March, 1964] SUSSMAN I~T AL.-PEHIODIC COLONIAL MUTANT

CI'TLlm, H. C., AND M. C. CUTLlm. 1!l4S. Studies on KICKEHSON, N. H. 1954. Morphological analysis of the the structure of the maize plant. Ann. Missouri Bot. maize ear. Amer. Jour. Bot. 41: i\7-92. Gard. 35: 301-316. ---, AXD T. X. EMBLER. 19GO. Studies involving Cl'TTlm, E. I!liiG. The experimental induetiun of buds sustained treatment of maize with gibberellic acid. from louf primordia in Druopteri« arislata Druce. I. Further notes on responses of races. Ann. Missouri AIlIl. Bot., n. s., 20: 14:{-l()5. Bot. (;ard. 47: 227-242. (;ALINAT, W. C. I!lGl. Corn's evolution and its signifi­ R~;t;VES, It G. 194G. Methods for studying the maize caucc for breeding. Eeon. Bot. ];i: :{20-;{2;i. ear. Bot. Gaz. 107: 425. (;J<;R:'olERT, B. 1912. A new subspecies of Zea mays Linn. 19:;0. Morphology of the oar and tassel of Amor. Nat. 4G: GIG-G22. muizo. Am«r. Jour. Bot. :37: G!l7-704. HADOHX, K 19G2. Fractionating the fruit fly. Sci. Amor. STI"I:'ol, O. L., AND n. lVI. STEI·'I·'ENSlc:'ol. isso. The ac­ 20G: 100-110. tivity of x-raycd apical moristcms: a genetic and HESLOI'-HARRISO:'ol, J. I!lGI. The experimental control morphogenetic analysis in Zea IIlaYS. Zeitseh. Vorcr­ bungslehre 90: 4S:3-502. of sexuality and inflorosr-once structure in Zea mays L. SFSSI';X, I. I!lG2. Plant morphogenesis, This is life, Proe. Linn. SOl'. Lond. 192: IOS-12:{. J essays in modern hiolorv. Holt, Rinehart and Win­ [\:E~II'TOX, J. H. 1!l21. Inheritance of ramose inflores­ ston, X('w York. ('en('e in maize. U. S. Dept, Agrie. Bull. 971. \VARDLA W, C. W. 1952. Phvlozcny and morphogenesis. EIESSE;LBACH, T. A. 194!l. The structure and reproduc­ Macmillan & Co., Ltd., London. tion of corn. Univ. Nebraska ColI. Agric, Bull. l Gl, 1!l:;!l. Mothorls in plant morphogenesis. Jour, JAI:BENGAYlm, R. A. 1!l49. The vascular anatomy of Linn. Soc. Lond. 5G: 154-159. the eight-rowed ear and tassel of Golden Bantam 1960. The inocption of shoot organization. Sweet corn. Amer. Jour. Bot. :3G: 2:lG-244. ~ Phytomorphology 10: 107-110. i\[ANGELSDOIlF, P. C. 194:;. The origin and nature of WEATHERWAX, P. 1!l17. The development of the spike­ the ear of maize. Bot. Mus. Leafl., Harvard Univ. 12: let of z-« nuujs. Bull. Torrey Bot. Club 44: 4S:{-4!lG. :3:l-SS. I!l:3,i. The phylogeny of Zea mays. Amer. XELSOX, O. K, AND S. N. POSTLETHWAIT. 1!l;i4. Varia­ Midland Nat. Hi: 1-71.. tion in atypical growth in a maize mutant. Amer. WICTMORI';, R. H. 19,i!l. Morphogenesis in plants-a new .Jour. Bot. 41: 739-74S. approach. Amer. Sci. 47: 32G-340.

Amer, Jour. Bot. 51(3): 243-252. ]\)G4. l\10RPHOLOGY AND GENETICS OF A PERIODIC COLONIAL MUTANT OF NEUROSPORA CRASSA1

ALFRED S. SUSSMAN, ROBERT J. LOWRY, AND THOMAS DURKEE Department of Botany, University of Michigan, Ann Arbor, Michigan

ABSTRACT

A mutant of strain (j()-I 113a of N curospora crassa, which shows periodic growth upon bot.h complete and minimal media, was named "clock," and some of the morphological and genetic differences between this mutant and the "patch" and "wild" strains were investigated. In contrast to the uniform growth of "wild," the "clock" mutant produces a series of bands formed hy cyme­ like aggregations of hvphue which become progressively more dense and finally mark the end (front) of a growth hand. A new growth hand is formed by a number of hyphae which grow out as in "wild" strains and dichotomize and form new cymes which again become progressively more dense and finally form a new front. It is shown that "clock" continues its rhythmic growth when cultured in continuous darkness. Sorne "wild" strains were induced to grow periodically on appropriate media. A medium containing equal quantities of sorbose and sucrose caused strain G5-811A (a "wild") to produce the "pateh" type growth. Random isolation, as well as ordered isolation, of ascospores following a eross between "wild" and "elock" show a I; 1 segregation indicating that "cloek" differs from "wild" hv a single gene.

HHYTHMIC phenomena in plants are manifested (Bunning, 1958). The more conspicuous of these in a variety of ways and may well be ubiquitous are those displayed by fungi among which "fairy rings" represent the best-known example (Shantz 1 Reeeived for publication May 29, 1963. and Piemeisel, 1917; Ramsbottom, 1923). Other The authors would like to acknowledge the support of instances where fruiting occurs with a definite the Rackham Fund of the University of Michigan and the United States Public Health Service, National Institutes of periodicity include Penicillium sp. (Sagromsky, Health, Grant-in-Aid RG-9887. 1952), Pilobolus sphaerosporus (Bruce, Weight, 244 A:\IER CAN JOUHNAL OF BOTANY [Vol. 51

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11 Fig. I-ll.-Appearallce of various strains of N eurospora crassa ill growth tulws.-Fig. I. Strain G5-8IIA grown on "complete" medium.-Fig. 2. Strain G5-8llA grown on "minimal" medium plus 0.8% sorbose and 0.8% sucrosc.­ Fig. :t Strain 491 (proline-deficient) on Brandt's medium.-Fig. 4. Strain Gii-8IIA grown on Schaeffer's medium.­ Fig. 5. A small "clock" grown on "complete" medium.-Fig. G. A large "clock" on "complete" medium.-Fig. i-II. The strains were all grown on "complete" medium.-Fig. i. "Clock" with consistent cycle sizes.-Fig. 8. "Clock" showing decreasing cycle sizes.-Fig. 9. "Clock" showing increasing cycle sizcs.-Fig. 10. "Clock" showing cycles of varying size ill noconsistent pattern.e-T'ig. 11. An aperiodic variant of "clock." All figures approx, X 1.2. i\Iareh, 1\)(j-l] e;ue;SMAN ET AL.-PEIUODIC COLONIAL MuTANT 245 and Pittendrigh, 1\)(}Q) , the "patch" mutant of inoculation of a thin film of agar on a microscope N eurospora crassa (Brandt, 1953; Pittondrigh et slide which was incubated in a damp chamber. al., 1959; Stadler, 1959), and several additional Before observation, a cover slip was placed over cases cited in the review by Jerebzoff (1961). Dis­ the culture. The underside of the lid of a plastic charge of spores also may be rhythmic in fungi like Petri dish also served as support for a thin film Pilobus sphaerosporus (Schmidle, 1951), Sphaero­ of agar. Water in the bottom kept the culture bolus stellatus (Friederichsen and Engel, 19(0), and from drying. The mycelium was observed through Sordaria jimicola (Ingold, 1958). Moreover, the top of the dish. Finally, a thin layer of agar periodic alteration in the branching patterns of was added to the bottom of a plastic Cooper hyphae has been found to explain zonations in the tissue culture dish (60 X 15 mm) available from growth of Ascobolus immersus (Chevaugeon, Falcon Plastics, Inc. In this case, observation was 1959a) and, recently, even luminescence in made through the top of the dish. Basidiomycetes has been shown to be rhythmic, Dark-field lighting was arranged through the according to Berliner (1961). The wide distribu­ use of a circular fluorescent illuminator. tion of these rhythms in fungi and the diverse HEsuLTe;-Gross morphology of "clock"-In physiological processes affected suggest that they contrast to the "wild" (65-811A) strain which play an important role in these organisms. shows the usual spreading type of mycelium on Therefore, when a variant which formed "minimal" or "complete" medium in growth distinct bands in a regular periodicity appeared in tubes (Fig. 1), "clock" strains show a banded type one of our cultures of N eurospora crassa, we of growth which varies in the size and regularity decided to study it further. Our hope was that the of the bands (Fig. 5-11). Figure 5 illustrates a amenability of this organism to genetic experi­ small "clock," Fig. 6 a large one, and Fig. 7 one mentation and its simple growth requirements of medium size like the original "clock" isolate. would provide an opportunity to explore the Figure 7 also illustrates consistent band width, mechani-m and role of a biological rhythm whereas the strain in Fig. 8 produces smaller through a variety of approaches. bands with age and the strain in Fig. 9 produces The experiments reported here are designed to larger bands with age. The strain in Fig. 10 outline the range of variants that have arisen from produces large and small bands in no regular pat­ this periodic variant. In addition, we have pro­ tern. Figure 11 illustrates an asynchronous strain, vided a detailed description of the branching pat­ the genetics and morphology of which will be terns of "wild" and periodic strains in order that discussed elsewhere. Several colonial, but aperi­ the groundwork be laid for our future research on odic, variants of "clock," like that seen in Fig. 34, the determination of morphology in N eurospora. have also been isolated. These and the other Finally, the genetic difference between "wild" variants discussed above were obtained from and certain periodic variants will be discussed. backcrosses and sectors. 1IATEHIALS AND METHODs-The original The "patch" mutant of Neurospora crassa, "clock" strain of N eurospora was isolated while which displays a circadian rhythm in the forma­ one of us (A.S.) was screening strain 69-1113a (T") tion of conidia, as described by Brandt (1953) and for mutants at the T'(tyrosinasej-Iocus, through by Pittendrigh et ul, (1959), is illustrated in Fig. the usc of Schaeffer's medium. This variant was 3. The "clock" strains reported here do not form picked because it blackened very rapidly on this conidia. medium (Fig. 28) so that it appeared to be a The growth of a "clock" strain across "com­ "super-producer" of tyrosinase. Upon transfer to plete" medium in a Petri dish is illustrated in "complete" medium, periodic growth was ob­ Fig. 12-17 by dark-field lighting and slight magni­ served to occur, and the strain was retained for fication. The first growth cycle is essentially com­ further analysis. pleted in Fig. 12. In Fig. 13, two hours later, Media that were used included "minimal" peripheral growth has stopped and initial hyphae (Vogel, 1%6), "complete" (Ryan, }\)50), the of the next cycle have appeared. After forward crossing medium of Westergaard and Mitchell progression of the colony has stopped, considera­ (19-l7), and Brandt's medium (Brandt, 1\)5:3). In hIe filling in of hyphae still occurs, especially in addition, the modified Schaeffer's medium the first part of the cycle. The initial hyphae of (Schaeffer, 1%3) used was made up as follows: the next cycle grow forward at a greater rate than Vogel's (1\)56) 50X concentrate (low-sulfur), 20 hyphae in the later stages and appeal' similar to ml; L-tyrosine, 0.181 g; yeast extract (Dileo), 5.0 those of "wild" strain (Fig. 14). Fan-like aggrega­ g ; tryptose (Difco), 2.5 g; sucrose, 1.0 g; sorbose, tions of hyphae appear and become progressively 8.0 g; agar, 15.0 g; distilled water to 1,000 ml. more dense, finally forming the end (front) of a Cultures were maintained at 24 C unless other­ growth band (Fig. 15, 16). The growth period wise noted. A container of water was kept in the (time to complete one growth band) in the strain incubators in order to keep the humidity high, used for the above sequence was about 26 hr at but otherwise no attempt was made to regulate 22 C. humidity. Microscopic morphology of "clock" strains­ Microscopic observation of cultures was ac­ Hyphae of "wild" strains of Neurospora crassa complished in several ways. These included the grow monopodially (Fig. 18). The mycelium COIl..,. 24G AMEHICAN JOUHNAL OF BOTANY [Vol. 51

Fig. 12-1 i.-Dark-field study of growth of a "clock" colony.-Fig. 12. Stage of growth about 2 hr before completion of first cycle, Photographed at 3::30 pM.-Fig. 1:3. End of first cycle. Photographed at 5::30 PM.-Fig. 14. Early stage in second cycle. Note dovcloprnont of hyphae around periphery of colony. Photographed at 3: :30AM.-Fig. 15. Later stage in development of second cycle. Note fan-like aggregates of hyphae at periphery of colony. Photographed at i:30 A~I.­ Fig. 16. Stage in colony development when rate of forward progression is being reduced. Photographed at 9: 30 AM.­ Fig. li. Colony about 4 hr before completion of second cycle. Photographed at 3:30 PM of day following start of obser­ vations. Colony grown in "complete" medium at 2ii C. Xl.i. March, 1964] SUSSMAN F.T AL.-PERIODIC COLONIAL MUTANT 247

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18 19 . Fig. IS-19.-Cumpusite photomicrographs of mycelium of "wild" and "clock" strains of Neurospora crassa.-Fig. 18. Colony of strain 69-1113a grown un "complete" medium at 27C fur 12 hr and photographed in sections which were reassembled in this composite illustration. Note the monopodial branching pattern of this "wild" strain. X 1O.-Fig. 19. Colony of "clock" g-rown on "complete" medium and photographed and reassembled as in Fig. 11'. The dense zone of hyphae designated by the arrow at the bottom identifies the end of the first cycle of growth. X25. 248 ,\:'II!'; IU CAN JO UHNAl, OF BOT ANY [Yol. ;) 1

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Fig. 20-:W. Microscopic dovclopmcn t of a cycl« formed by a " dock" strain of Neurospora (:rasw.- F ig. 20. Hyphae originating from th e periphery of the precedin g r ~· r l e . -F i g. 21. Type of hypha found initiating th e developm ent of a new c~ · ele.- F i g . 22. A stage in hyphul formati on following th e form ation of initial hyphae. Note t he te ndency of t he npi -x of th e hypha at the arrow to di r-ho tomizo.r-s-Fig. 2 ; ~. Further development of dichotomizing hyphae.-Fig. 24. App oaranec of hyphae at th e periphery of a colony neal' th e end of a cycle, At thi s tim e th e primary hyphae have sto pped th eir for­ ward progression.-Fig. 25. Colony ncar the end of a cycle. A hypha may he seen initiating th e next eyelo at th e arrow.­ Fig . 26. Fan of hyphae form ed by th e precocious initiation of growth after th e end of a cycle. "Complete" medium was used for 'all cultures which were maintained at 25C . F ig. 20 approx. X 50; Fig . 21-26 approx. X300. xrarch, 19G4] SUSSMAN ET AL.-PEHIODIC COLONIAL :\lUTANT

TABLI'; 1. Ability of Schaeffer's medium to elicit cyclic ('fable 1). A few such colonies (Fig. 4, 30-32) can growth in "wild" strains of Neurospora crassa and N. be compared with the appearance of "wild" on tctraspenua. Cultures were inoculated in Petri dishes agar medium (Fig. 29). A dark pigment formed in which were maintained at 25 C the bands whieh was not generally distributed in the colony or medium; however, when "clock" Strain number Cyclic growth: strains were grown on Schaeffer's medium, intense Present (+) or pigmentation occurred in both colony and me­ absent (-) dium (Fig. 28). It was found that a "minimal" medium containing 0.8% sorbose and 0.1% Neurospora crassa: sucrose also elicited rhythmic growth in "wild" 69-1113a + es-snx strains and it thus appears likely that the sorbose + in Schaeffer's medium is responsible for inducing S9G01A inos + 11:3-15A + the rhythmicity. Less pigment was formed in the sorbose medium probably because fewer phenolic: 91:3 8"A + 5297a (Emerson) + substrate" of tyrosinase arc present than in 4AR + Sc·haeffer's medium. G9-11:)-R-I0 + Xot all "wild" "trains exhibited rhythmic N. tetrasperma: growth 011 Schucff'crs medium (Table 1, Fig. :3:3, :394.:3 :35). Sinr-o these strains grew colonially, the lack + of rhythm could not be ascribed to insensitivity to N. crassa: sorbose as a paramorphie agent. 89601a Comparison of "wild," "clock" and "patch" 8269-GA strains-It was found that strain (j5-811 A 25a ("wild"), grown on a "minimal" medium to which lA 0.8% each of sorbose and sue rose had been added, formed patches of conidiophores in a rhythmic manner (Fig. 2) closely resembling the "patch" sists of main, radial hyphae and smaller primary mutant (Fig. 3) described by Brandt (1953). and secondary branches. Branching begins about Strain (j!)-1113a ("wild") failed to produce 15-20M from the hyphal tip. The mycelium of conidiophores in a consistent way when grown on "dock" strains is strikingly different (Fig. I!)). the above medium. From the dense mass of hyphae marking the end Stadler (1959) suggested that the ability to of the growth band, a new cycle o~'iginates in a .f~w "escape" on sorbose is associated with the "patch" hyphae that branch monopodially and differ mutation; therefore, to further compare "clock" il~itially from those of "wild" only in the larger and "patch," strains of the former were grown on diameter of the primary and secondary branches "minimal" medium containing a ratio of sorbose (Fig. 20, 21). As the cycle progresses, branching to sucrose of 8: 1, at 2 levels, including 0.8 and becomes more dichotomous, the rate of forward 8.0% of sorbose. Clock strains remained colonial progression decreases, and the number of branches with a much-reduced band width (Fig. 27). per"unit length of hypha increases (Fig. 22, 23). Genetics of "clock" strains-Crosses were made A number of primary branches beeomc main between "dock" and "wild" strains on Wester­ hyphae (Fig. 19) and contribute to the fO~'matiOll gaard's medium (Westergaard and Mitchell, of the front (Fig. 24). Several hours before the 1!)47). In random samples of spores (96-309 front stops its forward progression marking the isolates per cross) from 17 different crosses be­ end of a cycle, one 01' more hyphae may grow tween "dock" and "wild" siblings from original beyond the front at any point. These .hyphae m.ay "clock" mutant X "wild," 15 crosses gave segre­ stop growing after an hour or so and form fan~hke gation of "clock" and "wild" in the ratio of 1: 1 aggregates (Fig. 15, 16, 26), or they may continue (P - <0.10 x2 test); segregation in the remaining to grow, forming the initial hyphae of the next 2 crosses deviated significantly from 1: 1 (P ­ cycle (Fig. 25). <0.01). Since segregation in most crosses was 1: 1, Effect of light-Brandt (1!l53) has ~hO\~'n that it is very probable that "clock" represents a zonation in "patch" occurs when germmatlOn and zrowth take place in total darkness. Therefore, ~imilar experiments were performed with "clock" TABU; 2. Analysis of ordered asci from the cross between and it was found that the rhythm was maintained "clock" strains and strain 85-311A during a series of bi-weekly transfers over a period of 4 months. The only exposure to light was at the Cross Type of segregation time of transfer. In strong continuous light, however the rhythm was found to decay. 1st division 2nd division I ndvction of cyclic growth in "wild" strains of N eV1"Ospora-Several "wild" strains were inocu­ RC X S,j-311A 9 13 lated on Petri dishes containing Schaeffer's me­ lGg X 85-311 A 4 1G 15a X 85-311A 8 12 dium and some were found to grow periodically 250 AMERICAN JOUHNAL OF BOTANY [Vol. ;)1

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33 34 Fig. 2i<~5. Appearance of colonies of "dock" and "wild" strains of Neurospora on various mcdia.-Fig. 2i. "Clock" grown on "minimal" medium plus 8% sorbose and 1%sucrose.-Fig. 28. "Clock" grown on Schaeffer's medium.-Fig. 29. Strain 69-113a grown on "complcte"medium.-Fig. 30. Strain 69-113-R-1O grown on Schaeffer's medium.-Fig. :31. N. teirasperma grown on Schaeffer's medium.-Fig. 32. Strain 6i>-811A grown on Schaeffer's medium.-Fig. 33. Strain 1269-6a grown on Schaeffer's medium.e-T'ig. 34. A revertant from "clock" grown on "complete" medium.-Fig. 35. Strain 89601a grown on Schaeffer's medium. All figures approx. X2. March, 1964] SUSSMAN ET AL.-PERIODIC COLONIAL MUTANT 251

mutation at a single locus. This conclusion is (Jerchzoff, 19(1). However, it should he pointed strongly supported by the fad that ordered out that the concentration of the pure sugars ascospore isolation from 62 asci gave the 1: 1 needed to produce the effect was higher than that ratio ('fable 2). of the sugars found in malt extract. Glucose also Drscussrov-c-Tho growth of many filamentous has been shown to induce a persistent growth fungi, like some Basidiomycetes (Butler, 19(1) rhythm in Lcptosphacria miehotii in the dark, and imperfect fungi (Robertson, 1\l58; Pirt and according to Jerebzoff and Lacoste (19(j2). Amino Callow, 1959), is characterized by the extension, acids in a potato extract medium substitutes for at regular intervals, of lateral hyphae which usu­ yeast extract in eliciting zonations in Aspergillus ally form well below the apex. As the fungus ochraceus (Jcrebzoff, 19(j1). That a balance he­ progresses over the medium, there is very little tween the concentration of certain salts and other variation in the density of the mycelium. This nutrients is important in the establishment of pattern of growth is to he contrasted with that of such rhythms has recently been proposed (.Jereh­ the "dock" mutants of Neurospora in which the zoff', 1\l62; Chevaugeon, 1!l5!lh). monopodiul type of growth described above is Physical factors which induce rhythms in the maintained for only a short time at the beginning fungi include light in illonilia [ruciicoia (Sagrom­ of a cycle. Thereafter, the hyphae branch in­ sky, 195B), various species of Penicillium «rcasingly until the growth is almost entirely (Jerebzoff, 19(1), Trichothceium roscurn (Sagrom­ dichotomous, at which time forward progression sky, 195G), Pilo!Jollis sphoerosporus (Schmidle, ceases. As a result, a zone is formed due to the 1%1) and others. By contrast, hath "clock" and relatively sparse mycelium formed at the he­ "patch" will grow periodically even in total dark­ ginning of the growth cycle, followed by the ness, t.hcrchy demonstrating a "free-running" denser mycelium formed during the time of rhythm. dichotomous growth. The regular succession of such zones distinguishes the growth of "dock" Ll'I'EltA'rUHE crncn from that of "wild" strains. Very similar differ­ ences appear to occur hctwccn "wild" strains of BBIlLIC\EIl, 1\1. D. 19li!. Studios in fuugal lumincsccncc. Myr-ologia 5:;: ~-!-()O. Ascobolus l:11/11/('rSIIS and the "wavy" ("vague") mutant which was isolated hy Chevaugeon BRA);!)'!', '.V. H. 19;')3. Zonation in a prolincloss strain of Neurospora. Mvcologin --II): 19--1-:W~. (Hl5Ba). BIWCE, V. G.• F. WBIGHT. AND C.:-l. PITTB~DIlIGH. 19GO. The appearance of mutants in Neurospora Rcscttiug the sporulation rhythm in Pilobolus with which demonstrate periodicity in their growth short light flashes of high intensity. Science 1:-11: ("clock") and conidiation ("patch") raises ques­ i28-7;-I0. tions about the significance of the rhythms to the BUNNING, K 195~. Die physiologischc Uhr. Springer organisms. For example, are such rhythms in­ Verlag, Berlin, Germany. 105 p. duced merely as aberrations associated with BUTLIm, G. M. 19lH. Growth of hyphal branching ultraviolet irradiation'! That this is not the case systems in Coprinus dieseniinotu«, Ann. Bot. 25: is shown hy the fact that untreated "wild" 341-352. strains of N eurospora can he induced to form CHIcVAUGI'ON, J. 1959a. La zonation clu thnllo, phenorn­ "docks" or "patches" in media containing certain ene periodiquc autonome choz I'ASCO/lOlus inunersus, ratios of sorbose to sucrose. Moreover, the simi­ Cornpt. Rellcl. Acad. :-lci. (Paris) 248: 1;-ISI-l:-IS--I. larity in the period of these rhythms suggests that 19:j9b. Influence de quelques substances sur Itt manifestation du rhythme de croissance chez I'Aseobo­ the same underlying rhythm is inherent in many Ius im mersue. Compt. Rend. Acad. Sci, (Paris) 2--19: strains of N eurospora, although its manifestations 1703-170:';. may vary depending upon the morphological and FIlIImImICIISI,);, 1., AC\D H. ENm;L. 19GO. Del' Ab­ physiological processes to which it may be schussrhyt.hmus del' Fruchtkorpor von Sphaerobolu« coupled. Another question that may be asked slelluius (Thode) Pel's. Planta 51): :-113-:-126. concerns the role of such rhythms in the organism, IC\GOLD, C. T. 19;')8. On light-stimulated spore dis­ hut too little is known of it in nature to make such «hnrgo in Sordoria. Ann. Bot. (Lond.), N. s., 22: speculations profitable at this time. Moreover, 129-l:);j. the failure of sorbose to induce rhythms in some J l'R1mZOFF, S. J9G!. Etude de phenomenes pcriodiqucs of the "wild" strains casts doubt on their ubiquity che-z quelques chumpignons. Theses, Univ. de Tou­ in N eurospora. However, the wide distribution of louse. rhythms in fungi (.J crebzoff, 19(1) suggests a J9G2. Importance d'equilibres nutritionnols sur selective advantage. la manifestation du rhythrno endogene de zonations chez Alternaria tenuis auct. Com pt. Rend. Acad, Sci, Chemicals other than sorbose have been found 254: 20G2-20G:-I. to induce rhythms in certain fungi. Thus, a mix­ ---, AND L. Laoosru. 19G2. Existence de deux ture of different sugars, including maltose, glucose, rythmes cndogcnes de zonations chez Leptosphaeria sucrose, fructose and raffinose, was found to repro­ michoiii (Wcst.) Sace. Compt. Rend. Acad. Sci. duce the inductive effect of malt extract upon the (Paris) 2:';4: 1483-1485. growth rhythm in Alternaria tenuis when it PmT, S. J., AND D. S. CALLOW. 1959. Continuous-flow was added to agar containing potato extract culture of the filamentous mould Penicillium chrusoqe- 2:)2 A:\IEHICAN JOURNAL OF BOTANY [Vol. 51

num and the control of its morpholog-y. Nature Nachklingen del' Rhythrnik bci Scleroiinia [ruciicola (Lonu.) 184: :307-inO. (Wint.) Rehm. BioI. Zentralhl. 78: 589-597. l'ITTlcNDRIGH, C. 8., V. G. BRUCg, N. 8. ROSI';NWEW, AND SCHAEFFER, P. 19;)i~. A black mutant of Neurospora M. L. RVBIN. 1959. Growth patterns in Neuro­ crassa . Mode of action of the mutant allele and action spora. Nature (Lond.) 184: IG9-170. of light. Arch. Biochem. Biophys. 47: :359. RAMSHOTTOM, J. 192:~. Handbook of the larger British SCHMIDLE, A. 19;)I. Die Tugosperiodizitslt del' asexuel­ fungi. British Museum, London, EnglarHI. 222 p. len Rcproduktion von Pilobolus sphoerosporus, Arch. HOBgRTSON, N. F. 19!i8. Observations on the effeet of Mikrobiol. Hi: 80-100. water on the hyphal apices of Fusarium oTysponUI/. SHANTZ, H. L., Arm R. L. l'IEMgrSEL. 1917. Fungus Ann. Bot. (Lond.), N. S., 22: 1!i9-17:1. fairy rings in eastern Colorado and their effeet on RYA1\, F. T. 19!i0. Seleeted methods of Neurospora vegetation. Jour. Agric. Ros, 11: 191-246. genetics, p. 51-75. In R. Gerard, [cd.], l\Iethous in STADLER, D. R. 19ii9. Growth patterns in Neurospora. medical reseu.rch , Vol. :t Year Book Publishers, Inc., Genetic control of a cyclic growth pat.torn in Neuro­ Chicago. spora. Nature (Lond.) 184: 170-171. SAGROMSKY, H. 1952. Del' Einflusz des Lrchtos auf die Vorncr., H. J. 19;)6. A convenient growth medium for rhythmischo Konidicnhildung von Penicillium. Flora Neurospora (Modium N). Microbial Gpnet. Bull. 1:~: I :~9: i~OO-:3I:t 42-4:3. 1956. Zur liehtinduzierton Hinghildung bei WrcSTERGAARD, M., A:'\D H. K. l\hTCHELL. 1947. Neuro­ Pilzon (III). BioI. Zentrulbl. 7;): :)s;)-:~97. spora: V. A synthetic medium favoring sexual rr-pro­ 1959. Zur lichtinduziortou Ringbildung (V). duction. Amp!'. Jour. Bot. :34:5n-fin.