall of the upper portion of the alimentary canal, especially in that of the posterior half of the esophagus; larvae were found in the }learts also in some cases. III a few instanceH larvae were found in a state of disintegration. The assignment of the latter to one of the species of swine lungworllls appears to be justified, however, in view of their location either in the wall of the alimen1;i:. -y canal or in the hearts. It is worth noting in this con nection, that Cod (3) described It nematode from the ventral blood vessel of LWlnln'ieus tm?'est'ris. AccOl'ding to Cori, the larval wormf.; in question were found exclusively in the Yentral blood vessel through out its entire length, a location in which swine lungworm larvae were rarely encountered. Aside from the difference in location, the larvae from the ventral blood vessel of L. tet'J'estris were from 3 to 4 mm long by 1001-' wide, and attenuated at each end; the tail was 1601-' long and terminated in a lmoblike, tip. On the basis of this description, the possibility that these larvae were developmental stages of any of the species of swine lungworms can be definitely excluded. Cori regarded these lalTal worms as being the immature stages of a spirurid, Spiroptem tUJ'di Molin. Another nematode from the ventral blooel vessel of earthworms was describedliy Friedlaender (4) under the name Lumlrri.cicola, VaBOJ'Urn. This form was studied in section only. Whether it repre sents a species distinct from that described by Cori, or whether the two are identicnl, cannot be determined from available information. Other nematodes which occur in earthworms can be readily differ entiated from the larval forms elisclll:'sed in this bul1etin on the basis of morphology and location within the body of the oligochaete host. Incidental observations on the abundance and distribution of earth worms on hog pastures and elsewhere showed that these annelids, at least the two identified species which were found to be naturally infested, were rare or practically absent from fields which had been under frequent cultivation, that thev were not common in fields cov ered with carpet grass or other thiel, grass, and that they were prac tically absent from loose, dry, sandy soils. When earthworms we1'(, encountered in cultivated fields, they were usually found in the lower parts of pastures, especially along the fences. Earthworms were found in abundance 111 uncultivated lots con tRining humus, in pine woods containing It rich and somewhat 100sI,' soil, .in and about manure from various animals, especially that from LIFE HISTOUY OF L1:XGWOlt:lIS PARASITIC IN SWINE .29 horses, cows, and pigs. Although a moist soil was found to be a favorite location for earthworms: a very wet or marshy soil appeared to be a rather unfavorable habit.at for these annelids. MIGRATION OF METASTRONGYLUS ELONGATUS AND CHOERO STRONGYLUS PUDENDOTECTUS IN THE DEFINITIVE HOST In view of the comparati,'e scarcity of 1lletasf1'ongylus salm;i, in swine, this species was not involved in experiments on the migration 01' development of lungworm::; in mammalian hosts. .-\.s noted in con nection with the development and migration of lungworms in the intermediate host, no differences we1'e detected in these respects in the species M. elongatus and Choe}'ost1'ongylu8 pu MOLTING OF LARVAE IN THE DEFINITIVE HOST In guinea pigs as well as in pigs the two final molts take place in rapid succession. In guinea pigs killed 24 and 48 hours, respec tively, after experimental infection, only third-stage larvae, ad vanced in development beyond that of the infective stage encountered in earthworms, were found. In guinea pigs killed 72 hours after experimental infection, larvae with two sheaths, those of the third :md fourth molts, as well as larvae which had already discarded these sheaths, were discovered in the lymph glands and in the lungs. This shows that the fourth molt may take place in guinea pigs be fore the sheath of the third molt has been discarded. It shows -fur ther that larvae arrested in the mesenteric lymph glands of these animals undergo the Just two molts in these locations. Probably the shedding of the two sheaths which. no doubt. hinder to some extent the movements of the lar,ae. enable the latter to ('xtricate themselves -from the lymph g-lands Imd reach their pl't.'fel.Tecl 10catioll in the lungs. As shown in the protocols~ experimental infections of pigs with 111eta.'strongylus elongatus and Olwero8trongylu:s puilendoteetus, re spectively. yielded results similar to those obtained in guinea pigs. The larvae underwent 2 mo1ts, which took place in the lymph glands or in the lungs. Third-stage lar,ae. advanced in development be·, yond that of the infectiye stage, larvae in the thin1 molt and those in the fourth molt with tbe sheaths of the final 2 molts still present, were encountered in pigs 3 days after experimental infection. These findings, as already noted elsewhel'e in this bulletin. are not in har monv with the observations of the Hobmaiers and 'of Von Schuck mann lmd Zunker. who noted onlv 2 molts in the course of the de yelopment of luniworms~ 1 molt" in the intermediate host and the 1 other in the definitive host. According to their observations, lung • worms pass through 3 stages and 2 mo1ts. whereas the data presented in this bulletin show that swine lung-worms. in common with other nematodes, pass through 5 stages and undergo 4 molts. The development of lungwonl1s after the two final molts involves further growth and differentiation. Although pigs killed and ex :unined 3 days after experimental infection containec1molting larvae for the most purt, pi~s killed 1 or :2 (lays later contained larvae which had already ruscarCied their sheaths and were in the .fifth stage. Molting larvae were usually less than 700,u. long; 4-day-old worllli> in the fifth stage were from 750,u. to somewhat over a millimeter long; 8-day-old worms were froll1 2 to 4.2 nun long, the smaller worms being males. A female of M eta8f1'ol1[!ylu~ elongatus contained what app('ared to be fnlly embl'Y0l1atNl eggs 24 days after experimental infection of a pig. Although these worms were not fully grown, LIFE HISTOHY OF LPNGWQIOIS ]'AHASlTIC IN SWINtJ 31 the presence of embryonated eggs in the uteri showed that the worms hlld already attained fertile maturity. The Hobmaiers (5) observed the presence of fully embryonated eggs in swine lungworms 30 days after experimental infection of pi&rs and before the female worms ]111(1 attained full growth. .DESCRIPTIONS OF EARLY DEVELOPMENTAL STAGES OF LUNG WORMS IN THE DEFINITIVE HOST METASTRONGYLUS ELONGATUS Fourth-stage larvae ('an not be di fferentiated easily on l11orpholog ieal ~r()lmds :(rom young fifth-stage worms, SOllie lan'ae recovered from the mesenteric lymph ~lnnds of pigs 3 days after infection were undergoing the third molt (fig. 13) and were, therefore, early fOl1l,th-sta~e lar\'lle. These lal'\'ae had tIll' foUowin~ morphological features: Body l'e}atiYely st,out, 530p. to m5p. long by 30lL wIde; anterlOr end broadly l'ollnded,pos terior end ruther attenuated and tel'lninnt ing in a klJobEke proc'ess; esophagus club sha ped, HOp. to lOOp. long; lH'l'Yl' ring and -excretory pore 65p. and lOp.: re.spectiYely, from anterior end i tai120p. to 50p. long. tlU' short-tailed forms probably being male>=. Sex differentiation becomes more evident, howen'r. in older foul'th-stage. lan-ae. The older male larvae of this stage havl' distended tails,indicating the. beginning of l(l(l/{ 1'''11(' FlGl'll& I!I.-Lur\·" of Mda the iormation of the bunm; female la ~t/"f)IIUUlllX clotll/ot".. III third possess the primordium of the future vulva, JIIolt. F' I' 0 m ml'selltprk lymph gland of pl~ a dny,.: lind haY(> sll'nder tails, One advanced :Ift ltr PXP4.'rilU('utH I lllfl}CtiOll. fourth-stage female larva l'N'overed from the Jungs of a pig 5 days after experimental infection was lo5p. long by 31p. wide i the primordium of til(' vulya was 51p. from tIll' ])osh'J'ioJ' (Ind. As all'tlacly stated, JarVII<' of JIl'fa.~tJ'ollg!/lll,~ elongatu8, in common with those of c.' llOe~'o8t I·(/Ii.qylu,~ lJtldendotectu8, develop rather rap idly in tIl(' final host, sinee fairly wPll-formed fifth-stage worms were I'(>('overed as early as 8 days after experimental infeetion. A~ de s('ription of these WOI'IllS follows: Mnle-Jenl,.,rth, 2 to 3.4 111m; width, 59p. to 7GP.i body slench'r, slightly tapering 'anteriorly unel of same width for most of the }c'ngth; efiophagus (fig. 14) clllo-shaped, 249p. to 280p. !II lengtI;; bursa (fig. 15) well formed, but its rays not so 'we]] dpfuwd as III fully dewioped worl11. Female-h1ngth, 3.5 to -;L~ lllm; width, (j5p. to 78p.i body slender, slightly tnpering anteriorly (fig, 1G. A) and 1I10l'e so l)Osteriorly (fig. 16, B); esophagus club shaped. 3~7p. ill length i vu Vlt ol){'ning to the outside, 23p. from unal opening und' 69p. to 7(jft from posterior end; tuil digitifol'm, 46p. to 53p. in length. 32 ~'ECHNICAL lmLLETIX 456, -e. S. DEPT. OF AGHlCUL'fURE CHOEROSTRONGYL~S PUDENDOTECTUS In yiew of the fact that in the ]l1rvae studied tl1e fourth molt waR already in evidence before the sheath of the third molt had been discarded, it was practically impossible to separate the fourth from , SQ~ FIGURE H.-Anterior pOl-tlon of yonn~ mule Mcta8trollfllllu8 e/ollflat.,8 from on" of thl' hronchl of II pig 8 dnys lIitt'I' ..xp"rlm~ntnJ infection. ---so;;-- ~ r--:;:;;;; FIGunE ll:i.-Bursn oC mull' MetaR/roll FIal'HE IO.-Portions of female .lIell/ flllluM c!onyu.lu8 rL'CoYerell froID une "troJ/up/lis cloll/II/I,u;; rl'co\'l'rcd from of th., bronchi ot II {llg 8 clllYH Ilft"r one o( till' brunchl of II pig 8 day" CXllerllD"ntlli IntectlOn: A, Bnrsll lifter exper1m~ntlll Infection: A. An ~pr"lld out; n, bur~u ill luternl ,·f!!\\". terill" 1101'\1011; /I, Jlosterlor port\lll\, th8 young fifth stnge 011 morphological grounds. The following description is that of fourth-stage lUITlle at the beginning of the last molt (fig. 17, A), the IIll'Ylle in question being sun:oundcdby two sheaths. Males-length, 624p. to 6~8p.; maximum width; 32p. to 34p.; body slender and of Rllllle width 1'01' IlIORt of len/",rth; anterior' end rounded, posterior portioJl~ destined to forll1 bursll, distended; esopha LIFE HISTOflY OF 1.UNGWOTIi\[S PAIlASITTC IN SWINE 33 ~ FIGt'It..: ]'..-..1.• FOlJrth~S:lng(' mulp lal',·:t of elt,u,,.oHfrOll!/J/luR IIIUl('",/otecluH shuwing ht';.:illnin;.: or fourth mult, II, Femnl" IlIn'lI of U, 111It/clltioteelllH with ijheuth~ oi two f1nul moltH; one RIII',,!h WIIS liiscllrri('.1 whil,' InrYII WIIS untler ohs"n'utlon, Buth larvu/, fI'olll m('~ent('.-Ic lymph glumi or pig :: UIIY" tlfter cXjI,'rlllIentul infl'etioll, gm; club-shaped, 180p. to 190p. in length; nel'n' ring nnu e~~cretory pon' 72p.. to 7up.. and 8ip.. to VIp., reHpective1y,from anterior end; tail distended posteriody and showing several indis ,_..' tinct lines and folds, indicating the future bursal lobes and rays; yas deferens already connected to I'ectum, Female---.:body slender, as in male, and of sanll! width for 1l10Ht of length (fig. 17, B) ; one fourth-stage female with fourth molt in progress, 750p.. ill length alld 3.J-p. ill maximuJIl -width; anterior pOl,timl slightly tapl'ring and pos terior portion somewhat slender alld digitiform; l'sophagus 200p.. in length ami club-shaped; nern~ ring and l'xcretol'~' pore, 7up.. an<1 HIp., l'espec tin'ly, from allterior end; vulva. apparent late in fourth stage but not opening to outside until final larval cuticle has been shl'd ; "uIVlt about 31p.. lmte)'ioJ: to alllll opening', and 72p.. fnHI1 posterior end; gonoduct and ovary at this stage not, clearly FIG1:I..: lS,-l'oHtprioJ' 1'1111 uf fourth-stag.' differentiated; tail digitifol'm, 41p.. in len!,rth. f,'mule lun'u of Clloc The posterior portion of a fenlltie with the sheaths j"uxlrlJIIllyluH pllden !loledlls ~h()wlllg be of the two filial molts is shown in figure 18; t~ll' ;.:illllin;.: vf lust mull'. F' r U III IlWHl'U tcrlc sheath of the third molt shows the anal opening' J~'IlI"b ;.:11111<1 of 1\ of the, f(lllJ1:h-stage larva but does not show an pig a dllYH II rter ex ll!'rlmenlllJ ill[pctlon, opening of the reproductive system. ~-IFTH-I:iT_\G~: WORMS The fourth lJIolt evidently j))'o('l'eds !'apidly, sillee yOllng' fifth-stage WOI'I11S have bel'n recoven'd as t·al'ly as 3 days nfter experimental 34 TECHNICAL :BULLETIN 4:56, U. S. DEPT. OF AGlHCULTURE infection. The following descriptions are of a young fifth-stage male J'ecovered from the lungs 5 days after infection (ilg. 19) and of IL typical female: Male-length, 1.11 mm ; width, 45p.; body slendet' and of same width for most of len["rth; anterior end broadly rounded; esophagus club-shaped, 21Op. in length; nerve ring and excretory .pore 91p. and 121p., respectively, from anterior end; !:>picules rathei~ well formed and filiform, abollt 418,u. in length; blll'sa and rays present but latter not yet fully dcveTuped. Female-hody slell(ler, tapering slightly anteriorly and mOre so posteriorly (fig. 20); esophagus club-shaped, 220p. in length; nerve ring and excretory pore lOOp. and 106p., respectively, from anterior end; vulva anterioi· to anal opening, 72p. from posterior end; uterine ducts and oyurips fairly well diiferentiat€d, the latter extending to a distanee of abollt 197p. anteriorly to vlllva: tuil slellder and digitiform, 4;>p. ill len~rth. DEFINITIVE HOSTS OF SWINE LUNG. WORMS OTHER THAN THE PIG 111 investigations on the development of lungworm!:> in the definitive host. feedi ng expel'illlents were conducted not only with pigs, bllt ulso with guine:t pigs, dogs, It white rat, 11 monkey, and a, caL As shown in the protocols in this bulletin, the writers developed experimentully Ale/(I81 1'011 gylu.s ,;lou flatuB and Choe/'08I7'OIlU/I"118 pudendo tectu8 in YOllng guinea pigs to It stage in which the uh'ri of the femall's COil. tail1ed unsegmented eggs; old guinea ~ pigs were l't'fl'Hetory to an infeHtation FWUllt: l!l,-F.:arl~' nrlh'~la;:c 111111(' with these worll1S, Von Lin!';to,,- (If) of C1iIJr.'roHt,.oll(/yluH ,)/IIlt-lIdotcetu8 report€d II Sl)l'cil's of IllIwworll1 from rrom IUlig fI( pig " .1:1)'H II Cll't I'xpcrlml'utll I 111(1'('11011, the brollchi of a dog alld ('~l1ec1 it (,loa cilia ocfodact//{a,. Alieatu (2) noh',l that the description lind figm'l's of O. octodfwt:'jla, were similar to those of ill. eZongahls. and he succeeded in rearing the latter ill two I-month-old dogs as al"l'Sltlt of feeding to these host animals severnl earthworms harboring the infective stage of the lungworm in ques tion. 'l'hedetails of this experin1£'nt IIl'e gin'll in till,' protocoh;. III this cOllnection it is interesting to note that though on(' dog "'a..; killed 32 days after ('xperinH'ntnl infeetion, a 1)l'I'iod udeqnate i'm' the developn1l'nt of the WOI'IllH to pgg-Iaying maturity in pigs, the ft>male worms :from the canine hO!:it cOlltained only nonsl'gmented em,s in the uteri. ""1 white rat fed infective lurvae of Jil'ffl8tr01lgy/u8 dongalil8 and Olwe7'0st1'ol1[Jylus p1.ulendotectu.s yielded only one larvu with the sheaths of the last two molts stiU present, the lurnt bt>ing found in one of the mesenteric lymph glunds. Other larvae possibly present in the lymph glands and elsewhere in the body might have bl'en overlooked in the course of the post-mOl'telll ('xamination of the I'at. An attempt to infect one cat yielr1ptllwgative results as did also an attempt to infect a primate, the monkl'Y J.lfaCflC{[, lm!;otis. LIFE HISTOHY OF LUNGWOll:\IS PARASITIC IN SW:':NE 35 In IHhiition to parasitizing wiltl and domesticated swine, jJfcta st1'OngyZUS elongatus has been reported as a parasite of man in a few instances. Leuckart (8) expressed the opinion that human beings acquired an infestation with these parasites as ll, result of accidentally ingesting an in sect or snail which might harbor the parasite in the infective intenuediate stage. The Hobmaiers (7) found that M. elongatu8 and OlwC1'ost1'ongylus pu d('l1dotectus failed to develop in the horse. These data show that, thollgh lnng worms of swine are not stricthr host !-Jpecific, they do not develo}J in~ othpr hosts to egg-laying maturIty. That dOf;r-3 are likely to become infested with swme lungworms under favorable con ditions may be inferred from the obser yaHons mnde by the senior author that th~se carnivores sometimes ingest earth worms. Man, on the other hand, is not likely to acquire an infestation with swine lungworms, except on 1'are occa sions. Hince an earthworm would seldom be ingested by mall. SYMPTOMS AND LESIONS ASSOCI ATED WITH SWINE-LUNGWORM INFESTATIONS No stl'iking symptoms WNe observed in pigs experimentally infected with lungworms. This can be explained on the ground that the experimel1tal in fections of pigs were light or moderate, apparently insufficient to produce re Hpiratory tlisturbances. The Henior au thor has observed, howe,-er, marked Hymptoms in young pigs which had ac (juired a natural infest.ation with lung worms in a permanent hog lot at the experiment station of the BUI"eau of Animal Industry at BetheHda, 1\lt1. One lJig which eoughed almost continllously was isolated in a pen having II concretn floor lind was observed frol11 day to day. FlGem: 20.-EIll'\Y tifth-Htnj.;~f(,lllnic Aside from conghing, the animal of CIW('/'ost"uIIUylu8 pllllcmlotcct.u8 showed other reSpIratory disturpanees. frum 1lll'Bl'ntcric lymph glnnd of pig :J dnys nfter CXIICl'inll'ntnl ill such as labored breathing, a symptom fectIon. suggestive of pneumonia. Post-mortelll examination of this pig revealed (I, heavy infestation with lung worms, most of whieh, to judge frolll their siZt,. had not yet attaine(l full growth. ~ 36 TECH~ICAL BULLETIX 4(i6, 1:. S. DEPT. OF AGRICULTURE The data given ill th~, protocols with reference to experimental in fections of guinea pigs show that these animals became emaciat~c1 in some instances and showed respirutory difficulty su,!!gestiYe of pneu monia. In one case, the animul sllccUlilbed 10 cluys after experimental infection, and in another, 11 days niter such infection. Alicata (g) noted that 1 of 2 dogs experimentally infected with 1.l/etastJ'ollgJjlu8 tlongatus died from pneumonin on the nineteenth day nfter infection. The second dog began to cough llbout 3 weeks after infection and continued to do so for ubout a week, at the end of whichperiocl the unimal was killed and found to b(' infested with lungworm:;. FlGnm :!l,-Lun;.:~ of n JlI;.: 4 (!nr~ uft"r l'XllI'l"lnwntll1 Infpetion with Jfcfflxf"""ffyI1t8 VI(jIl!J(lIII~. No\!- 1',-h'c!;lnl h('\Il<>l·rllllge~. Enrly lesions associated with lun~wol'ln infestation in pigs, as well as in other experimental animals, are petechial hemorrhages in the lungs (fig. 21), jn whi('h lesions lungworm larvae, with the Rheuths of the two final molts or with these sheaths already cast off, have been found. The hemolThag-es are caused by the penetration of the larvae through the wlllls of the capillaries, blood oozing into the alveoli as the larvae cntt')' the alyeoli and acclllUulate ther€:. The capillaries in the aln~()li IUI\'e been found to be cOllO'ested. Le f::iOllS found in the lungs of guineu pigs ill later stages of (fcvelopment LIFE HISTORY OF Ll:XGWORMS PARASITIC IX SWINE 37 of lungworms were largely consolidations of portions of the lungs, and emphysematous areas adjacent to consolidated areas. This pro duced a mottling on the surface of the lungs. Similar lesions have been noted in experimentally infected dogs also (fig. 22) and in pigs experimentally und nuturally infected with lungworms (fig. 23), the consolidations murkin~ the locations of the parasites (fig. 24), lind being most noticellble III pigs nlong the posterior borders of the lungs. The bronchi and bronchioles of infested ani1l1uls contained pus us well us worms. FIGUUI:l 2!!.-I.ungij of a clog 32 c1I1YS uft"r "xprrlmentll] Infl'ctloll with MetaBtrontlyfllH dOllnatllR. Noto. molt""] IIJlP~ar"IH~l'. Whlt~ nre.. ~ IIr~ "JlIJlhysematou~ ami :lIljaCl!lIt c1nrk"r IITeas lire conS!lliclntccl. Lllngwol'Ills \H're r.~eoVt'red from consoll/latrd portions. 38 TECHNICAl, nULT,ETIN 456, U. S. DEPT. OF AGRICULTUnE i 1,'IGVItE 23.-l o14terlor 1101'1 lOll of Hwlnu lung 24 dllYs aftpr experlmcntlll Infection with Mctastro"(}I!IIIB cl()"flf/III~. Noto emphY$('rillltons IIrellS IIlId udjnccnt consolidlltlol\~ lit tip of Illrgelobe. i' PlocnE 24.-Scctlon of Inng of II dug :12 dllYs tlttel' ('xpcrlmentlll Infection with Mctas. tr""fI1l1IlH el"tlflll'"~: ", ('ullsoildntiun (If Inllg 1111<1 Sl'ctloll of worm III hrollchlole; II. Il'r"IIt1y magnllie.l "ll'W ur ~'j)II~o1i,IIlIl'd portion of lung shown In A. Note section of worm nnd ICUI:ocytps In lJronchlole. LIFJ~ HISl'OHY OF LUNGWOR:\[S PARASITIC IN SWINE 39 SUMMARY AND CONCLUSIONS The three species of lungworms, llfetasi1'on9,1j7u8 eZongatU8, Ohoe 1'o8tl'Ongylus lJudelldoteetus, and ill. salmi, pUl'asitic in swine, are heteroxenous nematodes which undergo the first two stages of their d~velopment in vul'ious species of earthworms. Three species of the oligochaete family Lumbl'icidae, nanlely. Hdod1'ilu8 foeNdus, H. ealigino8us val'. tl'apezoides and Lwmb1'iau8 tCl"resl1'is, one species of the family Megascolecidae, I1l1mely. Diplo cardia. sp., and possibly other species of earthworms, have been shown in the COUl'~e of this investiglltion to sen'c as intermediate hosts for swine lungworms. Earthworms become infested with larvae of swine lungworms as a r~sult of ingesting the eggs eliminllted with the feces of in:festeel Hwine. The eggs lire thick shelled and embryonated when passed in I-iwine feces; they do not hatch until they are ingestea by the inter mediate host. Embryonated eggs obtained from the uteri of gra.vid female lungworms hatch in "itm jf the shell is still thin; the arti ficially hatched lIu'vae, if fully developed, remain ·viable in water for H'veral weeks al1 (6) --. nnd HOIIMAlEB. M. 1929. BIOLOOIE VON CHOt:ROSTltONGn.us (lU:TASTRO:o1GYLUS) PUDENDOTECTUH (BBJo:VIVAGINNrUS) AVS DER LUNGE DJo;S SCHWt:INF.S, ZUGU:XOH EINt: VOltLXUFIUt: ~IlTTt:ILUNG um:R bIE };NTWICKI.UNG DER GRUPPE SYN· THETOCAUJ.US UNSF:nt:R HAUSTIEIIE. l\IUncbell. Tlel'il1·;"tl. Welln· schr. 80: [433J-436, illus. (7) --- und HOllMAIElt, 1\1. 1930. UllElt liAS VEItHALTEN DElt Lt:~GENWUltMElt I't:S SCHWEINt:S, 1In:'1'.\ S'l'UONUYf,US I.ONGEVAOTNATUS UNf) (,'Hm;nOS'l'nONG)'"l.U8 BnEVIV.\ GINATUS, SOWlE VON DICTYOOAUl~US FILARIA DES SOHAFES 1M l'FERIlE, MIT IIEMERKUNGEN zun PATHOLOOISOHEN AN.\TOMIEl Dt:S IIAEMO· 1IIELABlIIA ILgr E'l' .H:JUNI m:fl )!FEum:s. l\Iunehell. Tleriirztl. Wcllllschl'. 81: [361]-3(''"'', illus. (8) LEUCK,\RT, [K G • .Ii'.] H. 1873-76. DIE lInJNSOJU.IOIIEN PARASJTEN UND IlIE VO:o1 IHNEN HElmUlIru:NDEN J,ltANlun:I....:~. 1!.1N lJANII·UNI' U:HRBUCH }'Un NATUnt'OlVJHER UNJ) AEIIZon:. 2 V., lUus. Leipzig und Hei(!elbel'g. (9) LINDEN VON (GnXFIN), ami ZENNJo:CK, L. lU15. UN'n:ltSUCHUNm:N Um:lt IlIE t:N'l'WICKJ,UNU m:n Fnt:I1~t:Bt:Nllt:N m:NEltA· 'l'IONt:N m:lt 1.lrNm:NWUlt~n:n. Centhl. Bukt. [etc.] (1) 76: 147 178, III us. (10) LINBTOW, O. F. n. VON. 1!)()6. NEUE Ht:I.MINTm:N. Centhl. Bald. [pte.] tI) ·n: 749-7ii!!, lIIus. (11) ~IOHLER, J. R. 1920. ltEPOllT OF 'rHE CHmF OF THI': BUltt:AtT OF ANDIM, INJ)US'l'lty. U.K Dept. Agl·. Ann. Hept., fi9 Pil. (12) Ht:HUCKlIIANN, 'V. VON, and ZUNKt:n, l\I. 1930. zuu t:N1'WICKI.UNO nEil SCHWt;Il'rt!·r.I.'NOENWUIt)IEU. Zt:::l'ill'. lufel,· t1on!'!kl'lInk u. Il~·g. HUIIRtiere 3S: 2H3-241l. (IS) SCHWAIITZ, B., 1I1ll1 Ar.ICA'J'A, .1. l'J. 1921). THE D1~n;LOl'Jln:NT m' :ilH;TASTIIONUYLUS ~:LON(lATUS ANIl lIl. 1'UIl;';NUO· '1't:CTI'S IN THt:m INTElIllEUIAn; HOSTS. (AhKtI'Hct) .JOI1l·. 1'111'11' sltol. 16: 100. (14) --- IIm1 AUOATA, J. E. 11)31. CONCEIININll 'rHt: un: HISTOItY (n' I.UNUWOlt)IS IIF SWINt:. .Tollr. PlIl'nsitol. 18: [211-27, iIllls. (]5) Zt:IIltOWSKI, G. lU22. A 1'lIt:I.DIINAIIY nt:I'OUT (.;0; HOO INNIHVOIDIS. Inl1. Aend. fold. PI·nc. 1921 : 205-281, II1l1s. (16)- 11)2;;. s'runu;s IN 1'.lFE HIS'J'OIlY ANII tON'I'IIOl~ OF HUH l.l'NClWUltllS. lml. Acnd. Sci. l'roc. (1924) F/(!o/'ctar}1 of A.I//·ic·1l7tu.}'c______HENRY A. ·WALLACE. Un.cle-/· SeG'reta·I'II ______~ ______. ____ HEXFORll I). TUGWELL. AIJ8istwl/.t. Scm'ctnl'JI ______. ______.1\1. L. WILSON. Di/'cctol' 01' Jj)wtC1/.~ion WOl'k ______C. 'Y~ 'YAltIll'RTON. Director oJ' Pcr801/:neL______.. _ __. 'V. W. STOCIWElIGEU. Direc:tor Of lnfo/'ll/.(lfio/l. ______M. S. EISENHOWElt. Dil'cotol' of Finl/.1to(L______,V. A.•TmIP. 801 ioitol'______SETH ~'HOMAS. ilf/l'iouU'Ul'a.l Adjust'mcnt Aclllli'llilltl'a/iull ____ CHESTIm. C. DAYIS• .f.lamini8trator. /l·II/·ca:lI. Of Agl'i(;u.ltura.lHcono'lllic8 ______NILS A. OLSEN, Chief. B'IIrca·/i. Of A{lrionli:ll1'(1./' HII{liuecrilltl_____ • ___ S. H. lIIcCROIIY, Chief. lI-ul'cau Of Ani/l/a.l. IlIdu8trll______.TOHN R. MOHLElI, Ollicf. Ill/rCll-U. oj Biolo[lioal Sw·vcy______'.T. N. DAHLINll, Chief. /Jllrea'll Of Olle/wistrll a.nd, Suil.~ ______H. G. KNIGHT. Ohicf. Otl/·r:e Of Oooperative Jj)wtenllion Worlv ______C. B. SMITH, Ohicf. jJ'urCalt of DaIrl/ I'I/.d1l,~tI·1/ ______O. E. REEIl, 011 ief. Blweau Of Hntrmwlo{l/l (i.1l(l Pla.llt QUlll'alltille_ LEE A. STRONG, Chief. Officc Of ]iJwJ)erilnent Sta.tioltls ______JAMES T. JARDINE, Ohicf. Pood (I'/Id, D'I'ug AcZm.i1vistl'ation ______W.ALTER G. CAMl'I!ELL, Ohief. Purest Serviec ----______FERDINAND A. SILCOX, OlLicf. GI'(lin F1/.t·urc.~ Ad-minlstr(l.tioll _____ ._.. ____ .T. W. T. DUVEL, Chief'. JJurcau Of Home .EJcorwmic8____ .. __ .. _ ..____ LOUISE STANLEY. Chicf. Libra·l'// -----______• ______.. CLARml'!. R. BAitNETT, Librar·ian. fl1trCll'It Of Pla·l/.t bul1t.~try ______. _____ .... FUEDEItICK D. UICHEY, Ohief. UllrctVu, Of Puolio Roc;.(/..~ ______THOMAS H. MACDoNALD, OlL·it'!. 'Weathcr JJu'l'cnu ______WILLIS R. GIIEGG. Ohief. This hulJetin il; 1I l!uutJ'ihutioll 1'1'0111 H II rl'/Iu. of A'lIi'lll(l/ h/lMI.~trll .. ______;TOUN R. !\Ionr. .EIt. Chief. Zoologi('I1/. Divisioll ______l\r. C. HALL, l'riul'ipal ZOO/Ogi8t, Chief. 42 u. S. GOVERNMI:NT PRINTING OFF1CEI'1935 t • .' ..' \ ~.. L.-=-=.~-," . .n;,~----