RESPIRATORY ORGANS INT ARANE/K. Development and Origin of the Respiratory , Organs in Araneae. By W. F. Pm-cvll, Ph.D.. Bergvliet, Diep River, near Cape Town. With Plates 1—7 and 7 Text-figures. r «» CONTENTS. f ' • PAGE | I. Introduction . .2 •f Material . .3 Biological Observations . .6 r Treatment .... 7 II. General Orientation . .9 Lung-books . .9 I Trachete . .11 III. Historical (Development) . .12 Development of the Lung-books in Araclmida . 12 Development of the Trachea; in Araneae . 16 IV. The Provisional Abdominal Appendages in the Embryo of Attus f loricola . .16 V. The Development of the Lung-books . .17 Stage with two Pulmonary Furrows . 17 Stages with three or more Pulmonary Furrows . 20 Formation of the Spiracle . .22 Sinking of the Appendage . .22 Formation of the Pulmonary Saccules . 23 Comparison with the Gill-books of Limulus . 25 Later Development of the Pulmonary Saccules . 28 The Chitinous Lining of the Pulmonary Saccules . 31 The Moulting of the Lung-books . .32 The Operculum of the Lung-books . .34 The Lung-books of the Young Spider . 35 Critical Remarks on the Literature . 36 The Fully Developed Lung-books of Spiders . 41 VOL. 54, PART 1.—NEW SERIES. 1 L W. P. PUE.CKLT,. PAGE VI. The Development of the Abdominal Longitudinal Muscles and their Tendons . .44 VII. The Entapophyses (Ectodermal Tendons) of the Pul- monary Segment . .47 The Interpulmonary (Epigastric) Told in the Adult of Attns . .49 The Intel-pulmonary Fold in other Spiders . 50 VIII. The Development of the Trachete and the Entapophyses of the Tracheal Segment . .53 The Post-embryonic Development of the Tracheal Plate . .57 Critical Remarks on the Literature . .61 The Attus Type and Similar Types of Trachea; in Other Spiders . .62 The Agelena Type of Trachea; and its Development . 63 The Traclieas in the Dysderidse . .68 The TraclietB in Argyroneta aqtiatica . 70 The Trachea: in the Scytodidae, PalpimanidEe, and Filistatidai . .71 IX. The Entapophyses of the Third and Fourth Abdominal Appendages (the Spinners) . .74 X. General Conclusions . .75 The Origin of the Tendinal or Medial Tracheal Trunks in Araneai . .76 The Origin of the Lateral Tracheal Trunks in Araneas 78 The Origin of the Secondary Tracheal Tubules . 80 The Origin of the Lung-books in Arachnids . 81 The Homologies of the Pulmonary Segments in Arachnids . .85 XI. Historical List of Papers concerning the Lung-books of Arachnids . - . .92 List of Literature . .96 Explanation of the Plates .... 103 I. INTRODUCTION. IT is just one huudred years ago that the first anatomical account of the lung-books of Arachnida was published by Meckel ('09), who, like his immediate successors, looked upon these organs as gills, and it was not uutil 1828 that their pulmonary nature was recognised by Johannes Mfiller (J28a, J28b) and Straus-Durcklieim ('28). The latter was also, I be- ^ RESPIEATORY OKGANS KsT ARANB2E. 3 f lieve, the first to point out (p. 315) that the lung-books could be regarded as a special form of ti-acheaa, a view which was later on elaborated by Leuckart ('48, p. 119 note, and '49) and for a time generally accepted, until the appearance of Ray Lankester's paper,"Liraulus: an Arachnid,"in 1881, opened r up the probability of the branchial origin of these organs. While working at certain points in the embryology of a spider some years ago it occurred to me that a more careful ( and detailed investigation of the development of the lung- . books and tracheae than had hitherto been attempted would probably reveal some points of interest in connection with the origin of these organs, and indeed it soon appeared that two important facts had been entirely overlooked, viz. (1) the appearance of the earliest lung-leaves on the free posterior side of the provisional abdominal ap- pendages quite outside of the pulmonary invagi- nation, and (2) the origin of a considerable part of the tracheae fromectodermal tendons (eutapophyses) and not from lung-books. This latter appeared to me a point of particular interest, as it is the only case, I believe, in which the origin of a trachea from another organ not re- spiratory in nature can be clearly demonstrated. My investigations were carried out in the years 1894 and 1895, in the Zoological Laboratory of the University at Berlin, and my thanks are due to G-eheimrath Prof. F. E. Schulze for the use of his splendidly equipped laboratory. About one third of the text had already been written and most of the figures drawn when I left Berlin in 1895 for South Africa, where various circumstances prevented the completion of the paper for the press until quite recently. Material.—The material for the development was collected in the neighbourhood of Berlin, and consisted of the embryos and young of Sitticus (Attus1) floricola 0. K., of which I had an unlimited supply of all the required stages of de- velopment. Besides these I examined a small number of 1 Tins name lias been recently discarded by E. Simon and Sitticus substituted in its stead. 4 W. F. PURCET.L. embryos and young of A pel en a labyrinthica and of Tegenaria atrica, but the account of the embryology in the following pages applies only to Attus floricola, unless the contrary is expressly stated. The material required for anatomical purposes consisted of adult or snbadult specimens of forty-one species mostly ob- tained in the neighbourhoods of Berlin or Cape Town, a.s stated in the list given below. The specific determination of bhe European specimens (except Tegenaria atrica) were made from Dahl ('83), but the families and genera are in agreement with E. Simon ('Hist. Nat. Araign.,' 2nd ed.). LIST OP THE SFECTKS USED. (The twenty-nine species marked with an asterisk [*] were also examined in sections.) Tetrapneumonous Spiders. Fam. Avicularii dse. Snb-fam. Aviculariinas. *Crypsidromus intermedius, Paraquay. Harpactira atra, Latr., Cape Town. Sub-fam. Ctenizinie. Stasimopus nnispinosus, Pure, Cape Colony. Her mac ha sp., Cape Town. Dipneumonous and Apneumonous (Caponia) Spiders. Fain. Eresidse. Eresus sp., Cape Town. Fam. Sicariidas. *Scytodes testudo, Pure, Cape Town. Fam. Dysderidas. *Dysdera sp., Berlin. *Harpactes Hombergi, Scop., Berlin. *Segestria senoculata, L., Berlin. f RESPIRATORY ORGANS IN ARAXJi/K. 'O Fam. Caponiidas. *Caponia spiralif era, Pure, Cape Colony. Fam. Drassidas. *Drassodes (Di-assus) infuscafcus, Westr., Berlin. D. tessellatus, Pure, Cape Colony. *Melanophora (Prosthesiina) Petiveri, Scop., Berlin. Fam. Palpimanidaa. *Palpimanns sp., Cape Town. Fam. Theridiidte. Lafcrodectus geo inetri cus, C. K., Cape Town. *Tlieridion lineatum, 01., Berlin. Fam. Argiopidas. Sab-fam. Linypliiinas. *Linyphia triangularis, Cl., Berlin. Sub-t'aui. Tetragnathinae. *Pachygnatha Listeri, Sund., Berlin. Snb-fam. Nepliilinas. Nepliilasp., Senegal. Snb-fam. Argiopinffi), Argiope clathrata, C. K., Cape Town. Fam. Thomisidae. *Philodroinus (Artanes) fuscomarginatus, De G., Berlin. *P. (Artanes) pallidus, Walck., Berliu. *Tibellus oblongus, Walck. Fam. Clubionidas. Palystes sp., Cape Town. *Clubiona holoser.icea, De G., Berlin. *Zora sp., Berlin. Fam. Agelenidce. *Argy ronetn aquatica, Cl., Berlin. *Textrix lycosina, Sund., Bei'lin. *Agelena labyrinthica, Cl., Berlin. *Tegenaria atiica, C. K., Berlin. T. domestica, Cl., Cape Town. 6 W. 1\ PUKCELr,. Fam. Pisauridaa. *Pisaura (Ocyale) mirabilis, Cl., Berlin. *Dolomedes sp., Berlin. Fam. Lycosidas. *Lycosa (Trochosa) sp., Berlin. *L. (Pirata) hygrophila, Thor., Bei-lin. *L. (Tarantula) aculeata, CL, Berlin. L. Darlingi, Poc, Cape Town. *L. sp., Berlin. Fam. SalticidtB (Atfcidae). *Sitticus (Attus) floricola, C. K., Berlin. S. (Attus) sp., Berlin. *Marpissa (Marpessa) mucosa, CL, Berlin. Biological observations.—Attus floricola fastens its co- coons on dead branches, etc., on the edges of the lakes in the Grunewald, a forest near Berlin, and I have found as many as twenty or thirty cocoons closely packed together in a group at theN.W. corner of Hundekehle See. The number of eggs in a cocoon varies normally from about thirty-five to fifty, and eggs may be found in the cocoons throughout June, July, and the first half of August. A number laid in captivity on July 12th hatched (i. e. burst the egg-shell) on July 28th and 29th, i. e. after sixteen to seventeen days. At the time of hatching the embryos are still very imperfectly formed and very much resemble Locy's fig\ 10, except that the legs, which are curved inwards and ventrally, are segmented. The pedipalps are each provided at the base with a small conical tooth, which is broader than high and drawn out at its apex into a tiny brown point. Shortly before hatching the egg-shell becomes stretched and raised on the tips of the two teeth, which then split it across in front of the chelicera.1 1 I also found the two teeth in Xysticus, Tegenaria, and Age- ltina, the teeth and the part of the cuticula on which they stand being black in the two latter genera. These teeth do not appear to have been previoiisly observed, and they have been recorded in Korschelt and f RESPIRATORY ORGANS IS ARANE^. 7 After hatching the embryos remain motionless for five to six days or even a little longer before the first post-embryonic moult takes place, after which the young spiders acquire the use of their limbs. They are still, however, in a very im- perfect condition, especially as regards the eyes. They remain in the cocoons until after the second moult, which takes place sixteen to seventeen days after the first. The young spiders then emerge in a perfect condition, with fully-developed eyes, and have also acquired the definite shape of the adult.1 The entire development, therefore, takes from about thirty- seven to forty days, less than half of which number is spent within the egg-shell. Treatment.—The preserving reagent upon which I mostly relied was a hot concentrated alcoholic solution of corrosive sublimate, which I make use of in the following manner : A quantity of sublimate is placed in a small, loosely corked, boiling flask with some alcohol of 70 per cent, and heated over a flame with constant shaking until the alcohol begins to boil.