TUPETEGAD ERLE REE ED Shh TReteA ARAN TEUULRREEEEET ERD ELE A sa HN LAN ill a Ace 42149 j mr ii {ii iN iit a af ni on in :: = | iaatl | fli | | | —————— “SS ——————— hil MH Hill Hill Mt} i a iH Ii Ht | HU aa il UA HAA i Ue, | HT Hitt I. ee ca ws ss Win i cc i 4791): \a7)} = FN S77, SST Sa SAINGING| P= 1\\ _\\ Sy Es/ AIS IN 7 (Witter leale y Dal 1.) : is \\ \ / Ta, in q SiS INZ/INS A) *, Nf) 72a! LUAU a= a bart ‘FS yy >. I fa o¥K p} ——— a ui — : thy a — « om , . 7 wre ’ .. rT > + A al ‘ . st . he 5 ee be a gay ~ = ~ 1 - - 3 7 s - . ~ -. _ - - - | . . --) > ad i CARDEDNOV 16 988 TI, ne Marck. oF soe ee ener — , ae bet s —_ — . ~fx} | a LD 7 Pet é 4 Baas ¢ f Y es Cal te a eee 0G é — COMPARATIVE ANATOMY. B-Y C. TH. v. SIEBOLD ann H. STANNIUS. TRANSLATED FROM THE GERMAN, EDITED WITH NOTES AND ADDITIONS RECENT PROGRESS OF THE SCIENCE, BX WALDO I. BURNETT, M.D. VOLUME .t. BOSTON: Gin Jaa ene iN COL N, 59 WASHINGTON STREET. 1854. Entered according to Act of Congress, in the year 1854, by GOULD & LINCOLN, In the Clerk’s Office of the District Court for the District of Massachusetts. STEREOTYPED BY HOBART & ROBBINS, NEW ENGLAND TYPES AND STEREOTYPE FOUNDERY, BOSTON. PRESS OF G. 0. RAND, CORNAILL, BOST®s 363 oe EI35¢ atnvert, i ANATOMY OF THE PNY ERP b Bea EA. BY G2 THis SEEBOLD: FEB 28 1986 LIBRARIES BOSTON: eOUGLD AND’ LINCOLN, 59 WASHINGTON STREET. 1854. fe Wey 0h) i ie ; CR wt i ear: oy ; ie ac : ne) ane vid Me ; CS aoe. Coe avon * i ; Piaiae: ie Rh os iat Cy “ fo MY ESTEEMED FRIEND, EFOvW ES sAG A S*S°r'a > ? PROFESSOR OF ZOOLOGY, &c., IN Parbard nibersity, WHOSE WELL-KNOWN RELATIONS TO COMPARATIVE ANATOMY REQUIRS NO MENTION HERE, AND WHOSE SPLENDID GENIUS HAS DONE SO MUCH TO AWAKEN, IN THIS COUNTRY ESPECIALLY, A LIVELY INTEREST IN OBJECTS OF NATURAL HISTORY, H Anscribe this Volume, “WITH ADMIRATION AND SINCERE GRATITUDB,. WALDO I. BURNETT. 1* ve Tea t ty iy id eae a ad piers) Rosa tae | es i ; ‘yr i 1 eee SAY Weretess PALA Mey ee enrtrAya) TAYE A de MAGS, UR AKT AEM ts Fe ‘ , ? t= ’ ree OT Sarg Bik Y, BL ae RV yeree yay RO A) ONE OEA L Hen ty Ms MIE TEE SBE On | r gM RT ea ‘ ti bg ae VAtout a Peiee Tr ees | ed e oa TRAE POAT * a eee hy ne’ i : a + Ae ' ' t . 44 ‘a ‘ : 7 i 5 y : | ; oe i ‘iad NOTICE OF THE TRANSLATOR AND EDITOR. In issuing an English translation of the Lehrbuch der ver- gleichenden Anatomie of VON SigBoLp and STANNIUS, any formal account of the work is quite unnecessary. To all Anato- mists it is a treatise already well and favorably known, and it has justly been regarded as the most complete and comprehensive work of its kind now extant in any language. ‘The high position and distinguished reputation of its authors have been fully sustained by this portion of their labors. But there are several features in this work which should be men- tioned, since by them it is favorably distinguished frowt all other treatises of the kind that have preceded it. In the text will jbe found a lucid yet succinct exposition of the anatomical structure of organs, arranged as far as practicable under distinct types. The details on which this typical summary is based, are comprised in notes which are as remarkable for their erudition as for their copiousness; indeed, the utmost care has been taken in the literature of the various subjects treated, and the student will here find the most reliable and at the same time the fullest refer- ence to the bibliography of nearly every subject in Comparative Anatomy. In this way, the work as a whole furnishes a complete dictionary of the science, and will prove invaluable even as a work of suggestion and reference, to those who would pursue any special line of inquiry and research in this department. It may be truly said that the Microscope lies at the foundation of all our best knowledge of anatomy, and especially that of the Inverte- brata. This is the case, not only on account of the small size of most of the animals, but because, as Von Siebold has said in his preface, the anatomy of these lower forms is scarcely reliable unless based upon histological investigations. Vill NOTICE OF THE TRANSLATOR AND EDITOR. Hence, that part of the work treating of the anatomy of the Invertebrata, by Von Siebold, is rich in the results of microscopi- cal researches; and their value in the elucidation of the subject will be readily appreciated. This plan of procedure has not the same urgency with the higher animals, where the character of an organ or part can generally be ascertained from its position, &e. ; and, in the second part of the work, on the Anatomy of the Vertebrata, by Stannius, details of microscopical structure are comparatively little insisted upon. But, within a few years, the histological compo- sition of organs, even though their character and function is well known, has become of great and increasing interest; and details of this kind, as far as they would be understood without the aid of figures, I have sought to add in their regular order and place. As to the notes and additions generally, they stand by themselves with Ep. affixed, and almost invariably refer to some point treated of in the text or notes of the original, and for the most part relate to the correction, confirmation, or extension of some statements there made. These notes were drawn from all the sources accessible to me; but from the many difficulties in the way of the early receipt of foreign works in this country, they are not as complete a record of the recent progress of the science as would be desired. As to the translation, [ may say, that not being a German scholar, but having read the German language chiefly for scientific purposes, I trust that any inelegances of diction or idiom will be excused. But, throughout, I have endeavored to give a faithful rendering of the author’s meaning, and to express this in as simple and terse a form as possible. In conclusion, I wish to express my gratitude to my friends who have kindly aided me in this work ;— prominent among these is Mr. Edvard Capen of this city, who has been of invaluable assistance to me in the labor of passing the sheets of this volume through the press ;— of others. such as Professors Agassiz, Dana, Leidy, and Wyman, their names. will be found honorably recorded by their own important labors in science, to which I have so frequently referred in these volumes. WB. Boston, Nov. 1853. PREFACE. As latterly, Zootomists have given much greater attention to the invertebrate animals than formerly; and as, with these investigations they have united, as much as possible, others upon the generation and development of these animals, such a mass of material, composed, in part, of entirely new and very remarkable facts, has accumulated, that the manuals of Zootomy hitherto published are of a scale quite inadequate to receive them. It is unnecessary, therefore, for me to offer further reason for the task I have undertaken of arranging these materials and reducing them toa systematic form. But the order in which I have disposed them may not meet with general approval, for, hitherto, in works of comparative anatomy, the organs, and not the zoological classes, have served as the basis of the order pursued. But, in the present state of Science, and at least provisionally, it appears to me that the anatomical order should not be followed, for, the types, which, until now, have been recognized in the develop- mental series of the several organs, appear no longer valid and permanent. Indeed, extended researches made upon a great number of animals, have shown that these types, hitherto regarded as express- ive of fundamental laws, may almost be taken as the exceptions. Such genera as Hydra, Lumbricus, Hirudo, Unio, Astacus, &c., can now no longer be regarded as the representatives of certain animal classes or orders, for their organization is far from affording the requisite type of that of allied animals. It appears now clearly determined that the types of the development: and disposition of the various organs of the Invertebrata are more numerous and varied than hitherto supposed, and that, in this respect, a rule wholly differ- ent from that of those of the Vertebrata must here be applied. But as the numberless details which we now possess upon the organization of the Invertebrata, have not been thoroughly worked out and system- atized in all the orders, it is really a task too difficult to here distinguish the rule from the exception, and the type from that which is only a secondary modification. x PREFACE. I have especially devoted myself to the collecting and collating as completely as practicable, the numerous new and important facts in the organization of the invertebrate animals, which have as yet been developed. And as occasion presented, I have verified with my own eyes the particular results; and when I have been obliged to refer to the discoveries and observations of others, I have cited exactly their works. I could not exclude Embryology and Histology from this work, for, in these branches, often lies our only means not only to ascertain the true nature of many larval forms among the lower animals, but also to arrive at the correct interpretation of many organs which, in form, position, and arrangements, have no analogues among the higher animal forms. It is only by the aid of Histology that we are able to show that this or that organ is a branchia, a liver, a kidney, an ovary, or a testicle; while, in the Vertebrata, which are organized after a few principal types, the signification of most of the organs can usually be easily determined by their position and connection. In order to avoid long descriptions, I have, when practicable, re- ferred to plates and figures; but in so doing I have always endeavored to cite the good and original representations, for | am convinced that many figures which are transferred from one book to another, become, at last, so changed as to be quite dissimilar to the original. The elaboration of this work having been commenced in 1845, but its completion having been delayed by my change of residence from Erlangen to Freiburg, and partly by a pretty long sojourn of mine on the Adriatic Sea, I have been unable to use the important works which have been published during the last few years, except in the form of a Supplement [additional notes] which will serve to com- plete, to confirm, or to rectify what has been advanced in the body of the work. I take this opportunity to publicly express my gratitude to A. Kolliker, H. Koch, A. Krohn, C. Vogt, and H. Stannius, for the friendly and important aid they have rendered me in the .completion of this difficult task —not only by the transmission to me of inter- esting and rare marine animals, but also in the communication of important manuscripts and letters, the contents of which they have allowed me to freely use for my work. Frerpure (1n Brursaav), Med. 27, 1848. C. Tu. v. SIEBOLD. TABLE OF CONTENTS. Classification of the Invertebrate Animals,. .....--+.+«s-ee-e Bibliography, Introductory Note to the Infusoria. I. THE INFUSORIA AND RHIZOPODA. Classification and Bibliography, - fee s.25; 3, ape opal eA a 185-187 ay [ies Aya pies elon loAb Cd da dA a oe Se oa. ac 188-190 6. Circulatory System, ...... GhiG PO Mo ats wo A2D—229 XI. THE CEPHALOPHODA. Classification and Bibliography,. ....... ee ear Bie 230 SMM Len ab SIcCLOLOML we” te: fiel ier iRise ve) ls) rey fo. Ye) for Oe 6) 7: Golete hese ere 231-232 2. Cataneous Envelope, ... . 2. 2. 2 es ese Sceiisiesh eianeel (280-200 3. Muscular System, and Organs of Locomotion,. ..... .- - » » - 236-288 PNET VOUS) Sy StCHIsp 6) oc: hush gsi sy oeh ie ish carat tel (w, pipe le piel tel a) ais 239-242 Dy LASSEN) i Gecaiy CREM RCE CCE CLEMO yu. ag aa 243-247 GheIeCStLVe ApPDArHdUsyy « «4 is » © ss cee he, Pilate tlie, Ss bie 248-250 Weeeivculatory, Systems v.06 0s). 6.4» o's eipe: for hi perhete. suave 251-552 SmelespiratorywOrgans, ¢ «5 «6 6 wiles 3 5 is 6 6 see 8 8 00 le 253-254 2 XIV CONTENTS. SECTION O.1Oreans of Secretion, (> sit oe %e-= ‘6% © 2 ©» 0) fonsl oaeieleanO— 20D it, lime Ole IGG oe Solo) co Ooo oO ONO) oO o90.0 a Oo < 255 Il. Organs of Special shoigtaae Sie. teh lee! wy Grae mettre tel Seale manne 256 10. Organs Of Generations, sure. <, vas arvigeet ap cyl x) epee Sh siege 2b i226. Introductory Note to the Crustacea. XI. THE CRUSTACEA. Classification’ and Bibliogmaphiys <<) 1-12 = cells! cl b-' ool Melee atmo) |e 262 1. External Envelope, and Cutaneous Skeleton, ......-.+.--.- 268-266 2. Muscular System, and Organs of Locomotion,. ....... + + . 267-269 3}, INGO SBM 505 6 oO 0 b OO B beu0 deo 0 G80 O)o 040 . . 270-278 A OCEANS OLNSCNSC) (ate Mremommalnelnalte 6) “9! le) HetoeckO: DO GNb- 6 274--277 pamDigestive Apparacuss macmamamiaNte l(a cl teat ol fo) tell ol (aolclliieilin Menlelitcll= 278-281 6. Circulatory System, ..... 0.0) OUD tao. Gag ao our C0. 0-7 282-284 ie Ide OMEM OM FSNEMEEN, oc a ope bb oO oO oO bl 5 Oo ob oo 8 285-287 Sh, Ohmi @i Seogiin, 5 5 5 oo Ooo OOOO do oO . . . 288-289 If, Whatehay Owen) 6 5 54 5 6 8 Bo load Dio Bo oped a Heard 288 Il. Organs of Special Secretions,' ........ Gluintie Evora Pog 289 SOrcams\ of Generations. (it 0 et 8) - + ell Aa ere aes are tod Te 290-294 ie Hermaphrodite (Crm 56 6 4 6 o 6 9.0 6 OC S06 Ges ation 291 ib *Hemple Crustacezamess ss)» Ff ldas stekte ns meres 292 — UL, WOE GREENER 6 6 6 G GG 6 Oo Go 6 BD. 0 Bg. 6 pinhole uteri 293 XT. THE ARACHNOIDAE. Classification and Bibliography, . .......++s.+s+s++s2e-+--s 295 1. External Envelope, and Cutaneous Skeleton, .........- - - 296-397 2. Muscular System, and Organs of Locomotion,. ....... ° oe 2IS—209 3h INGIMOUS NEI, G od 60 6 9.0 c aie ERAS as tits te . . « » . 800-802 4. Organsiof Sense, . - . 5 2+ +. «s «+s EERE MC iisiicete isi ont 308-805 5. Digestive IA PPALALUS, lee tee) fe AG CO Ono btn Oa ONO. 3806-808 6. Circulatory Sis geo aaa db BO) Bp old) a clos o 6 +» « « « 809-310 Memes piratory Sy Stems: tile esiethe fie Yo es) (eiiodinet Rie ii= ioMo ula) lei otale 311-3813 ‘oh OmenicOt SERN 4g F Go Ud owa eo 5 o oo 4 5 ore 5 . . 814-315 i Whar? Oem, 5g 5) oo oo Beoud oO oO 0 9 0/8 so a5 c old If. Organs of Special Secretions, . .-..+ + +--+ + © « « « 315 Ch Orgasms Coaaehoy 5 G 5 bo 6 o 6 Oo On Go ac ooo) ae ys OLO—B20 I. Hermaphrodite Arachnoidae,. ....... Poor or a ies ee 317 ML emaile Arachnoidaes <<) «ter tesen oe ounces ceulle Mattel @M@ Mommie il= 318 NG WhiGwbeKdmmthesy 6 A Gg 5 5 5 5 6 ooo 0 oo 6 6 S855 319 XIV. THE INSECTA. Classification and Bibliography, © < 20. 7.) 2. 3 8 we 321 1. External Envelope, and Cutaneous Skeleton, .......2...-. Dees 2. Muscular System, and Locomotive and Soniferous Organs, ....- .- 325-327 By INGaGisishsmely —G Go cg Oa coo 5d a o.oo oO OG Gc 328-831 Ai Organs Of Senses t2! we , pele ys ae pe ved seas Greeny! =) espe! =), cl = nal oie 382-336 5. Digestive Apparatus, . . . 2. 6 2 2 6 2 eo ee ee te we es 3387-3839 GriCirculatory Systems st -0 =) wa) el) ee! el ep el) io) oem rel els 340 W) Respiratory Systems 2 ec 0) 0) 20120 0) ti ay of iellie VinileiUiE ache Donia Poe 341-844 B.lOrgans of Secretion, «. oi 0.2, ox 6 6s.00, sy oie oy oie) H athiol fel Het velllalte 345-847 AeUximary, Orgams.s «+

ch icilise en oh oy omen tone) (olSSo lon fo Molle elle 345-346 II. Organs of Special Secretions, . . - -- 2+ se ee ee eee 847 9. Organs of Generation,. . .. ++ +++ o) ok 0: oiler qe Mather MepesO4S=900 J. Female Genital Organs, ....... sirot lish tonto, 1e'gits cite tis HelfepotO—3 bil II. Male Genital Organs, PERG ack aren Can MTiy i 3 rig fea ip. 852-354 CLASSIFICATION OF THE INVERTEBRATE ANIMALS. § 1. Tue invertebrate animals are organized after various types, the limits of which are not always clearly defined. There is, therefore, a greater number of classes among them than among the vertebrates. But, as the details of their organization are yet but imperfectly known, they have not been satisfactorily “classified in a natural manner. There are among them many intermediate forms, which make it difficult to decide upon the exact limits of various groups. The following division, however, from the lowest to the highest forms of organization, appears at present the best : ANIMALIA EVERTEBRATA. INVERTEBRATE ANIMALS. Brain, spinal cord, and vertebral column, absent. FIRST GROUP. PROTOZOA. Animals in which the different systems of organs are not distinctly sep- arated, and whose irregular form and simple organization is reducible to the type of a cell. Cuass I. Inrvsorta. Cuass II. Rutzoropa. SECOND GROUP. ZOOPHYTA. Animals of regular form, and whose organs are arranged in a ray-like manner around a centre, or a longitudinal axis; the central masses of the nervous system forming a ring, which encircles the cesophagus. Cuass IIL. Potyret. Crass [V. AcaLreru™. Crass V. EcuHinoperRMATA. 16 CLASSIFICATION. § 2. THIRD GROUP. VERMES. Animals with an elongated, symmetrical body, and whose organs are arranged along a longitudinal axis; so that right and left, dorsal and ventral aspects may be indicated. The central nervous mass consists of a cervical ganglion, with or with- out a chain of abdominal ganglia. Cuass VI. HeEtmintHes. Ciass VII. Toureennarq. Crass VILL. Rorarorit. Cruass TX. ANNULATTI. FOURTH GROUP. MOLLUSCA. Animals of a varied form, and whose bodies are surrounded by a fleshy mantle. The central nervous masses consist of ganglia, some of which surround the cesophagus, and others, connected by nervous filaments, are scattered through the body. Cuass X. ACEPHALA. Cuass XI. CrpHaLopHora. Crass XI. Cepuatopropa. PIP RE GROUP. ARTHROPODA. Animals having a perfectly symmetrical form, and articulated organs of locomotion. The central masses of the nervous system consist of a ring of ganglia surrounding the cesophagus, from which proceeds a chain of abdominal ganglia. Crass XIII. Crusracna. Cuass XIV. ARracHNipA. Cuass XV. Insecta. BIBLIOGRAPHY. a2, Besides the various ancient and modern works upon general comparative anatomy, —such as those of Blumenbach,” G. Cuvier, F. Meckel,® E.. Home, Blainville,” Delle Chiaje,® Carus, Grant,® Rymer Jones,” Strauss 1 Handbuch der vergleichenden Anatomie. Git- 5 De POrganisation des Animaux, ou Prineipes tingen, 1824. j d@ Anatomie comparée. Tom. I. Paris, 1852. 2 Lecons d’Anatomie comparee. Paris, 1799- 6 Istituzioni di Anotomia e Fisiologia Comparata. 1805. Translated into German and published with Napoli, 1832. y notes and additions by Meckel and Froriep. 4 vols. 7 Lehrbuch der vergleichenden Anatomie. 2nd Leipzig, 1809-10. 2nd edit. Paris, 1835-45. ed. Leipzig, 1834. 3 System der vergleichenden Anatomie. 6 vols. 8 Outlines of Comparative Anatomy. London, Halle, 1821-33. 1841. o 4 Lectures on Comparative Anatomy. 6 vols. % A General Outline of the Animal Kingdom, and London. 1814-29. Manual of Comparative Anatomy London, 1841. BIBLIOGRAPHY. ni fa ( $ 2. Durckheim,™ R. Wagner,“— there exist various contributions upon the relations of these animals in the physiological works of Treviranus,"” Ru- dolphi, Dugés,™ Burdach,® J. Miller,“ R. Wagner," and in the Medical Zoology of Brandt and Ratzeburg. The iconographic illustrations by Carus and Otto, and by R. Wag- ner, contain many plates representing these animals; and in Guerin’s Iconographie,“ and Cuvier’s Régne Animal, edited by several French naturalists, are many illustrations of their internal structure. The following are some of the anatomical works which treat specially upon these animals : Schweigger.— Handbuch der Naturgeschichte der skelettlosen unge- gliederten Thiere. Leipzig, 1820. Delle Chiaje.—Memorie su la Storia e Notomia degli Animali senza Vertebre del regno di Napoli. 4 vol. Napoli, 1828-29. 109 tavole. A second and enlarged edition of this memoir has been published under the following title: Descrizione e notomia degli animali invertebrati della Sicilia citeriore. J—5, vol. Napoli, 1841. Con tavol. [-CLXXII. Sars. — Beskrivelser og Jagttagelser over nogle moerkelige eller nye 1 Havet ved den Bergenske Kyst levende Dyr af Polypernes, Acalephernes, Radiaternes, Annelidernes og Molluskernes Classer. Bergen, 1835. Lamarck. — Histoire Naturelle des Animaux sans Vertébres. édit., par Deshayes et Milne Edwards. 11 vols. Paris, 1835-45. Milne Edwards. — Klémens de Zoologie, ou Legons sur |’Anatomie, Ja Physiologie, la Classification, et les Moeurs des Animaux. Deux. édit. Animaux sans Vertébres. Paris, 1843. Richard Owen. — Lectures on the Comparative Anatomy and Physiology of the Invertebrate Animals. London, 1843. H. Frey and R. Leuckart. — Beitrage zur Kenntniss wirbelloser Thiere mit besonderer Berticksichtigung der Fauna des norddeutschen Meeres. Braunschweig, 1847. These same naturalists have prepared the second part of Wagner's Lehrbuch der Zootomie, under the special title of: Lehrbuch der Anatomie der wirbellosen Thiere. Leipzig, 1847. Stef. Andr. Renier. — Osservazioni postume di Zoologia adviatica pub- blicate per cura dell’ istituto veneto di scienze, lettere ed arti a studio del Prof. G. Meneghini. Venezia, 1847. Con tavol. I-XVLI. Deux. 10 Traité pratique et théoretique d’Anatomie 17 Lehrbuch der Physiologie. 2nd edit. Leipzig, comparée. 2vol. Paris, 1842. 1843. 11 Lehrbuch der Zootomie. 2nd edit., entirely re- vised ; or “‘ Lehrbuch der vergleichenden Anato- mie.” Leipzig, 1842. 12 Biologie. 6 vol. Géttingen, 1802-22. Also; Erscheinungen und Gesetze des organischen Le- bens. 2 vol. Bremen, 1831--33. 18 Grundriss der Physiologie. 2 vél. 1821-28. 14 Traité de Physiologie comparée de Homme et des Animaux. 3 vol. Montpellier, 1838-39. 1s Die Physiologie als Erfahrungswissenschaft, erste Auflage, mit Beitragen von C. v. Baer, Dieffenbach, J. Miller, R. Wagner. 6 vol. Leipzig, 1826-40. 2 te Auflage, mit Beitragen von E. Meyer, H. Rathké, C. v. Siebold und G. Val- entin. 2 vol. Leipzig, 1835-37. 16 Handbuch der Physiologie des Menschen. 2 vol. 4th edit. Coblentz, 1844. Berlin, 2% 18 Medicinische Zoologie. 2 vol. Berlin, 1829-83. 19 Erlauterungstafeln zur vergleichenden Anato- mie. 6heft. Leipzig, 1826-43. 20 Icones physiologicee. Erlaéuterungstafeln zur Physiologie und Entwickelungsgeschichte. Leip- zig, 1839. Also, Icones Zootomice. Handatlas zur vergleichenden Anatomie. Leipzig, 1841. 21 Tconographie du Régne Animal de G. Cuvier, ou Représentation d’aprés nature de lune des espéces les plus remarquables et souvent non en- core figurées de chaque genre d’?Animaux; pour servir d’atlas & tous les Traités de Zoologie. 7 vol. avec 450 planches. Paris, 1850-388. 22 Régne Animal de Cuvier, nouvelle édition, ac- compagnée de planches grayées, &c. &c. Paris, 1836-47. Still unfinished. INTRODUCTORY NOTE TO THE INFUSORIA. Constant labors in the whole department of microscopy, and that, too, with greatly improved instruments, during the past few years, have materially changed the face of the class Infusoria since the issue of this work. There have been numerous and signal researches among all the lower forms of animal life; and the imperfect and undeveloped forms of others, which are higher, have been wrought out with an accuracy and detail before unknown. These movements have all tended to diminish the numbers of the so- called Infusoria, and it remains to be seen how large the proper class will be when these researches shall have been further extended. By some even it is believed that it will be entirely resolved into other classes ; this view, however, would appear far from being warranted by our present knowl- edge; for, while, on the one hand, whole genera have been shown to be only larval worms (Bursaria, Paramecium, &c., from Planaria ),* yet, on the other, some forms have manifested phenomena and changes leading us to place them almost unhesitatingly among individual animals. In its best aspects, however, the subject has many perplexing points; and, in its present unsettled state, it is almost hazardous for a scientific man to entertain anything like positive views thereon. I need scarcely allude to the vegetable, algous character which whole sec- tions of the Polygastrica have recently assumed ; and the limits of this work will not allow me to discuss in detail this and other interesting points. But there are two or three topics of the highest physiological import, which are prominently introduced by these studies. These are, What is a plant? What is an animal? and, Are the animal and vegetable kingdoms on their lowest confines separate and distinct from each other ? As is well known, all the older criteria by which animals were separated from plants have long since been regarded invalid; and some of those which in late years have been regarded among the most constant, have, quite recently, been declared as equally unsound. Cellulose has been shown to be a component of animal as well as of vegetable structures, and Kiélliker + has insisted that some forms which have neither mouth nor stom- *Agassiz, Ann. Nat. Hist. VI. 1850, p. } Kélliker. Siebold and Kélliker’s Zeitsch. 156. I. 1849, p. 198. INTRODUCTORY NOTE TO THE INFUSORIA. 19 ach, but consist of a homogeneous mass, are true animals. If these premises are correct, nothing will remain, as I conceive, for a distinctive characteristic, but voluntary motion. This, when positive, is indubitable evidence of any given form being of an animal character; and it must remain for each individual observer to determine what is, and what is not, voluntary action, in each particular case. Moreover, even should Kédli- ker’s view of a stomachless animal prove correct, the inverse condition of a true stomachal cavity being present,must, I think, be regarded as posi- tive evidence of the animal nature of the form in question; for this must always be a distinctive characteristic of the two kingdoms, when present. In regard to the other point, What constitutes an animal? observers are very far from being agreed. Svebold, Kclliker, and others, have taken the ground that individual animal forms may be unicellular; or, in other words, that an animal may be composed of only a single cell.* This view is principally due to Kolliker’s observations and statements upon Gregari- nae.t The facts are indeed striking, but the evidence does not appear to me sufficient, as yet, to settle such a vexed and important question; and “more especially so since Bruch t has raised the point of their belonging to the Worms. But, aside from such grounds, I was led, some time since, after considerable study of infusoria-forms, to venture an opinion quite at variance with that just mentioned of Szedo/d and Kclliker. I then made the following statement: In regard to the question, What characteristic in organic animal matter shall constitute an individual? I feel satisfied of this mach, — that cell processes, however closely interwoven they may be with the expressions of individual life, cannot be considered as constituting the ground-work of its definition.§ This statement was made more than two years since; and subsequent observations, some of them of a special char- acter, have not led me toa change of opinion. ‘True individual animal life seems to involve a cycle of relations not implied in simple cells; in other words, these last must always lose their character as such, in a definite form which belongs to the individual. On thisaccount I regard the Infusoria proper, or those which have been shown to be of an undoubted animal character, as in a completely transition state; and, although it may be well to arrange these forms systematically, for the sake of convenience, yet they cannot be considered as holding fixed zodlogical positions.. Further research in this direction, and upon “ Alternation of Generation,” will, I think, widely clear up this obscure, yet most interesting field of study. Eprror. * Siebold. sSiebold and Kélliker’s Zeitsch. + Bruch. WSiebold and Kolliker’s Zeitsch. I. p. 270. If. p. 110. + Kolliker. Stebold and Kélliker’s Zeitsch. § Burnett. Proceed. Boston Soc. Nat. Wot oad le Hist. V. p. 124. BOOK FIRST. INFUSORIA AND RHIZOPODA. CLASSIFICATION. § 3. Tue Infusoria, using this word in a restricted sense, are far from being the highly-organized animals Ehrenberg has supposed. In the first place, on account of their more complicated structure, the Rotifera must be quite separated from them, as has already been done by Wiegmann, Burmeister, R. Wagner, Milne Edwards, Rymer Jones, and others. The same may be said of the so-called Polygastrica. In fact, a great number of the forms included under Closterina, Bacillaria, Volvocina, and others placed by Ehrenberg among the anenteric Polygastrica, belong, properly, to the vegetable kingdom. Indeed, this author has very arbitrarily taken ‘for digestive, sexual, and nervous organs, the rigid vesicles, and the colored or colorless granular masses, which are met with in simple vegetable forms, but which are always absent in those low organisms of undoubtedly an animal nature. Cell-structure and free motion are the only two character- istics in common of the lowest animal and vegetable forms; and since Schwann has shown the uniformity of development and structure of animals and plants, it will not appear strange that the lowest conditions of each should resemble each other in their simple-cell nature. As to motion, the voluntary movements of Infusoria should be distinguished from those which are involuntary, of simple vegetable forms ; a distinction not insisted upon until lately. Thus, in watching carefully the motions of Vorticellina, Trachelina, Kolpodea, Oxytrichina, &c., one quickly per- ceives their voluntary character. The same is true of the power of con- tracting and expanding their bodies. But in the motions of vegetable forms other conditions are perceived ; and there is no appearance of volition in either change of place or form, their locomotion being accomplished either by means of cilia, or other physical causes not yet well understood. Cilia, therefore, belong to vegetable as well as to animal forms, and in this connection it is not a little remarkable that in animals they should be under the control of volition. With vegetable forms these organs are met with either in the shape of ciliated epithelium, as upon the spores of Vaucheria,” or as long, waving filaments, as upon the earlier forms of many confervee,® in which last can 1 Mikroskopische Untersuchungen, &c. Berlin, teurs des spores des Algues. Ann. des Sc. Nat, 9 Botan. 1843, XIX. p. 266. Pl. XI. fig. 29-30. 2Thuret. Recherches sur les organes locomo- 3'The same. Pl. X. * $$ 4, 5. INFUSORIA AND RHIZOPODA. 21 often be seen the so-called organization of Ehrenberg’s Monadina and Volvocina. Until the fact that ciliated organs belong to both animals and vegetables was decided, the real place of many low organisms had to remain undetermined.” However, notwithstanding their free motion from place to place by means of cilia, the vegetable nature of many organisms seemed clearly indicated by the rigid, non-contractile character of their forms. It is from a misapprehension of the true nature of these facts, that» some modern naturalists have denied the existence of limits between the two kingdoms. With Bacillareze and Diatomacez, this question has another aspect. Many of these organisms have been taken for animals from their so-called voluntary movements, which truly entirely want the character of volition. In the movements of the rigid Diatomaceze, for instance, the whole plant has oscillatory motions like a magnetic needle, at the same time slightly changing its place forward and backward. When small floating particles come in contact with such an organism, they immediately assume the same motion. This may be well observed with the Oscillatoria. There are here, undoubtedly, no ciliary organs; in fact, they could not, if pres- ent, produce this kind of motion. According to Ehrenberg,” the Naviculae can protrude ciliary locomotive organs through openings of their carapace ; but this has not been observed by other naturalists. § 4. The Rhizopoda, whose internal structure is as yet imperfectly known, are closely allied to the Infusoria. Like these last, their bodies are cellu- lar, containing nuclear corpuscles, but no system of distinct organs. These two classes of Protozoa differ, however, in their external form, and the structure of their locomotive organs. The body of the Infusoria, notwith- standing its contractility, has a definite form, and moves chiefly by means of vibratile organs. That of the Rhizopoda, on the other hand, although equally contractile, has no definite form; their movements also are not due to ciliated organs, but to a change of the form of the body by various prolongations and digitations. § 5. Owing to the present incomplete details upon the organization of these animals, little can here be said about them; and therefore, instead of devoting to them a separate chapter, it will be proper to treat of them with the Infusoria in general. As the division of the Polygastric Infusoria, by Ehrenberg, into two Ueber die Verwandlung der 4 Asan example, may be mentioned the various Nordhausen, and dissimilar opinions of naturalists upon the Also, Kitzing, Infusorien in niedere Algenformen. question of the animal or vegetable nature of the “red snow ;” a question upon which Flotow, after the most careful studies, is still undecided. See Flotow, ‘Ueber Haematococcus pluvialis, ” in Noy. Act. Acad. Leop. Carol, vol. XX. part ii. p. 18. &See Unger, Die Pflanze im Momente der Thierwerdung. Wien. 1843. 1844. oe In an academic paper (Dissertatio de finibus inter regnum animale et vegetabile constiluendis, Erlangae, 1844), I have attempted to show that this confusion between the two kingdoms does not exist. 6 Abhandlungen der Akademie der Wissen- schaften zu Berlin, 1836, p. 184, Taf. I. fig. 19, and 1839, p. 102, Taf. IV. fig. 5. * 22 INFUSORIA AND RHIZOPODA. § 5. orders, Anentera and Enterodela, appears unfounded, the following class- ification seems more natural: ; PROTOZOA. Cimse ENFUSORIA. Organs of locomotion chiefly vibratile. ORDER I. ASTOMA. Without an oral aperture. Famity: AsTastaba. Genera: Amblyophis, Euglena, Chlorogonium. Famity: PrriinakA. Genera: Peridinium, Glenodinium. Famity: Oparrnana. Genus: Opalina. ORDER I. STOMATODA. With a distinct oral aperture and cesophagus. FAmIty: VORTICELLINA. Genera: Stentor, Trichodina, Vorticella, Epistylis, Carchesium. Famity: Opurypina. Genera: Vaginicola, Cothurnia. Famity: Encuetta. Genera: Actinophrys, Leucophrys, Prorodon. Famity: TRACHELINA. Genera: Glaucoma, Spirostomum, Trachelius, Loxodes, Chilodon, Phialina, Bursaria, Nassula. * Faminy: Koxnpopra. Genera: Kolpoda, Paramecium, Amphileptus. Faminty: OxyrricHina. Genera: Oxytricha, Stylonychia, Urostyla. Famity: Evuptora. Genera: Euplotes, Himantophorus, Chlamidodon. . $ 5. INFUSORIA AND RHIZOPODA. 23 Clipase JRE Z.0 Poms. Organs of locomotion consisting of completely retractile, ramifying prolongations of the body. ORDER I. MONOSOMATIA. Famity: AMOEBAEA. Genus : Amoeba. Famity: ARCELLINA. Genera: Arcella, Difflugia, Gromia, Miliola, Euglypha, Trinema. ORDER I. POLYSOMATIA. Genera: Vorticialis, Geoponus, Nonionina.” BIBLIOGRAPHY. O. F. Midler. Animalcula Infusoria. Hafnize, 1786. Ehrenberg. Die Infusionsthierchen als vollkommene Organismen. Leipzig, 1838. Also his numerous and important memoirs upon the Infusoria and Rhizopoda in the Memoirs of the Berlin Academy, and its Monthly Bulletin. Andrew Pritchard. A History of Infusoria, living and fossil, arranged according to the “Infusionsthierchen,” of Ehrenberg. Illustrated by nearly 800 colored engravings of these curious creatures, highly magnified. London, 1841. Kutorga. Naturgeschichte der Infusionsthierchen, vorziiglich nach EA- renberg’s Beobachtungen bearbeitet. Calsruhe, 1841. Dujardin. Histoire Naturelle des Zoophytes. Infusoires, Paris, 1841. This work treats also of the Rhizopoda. ADDITIONAL BIBLIOGRAPHY. Besides the various articles quoted in the additional notes I have made, the following are among the more important recent writings on this subject: Cohn. Beitrage zur Entwickelungsgeschichte der Infusorien, in Szedold & Kolliker’s Zeitsch. III. Hft. 3, and LV. Hft. 3. Ecker. “ur Entwickelungsgeschichte der Infusorien, in Szebold & Kal- liker’s Zeitsch. III. Hft. 4. Stein. Neue Beitr. zur Kenntn. d. Entwickelungsg. u. d. feineren Baues d. Infusionsthiere, in Siebold & Kolliker’s Zeitsch. III. p. 475. Pritchard. A History of Infusorial Animalcules, living and fossil, &c., with illustrations, new edition. London, 1852. See also numerous notes in the Annales des Sciences Naturelles, since 1847.— Eb. 1Jn this table are mentioned the families and genera of those only which have been the objects of anatomical study. 24 INFUSORIA AND RHIZOPODA. $$ 6, 7, 8. Class: Pel rie aL. EXTERNAL COVERING. § 6. The Protozoa are surrounded by a very delicate cutaneous envelope, which is sometimes smooth, and sometimes covered with thickly-set cilia.” Generally these cilia are arranged in longitudinal rows; but in Actino- phrys they consist of long contractile filaments of a special nature. CHAPTER (EL. MUSCULAR SYSTEM AND LOCOMOTIVE ORGANS, § 7. With the Prorozoa a distinct muscular tissue cannot be made out, but the gelatinous substance of their body is throughout contractile. It is only in the contractile peduncle of certain Vorticellina, that there can be perceived a distinct longitudinal muscle, which, assuming a spiral form, can contract suddenly like a spring. § 8. Tue Visratire Oreans on the surface of Infusoria serve as organs of locomotion. With many species they are found much developed at certain points, and are arranged in a remarkable order and manner. With Pertdinium, a crown of them encircles the body; with Stylony- chia, they are quite long, and surround the flattened body like a fringe ; while the Vorticellina have the anterior portion of their body surrounded by retractile cilia, arranged in a circular or spiral manner. In T'richodina there is, upon the ventral surface, besides a crown of these cilia upon the back, a very delicate ciliated membranous border, which is attached to a ring which is dentated, and composed of a compact homogeneous tissue. With Trichodina pediculus this border is whole and entire; but it is broken or ragged with Trichodina mitra.” By means of this organ these animals swim with facility, or invade with skill the arm-polyps and Planaria.” With many Infusoria, the vibratile organs are situated at the anterior extremity of the body, as simple or double non-retractile filaments, which move in a manner to produce a vor- 1 Euglena, Ameba, &c. 1 This Infusorium was discovered by me as a 2 Trachelius, Paramecium, Nassula, &c. parasite in many Planarieae. u 3 Amphileptus, Chilodon, Opalina, &c. 2 Ehrenberg has entirely overlooked the ciliated 1The peduncle is simple with Vorticella, but border of T'richodina pediculus, and has regarded ramified with Carchesium. With Epistylis it is the stiff serrations of the ring as movable hooks. not muscular. : See “ Die Infusionsthierchen,” p. 206. $5.9), 1:0: INFUSORIA AND RHIZOPODA. 25 tical action of the water. But with others the locomotive organ is a long retractile proboscis. With the Oxytrichina and Euplota, there are fieshy movable points (uNcINI) upon the ventral surface, by which these animals move about as upon feet. During these movements with the Oxy- trichina, the posterior portion of the body is supported by many setose and styloid processes, which point backward. The singularly varied and branching locomotive organs of the Rhizo, poda are short, and digitated with Ameba, Difflugia and Arcella.® But i in the other genera they are elongated and filamentous. CHAPTERS TIE: AN DEY. NERVOUS SYSTEM AND ORGANS OF SENSE. § 9. Although the Infusoria clearly evince in their actions the existence of sensation and volition, and appear susceptible of sensitive impressions, yet no nervous tissue whatever has as yet been found in them. If Ehren- berg supposed the Polygastric Infusoria to possess a nervous system, he did so because, having decided that the red pigment points of these ani- mals were eyes, he inferred that they a had a nervous ganglion at their base. , § 10. With the naked Infusoria the sense of touch exists, undoubtedly, over the whole body. But beside this, it appears specially developed, in many species, in the long cilia forming vibratile circles, or in those movable foot-like and snout-like prolongations of the body. In the same manner, it is probable they have the sense of taste also; for they seem to exercise a choice in their food, although no gustatory organ has yet been found. All species, whether they have red pigment points or not, seem affected by light. Without doubt, therefore, their vision consists simply in discrimi- nating light from darkness, which is accomplished by the general surface of the body, and without the aid of a special optical organ. The simple pigment point of many Infusoria,® and which Ehrenberg has generally regarded as an eye,“ has no cornea, and contains no body capa- ble of refracting light ; there is, moreover, connected with it no nervous substance. Ehrenberg attaches here too great an importance to the red color of the 3 Amblyophis, Euglena and Peridinium, have 8c. Nat. Zool. IV. 1835, p. 343, pl. IX.; also, V. a simple flagelliform cilium, but with Chlorogo- nium it is double. 4 Trachelius trichophorus feels about with a long snout of this kind, without, however, produc- ing a vortical action on ‘the water. 5 See Ehrenberg, ‘Die Infusionsthierchen,” Taf. VIII. and IX. 6 Gromia fluviatilis, Miliola vulgaris, Vor- ticialis strigtlata, Euglypha tuberculosa, Tri- nema acinus, according to Dujardin (Ann. des 1836, p. 196, pl. IX. fig. A. See, also, his Histoire des Infusoires, 1841, p. 249. pl. I. fig. 14-17; pl. Il. fig. 1, 2, 7—10; pl. IV. fig. 1); Geoponus stel- la borealis, Nonionina germanica, according to Ehrenberg. Abhand. d. Berliner Akad. 1839, p. 106, Taf. I. II. 1 Amblyophis, Euglena, Chlorogonium, &c. 2 Abhandl. d. Berliner Akad. 1831, p. 125 also, “ Die Infusionsthierchen,” p. 491. 26 INFUSORIA AND RHIZOPODA. $$ 11, 12. pigment,® for the blue, violet and green pigments, seen in the eyes of in- sects and crustacea, show clearly that the red pigment is not essential to the eye.* QHAPTER V. DIGESTIVE APPARATUS. Suk The Infusoria are nourished, either by taking solid food into the interior of their body, or by absorbing by its entire surface nutritive fluids which occur in the media in which they live. This last mode is illustrated in the Astoma, which have no distinct oral aperture or digestive apparatus. By the ingenious experiment first per- formed by Gleichen,”? of feeding these animals with colored liquids, no trace of these organs could be found. Ehrenberg, who also had observed that they did not eat, regarded their internal vesicles as stomachal organs, which were in connection with the mouth by tubes. The correctness of this opinion, however, has not been verified. Indeed, the genus Opalina® refutes it; here the species are quite large and visible to the naked eye, yet an oral aperture can be detected up- on no part of their body, and never do they admit into its interior colored particles. Solid substances found in them cannot be regarded as food. That fluids are here introduced by surface-imbibition is shown by Opalina ranarum ; this animal is found in bile in the rectum of frogs, and assumes a green color. When Opalina requiring only a certain quantity of liquid are placed in water, they quickly absorb it, become greatly swollen, and shortly after die. In such cases, the absorbed liquid is seen as clear, vesicular globules under the surface, and these globules have been taken by Ehrenberg as stomachal vesicles (vENTRICULI), and by Dujardin as VACUOLAE. § 12. Those Infusoria which are nourished by solid food have a mouth at a cer- tain place, and an cesophagus traversing the parenchyma of the body. Through this last the food is received, and is finally dissolved in the semi-liquid parenchyma of the body, without passing through stomachal or intestinal cay- ities. In many cases there is at the end of the body opposite the mouth an anus, through which the refuse material is expelled. But, when this is 2The genus Opalina was first established by Purkinje & Valentin. Many species are found in the rectum of frogs, and itis not rare to meet 3“ Die Infusionsthierchen,” p. 492. 1 Auserlesene mikroskopische Entdeckungen, 1777, p. 51; also, Abhandlung tiber die Saamen- und Infusionsthierchen, 1778, p. 140. * Some recent researches of T’huret (Ann. d. Sc. Nat. 8rd ser. XIV. 1850) on the reproductive germs of Algae prove that these bodies have red eye- like specks, resembling those seen in the Polygas- trica, but which disappear when the Zoospores at- tach themselves and germination proceeds. The with them in the alimentary canal of Planarieae.f fact is a very interesting one in this connection. — Ep. +[§ 11,note 2.] According to Agassiz (Amer. Jour. Sc. XIII. 1852, p. 425), Opalina is only a larval form of Distoma. — Ep. $ 12. a7 wanting, its function is often performed by the mouth. According to Ehrenberg, the Infusoria polygastrica, such as we have just been describ- ing, differ from the Infusoria rotatoria, in having a great number of stom- achs, which connect by hollow peduncles with the mouth in the division Anentera, and with the intestine in that of Enterodela. This organiza- tion, which, from its high authority, has generally been admitted by natu- ralists, is not, however, met with in any infusorium.” The vesicular cavities in the bodies of these animals, and which have been regarded by Ehrenberg as stomachal-pouches, never have a hollow peduncle, either connecting with the mouth (Aventera) or with the intes- tine (Enterodela). Indeed, it is doubtful if a digestive canal can be made out in these Infusoria. The vesicular, irregular contracting cavities of their body contain a clear liquid, evidently the same as that in which they live, which, with the Astoma, has been absorbed through the surface of the body. But, with those having a mouth and cesophagus, it is received through them, and taken up by the yielding parenchyma of the body. If the methods of feeding of Gleichen and Ehrenberg are employed, the colored particles are taken in by a vortical action of the water, caused by the cilia surrounding the mouth. This water, with its molecules, accu- mulates at the lower portion of the esophagus, and so distends there the parenchyma as to cause the appearance of a vesicle. Thus situated, the whole has much the aspect of a pedunculated vesicle. But when, from contractions of the cesophagus, this water escapes into the parenchyma, it appears there as aw unpedunculated globule, in which the colored particles still float. When the Stomatoda are full-fed in this manner, there appear many of these globules in various parts of the body; and thus sub- stances previously ingested are taken up and disseminated throughout the body. If the globules thus containing solid particles are closely aggregated, it sometimes happens that they fuse together; a fact which proves that they are not surrounded by a special membrane. The solid particles of food of the Stomatoda, which are often the lower Algae, such as the Diatomaceze and Oscillatoria,and often other Infu- soria, are sometimes deposited in the parenchyma without being surrounded, by a vesicular liquid.* From observations made upon Am@ba, Arcella and Difflugia, it appears that the Rhizopoda ingest their food like the Stomatode_Infusoria. INFUSORIA AND RHIZOPODA. neck. 1 Focke (Isis, 1836, p. 785) has already raised doubts as to the existence in Infusoria of the stomachs described by Ehrenberg. Ehrenberg has also opponents in Dujardin (Ann. des Sc. Nat. Zool. IV. 1835, p. 364; V. 1836, p. 193; X. 1838, p- 230; also Hist. Nat. des Infus. 1841, p. 57), in Meyen (Miiller’s Arch. 1839, p. 74) and in Ry- mer Jones (Ann. of Nat. Hist. IIT. 1839, p. 105; also, *‘ A General Outline of the Animal Kingdom,” 1841, p. 56). He has attempted to reply to the objections here urged by very detailed illustrations of the organ- ization of the Polygastrica, made by him and Wer- * Bailey (Amer. Jour. Sc. May, 1853, p. 341) has recently published an account, accompanied with numerous figures, of a new animalcule, which is so remarkable in this connection that I give here his description. He says: “If the reader will ( Muller’s Arch. 1839, p. 803; also Monats- bericht der Berliner Akad. 1541, p. 103.) But, de- tailed as they may he (see Elirenberg Abhandl. d. Ber. Akad. 1830, Taf. I11.; 1831,‘Taf. 1IL.; also “Die Infusionsthierchen,” Taf. XXXII. XXXVI. and XXXIX.), they are not representations of nature. The organ whichin T'rachelius ovum has been taken by Ehrenberg (‘Die Infusionsthierchen,” p. 323, Taf. XX XIII. fig. xiii. 1) for a branching di- gestive tube, has always appeared to me only as a solid fibrous cord, traversing the soft parenchyma of the body, and by its ramifications presenting a coarse meshed aspect. imagine a bag made of some soft extensible mate- rial, so thin as to be transparent like glass, so soft as to yield readily to extension when subjected to internal pressure, and so small as to be microscop- ic ; this bag, filled with particles of sand, shells of 28 INFUSORIA AND RHIZOPODA. $$ 13, 14. § 13. If the vesicular cavities containing the liquid and colorless food of the Stomatoda be examined under the microscope by a horizontal central inci- sion, their contents appear colorless; but by changing the focus, viewing alternately the convex and concave surfaces of the vesicle, the points of junction between the colorless globules and the parenchyma appear colored pale-red. This appearance, due to an optical illusion, might easily deceive one into the opinion that the vesicles which are really colorless are colored. From this it is probable that Ehrenberg has described Bursaria vernalis and T'rachelius meleagris as having a red gastric juice.” The violet points which are found upon the back and neck of Nassula elegans and Chilodon ornatus are only collections of pigment granules, esa in the first case, are often absent, and in the second are often par- tially dissolved. This last violet liquid has been regarded by Ekrenberg® as a gastric juice resembling bile. § 14. The solid particles of food, whether surrounded by the parenchyma or enclosed ina liquid vesicle, are moved hither and thither in the gelatinous tissue of the body, during the contracting and expanding movements of the animal. In some, the parenchyma with its contained food moves in a reg- ularly circular manner, like the liquid contained in the articulated tubes of Chara. In Lozodes bursaria © this circulation is remarkable, and of much physiological interest. lts cause is yet quite unknown, for in no case is it due to cilia, and it may be observed in individuals entirely at rest. Ehren- berg,” therefore, is incorrect in regarding it as due solely to a contratile power of the parenchyma, displacing the molecules. Much less is his ex- planation “ satisfactory, since the digestive tube of an infusorium can be extended at the expense of its stomachal pouches, so as to fill the whole body, giving it the appearance of having a circulation of molecules through- out its entire extent. 1“ Die Infusionsthierchen,” pp. 321, 826, 329. Ehrenberg has, moreover, in T'rachelius melea- gris, confounded the contractile cavities with those non-contractile, and which receive the food. 2 Abhandl. d. Berliner Akad. 18338, p. 179 5 “Die Infusionsthierchen,” pp. 3819, 338, 339.* 1 Vaginicola and Vorticella. See Focke, Isis, also Diatomacee, portions of Algae or Desmidieae, and with fragments of variously colored cotton, woolen, and linen fibres, will give a picture of the animal ; to complete which, it is only necessary to add a few loose strings to the bag to represent the varia- ble radiant processes which it possesses around the mouth.” This animal, which is often found with bits of cotton protruding from its mouth, assumes the most bizarre shapes. They appear to multi- ply by fissuration and gemmation even when filled with these heterogeneous particles, and, on the whole, present characteristics as remarkable , as 1836, p. 786; also Meyen, Miiller’s Arch. 1839, p- 75. 2 Focke loc. cit.; also Erdl, Miiller’s Arch. 1841, p. 278. 8 Loc. cit. p. 262. 4 Miiller’s Archiv. 1839, p. 81. those of any animalcule with which we are ac quainted. — Ep. *[§ 13, note 2.) In this connection should be noticed the experiments of Will (Miuller’s Arch. 1848, p. 509). He found evidences of a biliary ap- paratus, with Vorticella, Epistylis, and Bursaria. These evidences are based on chemical reaction, and he describes no anatomical apparatus. I men- tion this fact here, although Vorticella belongs truly to the Bryozoa, and Bursaria to the Plana- ria. — Ep. $$ 15, 16. INFUSORIA AND RHIZOPODA. 29 § 15. The round or elongated oval mouth of Infusoria varies as to its posi- tion. Sometimes it is in front, sometimes behind ; and in some cases, near the middle third of the body. Rarely naked,” its borders are generally ciliated,” and often its circumference is provided with a very remarkable ciliary apparatus. By the aid of this, these animals not only move about; but when quiet produce vortical actions of the water, which are felt at quite a distance; and all minute particles within its reach are quickly drawn towards its mouth, and then swallowed or rejected according to the option of the individual.” It is rare that this oral aperture is provided with a dental apparatus. The oral cavity, generally infundibuliform, extends into a longer or shorter, straight or curved cesophagus, which is lined throughout by a very delicate ciliated epithelium.” The-anus, situated usually upon the dorsal surface of the posterior por- tion of the body, is sometimes, though rarely, indicated by a slight exter- nal projection. CHAPTERS Vis ASD VE. CIRCULATORY AND RESPIRATORY SYSTEMS. § 16. A vascular system entirely distinct by closed walls from the other organs is not found in the Protozoa. But with very many (with all the Stomatoda, without exception) there are contractile pulsatory cavities, the form, number and arrangement of which is quite varied. They are situated in the denser and outer layers of the parenchyma of the body, and during the diastole they become swollen by a clear, trans- parent, colorless liquid, which, during the systole, entirely disappears. 1 Actinophrys. The mouth is naked also in the genera Difflugia and Arcella of the Rhizopoda.* 2 Bursaria, Paramecium, Urostyla and Sty- lonychia. In Glaucoma scintillans the ciliated crown of the mouth is replaced by a special semi- lunar ciliated lobe. 3 In Stentor, Vorticella, Epistylis and Tricho- dina, this apparatus is retractile, and produces in a particular way the vortical actions. In Spirosto- mum ambiguum, there is a long, narrow, ciliated furrow, through which the food is conducted to the mouth, situated at the posterior portion of the body. 4 Prorodon, Nassula, Chilodon and Chlamido- don. Here the hair-like teeth are arranged in a cylinder so as to resemble a weir. 5 The cesophagus is short in Oxytricha, Sty- lonychia, and Euplotes ; but is elongated or spi- ral in Vorticella, Carchesium and Epistylis ; *[§ 15, note i.] KGlliker (Siebold and Kolli- ker’s Zeitsch. I. 1849, p. 198) has given a long and detailed description of Actinophrys sol. Accord- ing to him, it is without mouth or stomach proper, and internally is composed . a homogeneous sub- while it is long and arcuate in Bursaria trunca- tel/a and cordiformis. 6 The undigested matters accumulate about the anus, and when this opens are expelled from the parenchyma with a certain force. With Nassuda elegans, the greater or less portions of the Osci/- latoria gracillima (Kttzing) upon which it feeds, and which are of a blue-green color, dis- solve into granules of this color. But these, dur- ing the process of digestion, gradually assume a brown color, and form irregular masses in the pos- terior portion of the body, and are from time to time expelled as brown foeces. These green gran- ules are not therefore eggs, as Ehrenberg (loc. cit. p. 339) has supposed. This Nassu/a when young is perfectly colorless, with the exception of a beautiful blue spot. stance. Yet this remarkable animal lives on other Infusoria, Algae, &c., and avails itself of them by seizing and afterwards invaginating them in its pa- renchyma, until they finally are included within its interior. — Ep. 30 INFUSORIA AND RHIZOPODA. S17. These movements succeed each other at more er less regular intervals. When these cavities are numerous, a certain order in the succession and alternation of their contractions cannot always be observed. It is very probable that their liquid contained during the diastole is only the nutri- tive fluid of the parenchyma, and to which it returns during the systole. In this way it has a constant renewal, and all stagnation is prevented. This arrangement constitutes the first appearance of a circulatory system, and the first attempt at a circulation of nutritive fluids. From an optical illusion similar to the one mentioned as belonging to the vacuole ($ 15) the liquid of these pulsating cavities has a reddish hue. § 17. A round, pulsating cavity is found in the genera Vorticella, Epistylis, Loxodes, and in the following species: — Amada diffluens, Paramecium kolpoda, Stylonychia mytilus, Euplotes patella, §-c. With Actinophrys, Bursaria, Trichodina, there are from one to two; with Arcedla vulgaris, three to four ; with Nassua elegans, there are four placed in a longitudinal line on the dorsal surface. With Tvachelius meleagris, there is a series of eight to twelve upon the sides of the body, and with the various species of Amphileptus there are fifteen to sixteen arranged more or less regularly. With Stentor, there is a large cavity in the anterior portion of the body, and many similar cavities appear upon the sides, united sometimes into one long canal. A similar canal traverses the entire body of Spzrostomum ambiguum, and Opalina planariarum. With Paramecium aurelia, the two round cavities present a remarkable aspect, being surrounded by five or seven others, small and pyriform, the top of which being directed outward, the whole has a star-like appearance.’ During the pulsation, often the entire star disappears, sometimes only the two central cavities, and in some cases the rays only. These cavities, entirely disappearing in the systole, reappear in the dias- tole, and usually in the same place and with the same form and number. This would lead us to conclude that they are not simple excavations in parenchyma, but real vesicles or vessels, the walls of which are so excess- ively thin as to elude the highest microscopic power. In some individuals, as, for instance, with T'vachelius lamella, there appear, during the diastole, two or three small vesicles at the extremity of the body, which, after having increased in size, blend into one which is very large. These are probably only globules of nutritive fluid, separated from the parenchyma. Similar phenomena are observed in Phialina ver- micularis and Bursaria cordiformis. It sometimes happens with these animals that a forcible contraction of the whole body divides an elongated cavity into two spherical portions, as 1 Ehrenberg (loc. cit. p. 821, Taf. XX XIII. fig. viii.), deceived by this illusion, has taken the eight in the body. It really seems very strange that these animals should practise uninterruptedly these ‘These ani- to twelve contractile cavities of Trachelius melea- gris for stomachal cells, filled with red gastric juice. He has also regarded these cavities, when simple or double, as seminal vesicles. (Abhandl. d. Berliner Akad. 1833, p. 172,—1835 p. 158.) In species having but few, he has very arbitrarily decided that some are seminal vesicles, others stomachal pouches, as, for example, in Amphileptus (loc. cit. p. 850). According to him, the seminal vesicles, upon con- traction, pour the sperm upon the eggs contained pollutions throughout their entire life. mals have neither testicles nor ovaries, and the function of these cavities is not, therefore, that assigned to them by Ehvenberg,—but is, as I think, with Wiegmann (Arch. f. Naturg. 1835, I. p- 12), analogous to that of a heart. 1 Dujardin, Ann. d. Sc. Nat. Zool. tome X. Pl. XV. fig. 3; also, ‘‘ Infusoires,” Pl. VIII. fig. 6. Ehrenberg’s plates of these star-like vesicles are incorrect. $$ 18, 19. INFUSORIA AND RHIZOPODA. 31 though it were a drop of oil. The observation of these phenomena would make it doubtful whether or not these cavities are true vesicles or vessels. These cavities have been met with in only afew of the Astoma, and these are, Cryptomonas ovata and Opalina planariarum. G4) The Infusoria appear to respire solely by the skin. In those species whose. bodies are covered with vibratile cilia this function is promoted by the vortical action of the water caused by these organs. In others, the contractile cavities just described are situated immediately under the skin, and the opinion may be entertained that the water so communicates with their liquid contents as to perform a respiratory function. In this re- pect Actznophrys sol is quite remarkable, for its contractile cavities are so superficial that when filled they raise the skin in the form of aqueous vesicles,” which, however, are so elastic as entirely to disappear in the parenchyma. Here it is plain that a mutual relation between the external water and the contents of these cavities might easily take place. CHAPTER VIII. ORGANS OF SECRETION. § 19. No special organ of secretion has been found in the Protozoa ; their skin, however, has a power of secreting various materials, which in some species harden and form a carapace, or a head of a particular shape; while in others it serves to glue together foreign particles, forming a case, in which the animal retreats. Among those having a carapace, may be mentioned Vaginicola, Cothur- nia, and Arcella. This more or less hard envelope does not resist fire, and is probably of a corneous nature. In the Rhizopoda, however, it is usually calcareous, like the shells of Mollusca, and is not affected by heat. The Diflugiae carry about with them an envelope of this kind, composed of grains of sand. 2 Ehrenberg, loc. cit. p. 41, Taf. IT. fig. xvii. 1 Ehrenberg (Ibid. p. 303, Pat, XXXI, fig. vi. 1) appears to have taken the protrusion of these con- tractile vesicles for that of a ’snout. 32 INFUSORIA AND RHIZOPODA. $$ 20, 21, 22. CHAPTER IX. ORGANS OF REPRODUCTION. § 20. The Infusoria propagate by fissuration and gemmation, and never by eggs.” They have therefore no proper sexual organs. This fissuration occurs longitudinally with some,” transversely with others,® and in many of them by both at once.“ Gemmation, on the contrary, is very rare. § 21. Nearly all the Infusoria and Rhizopoda have in their interior a nicely- defined body, a kind of a nucleus, which is quite different, in its compact texture, from the parenchyma by which it is surrounded. This nucleus, which, in different species, varies much in number and form, performs an essential part in the fissuration. For, every time the individual divides either longitudinally or transversely, this nucleus, which is usually situated in the middle, divides also. So that, in the end, each of the two new individu- als has anucleus. When an animal is about to undergo fissuration, there is generally first perceived a change in the nucleus. Thus, in Paramecium, Bursaria and Chilodon, the nucleus is sulcated longitudinally or trans- versely, or even entirely divided, before the surface of the body presents any constriction. This nucleus, which is of a finely granular aspect and dense structure, re- tains perfectly its form when the animal is pressed between two plates of glass, and the other parts are spread out in various ways. By direct light its color appears pale yellow. It appears to lie very loosely in the parenchyma, and sometimes individuals may be observed turning their bodies around it as it rests motionless in the centre. From all this, it cannot be supposed that this nucleus attaches itself to other parts of the animal, and especially to the pulsatory cavities (Vesicule seminales of Ehrenberg). § 929, A simple, round, or oval nucleus is found in Euglena, Actinophrys, Arcella, Ameba, Bursaria, Paramecium, Glaucoma, Nassula and Chilo- don. But there are two which are round, and placed one after the other in Amphileptus anser and fasciola, in Trachelius meleagris, and Oxytri- cha pellionella. With Stylonychia mytilus, there are four. 1 That which Ehrenberg has arbitrarily taken for eggs is sometimes granules of the parenchyma or pigment corpuscles, sometimes bits of food. He did not perceive that these bodies want all that which is necessary to make up an egg, —such as chorion, vitellus, and germinative vesicle and dot. It is on this account that he declares that he never has observed the hatching of young Infusoria. (Ab- handl. d. Berliner Akad. 1835, p. 156.) 2 Vorticella, Carchesium. 3 This may be easily observed with Stentor, Leucophrys, Loxodes, and Bursaria. 4 Bursaria, Opalina, Glaucoma, Chilodon, Pa- ramecium, Stylonychia and Euplotes. 5 Vorticella, Carchesium and Epistylis. 1 Ehrenberg, loc. cit. Taf. XXXVI. fig. vii. 13 to 19, Taf. XX XIX. fig. ix. 4, 5, 11-13. 2 Ehrenberg, from a strange fancy, has taken this nucleus for a seminal gland. (Abhandl. d. Berliner Akad. 1835, p. 163. Also, loc. cit.) $ 23. 388 INFUSORIA AND RHIZOPODA. It is not rare that a variable number of these round nuclei, arranged in a row, traverse the body in a tortuous manner. This is so in Stentor coeruleus and polymorphus, in Sptrostomum ambiguum, and in Trachelius moniiger. In many instances the nucleus has the form of an elongated band, which is slightly curved in Vorticella convallaria, Epistylis leucoa, Prorodon niveus and Bursaria truncatella. In Stentor Reselii, it is spiral, and in Euplotes patella and Trichodina mitra, it is shaped like a” horse-shoe. In Loxodes bursaria, it is kidney-form, and encloses in one of its extremities a small corpuscle (nucleolus). . The round nucleus of Euglena viridis has in its centre a transparent dot. In Chilodon cucullulus, the nucleolus has a similar dot, and thus the nucleus as a whole resembles a cell. § 23. These nuclei, which make Infusoria resemble cells, deserve a special attention, since they do not die with the animal. Thus the nucleus of Euglena viridis, which, according to Ehrenberg,” is globular when dying, and surrounded by a kind of cyst, remains unchanged a Jong time, or even increases in size, having no appearance of a dead body. It may be that the life of this animal, under these circumstances, is not finished, but only assumes another form.@ 1 Loe. cit. p. 110. 2 Perhaps this nucleus, of which the animal is only a temporary envelope, is ultimately developed into a particular animal. Indeed, perhaps this species, as well as many others, are only the larval states of other animals, whose metamorphoses are yet unknown. It may properly be asked, if this nucleus has not, relative to the body containing it, the same signification as have the tubulous larve of Monostomum mutabile (see below) to the em- bryos they surround. That the nucleus contained in Infusoria plays an important part in the propagation of those animal- cules, is supported also by a recent observation of Focke, who witnessed the development of several young individuals in the nucleus of Loxodes bur- saria. See Amtl. Bericht tiber die 22 tr. Versaaml. deutsch. Naturforscher. in Bremen, Abth. ii. p. 110. INTRODUCTORY NOTE TO THE ZOOPHYTA. Wrrutn the past six or seven years the Zoophytes have received more attention from naturalists than any other division of the animal kingdom. The labors of many, if not most of our ablest naturalists, have been directed towards an investigation of the humblest forms of animal life. This fact, combined with the recent improved methods and means for research, would alone be prophetic of the most signal advances in this group ; indeed, our knowledge of all these forms has been so modified, as well as increased, that previous writings need rather to be re-written than revised. Dana, Agassiz, Milne Edwards, Forbes, Dalyell, Miller, Busch, and others, not to mention the continued labors of older observers, have effected these changes in this group. j The work of Dana is most excellent, and will remain a standard of au- thority in this department for a long time to come. Aside from the many details of structure, in it may be found the first and best philosophical exposition of the relations of organic development with these lower plant- like forms. Had this work been better known in Europe, there would have been saved the constant repetition of the most grave errors. On the labors of Agassiz no comment need be made; those who are in this department, whether as minute Anatomists or philosophical Zoologists, will not fail to understand and appreciate him. In the same field is Busch, who was extended his brief though excellent labors over the three classes of this whole group; as for the remaining authors mentioned, excepting Muller, their position in this department has long been established. Mudler’s researches have been mostly on the Echinoderms, and the careful tracing of the phases of their development and metamorphoses ; but where so much has been done, I fear the limits of this book will preclude full details with this class. This note would be unnecessary, were it not to show that I do not ignore the changes and advance which have been made in this group within the past few years; and more especially so, as I have allowed, in this edition, the classification to stand as in the original. Any great changes of this INTRODUCTORY NOTE TO THE ZOOPHYTA. 35 kind I could not think of making without the consent of the authors, who, although they would undoubtedly fully sanction them, are not sufficiently accessible to me just now, as these pages are going to press. So, however much the present classification may offend the eye of the Zoologist, yet the Anatomist will find under each head the proper details. Thus, he will find as full a description of the anatomical structures of the Bryozoa and Hiydroid Polypi, as though they were referred to the Mollusca and Acal- ephae, where truly they respectively belong. Eprror. BOOK.SECOND. PO.bY.2 4. CLASSIFICATION. § 24. Tur Potyrr are either immovably fixed, or seated on a locomotive foot. Their soft body is in part enveloped by a solid support, the polypary. This last is often, for the most part, horny or calcareous; and by it numbers of these animals are united into greater or less groups. The central mouth is always surrounded by a coronet of contractile tentacles. The digestive apparatus is organized after two different types, upon which is based a division of these animals into two orders. ‘The sexual appara- tus is always without copulatory organs. ORDER I. ANTHOZOA. The digestive canal is without an anus, and opens into the general cavity of the body. Famity : Mapreporina. Genera: Oculina, Millepora, Madrepora, Caryophyllia, Astraea, Desmo- phyllum, Maeandrina, Monticularia, Agaricia, Favia. Famity : GorGgonina. Genus: Gorgonia. Famity : Isrpra. Genera: Corallium, Isis. Famity: TuBIPoRINA. Genus: Tubipora. Faminty : ALCYONINA. Genera: Alcyonium, Lobularia, Alcyonidium. Famity: Prnnatuuina. Genera: Veretillum, Pennatula, Virgularia. $ 24. THE POLYPI. 3T Famity: SERTULARINA. Genera: Sertularia, Campanularia. Famity : ZoantTHIna. Genus: Zoanthus. - Famity: Hyprrina. Genera: Hydra, Eleutheria, Synhydra, Coryne, Syncoryne, Corymorpha. Famity: ActTInina. Genera: Actinia, Eumenides, Edwardsia. ORDER IL BRYOZOA. The digestive canal is closed from the general cavity of the body, and opens behind through an anus. Famity: Rereporina. Genera: Eschara, Cellepora, Flustra, Bicellaria, Retepora, Telegraphina, Tendra. Famity: ALCYONELLINA. Genera: Cristatella, Alcyonella, Bowerbankia, Vesicularia, Lagenella, Plumatella, Lophopus.” BIBLIOGRAPHY. Ellis. Essai sur |’Histoire naturelle des Corallines et d’autres produc- tions marines du méme genre. La Haye, 1756. Pallas. FElenchus zoophytorum. Hagae 1766. Cavolint. Memorie per servire alla storia dei polipi marini. Napoli, 1785. Rapp. Ueber die Polypen im Allgemeinen und die Aktinien insbeson- dere. Weimar, 1829. Ehrenberg. Die Corallenthiere des rothen Meeres, in the Abhandl. d. Berliner Akad. 1832. Johnston. A History of the British Zoophytes. Edinburgh, 1838. Besides the important work of Dana, which will be often quoted in my notes, the additions to the literature of the true polyps have been few since the issue of this work, and have generally been published in the form of articles in the various periodicals, to which reference will be made in my notes. But the Bryozoa have been specially studied, and particularly in the following papers : 1 There are here enumerated only those families This remark applies equally to the following whose organization has been specially studied. classes. 38 THE POLYPI. $$ 25, 26. Van Beneden. Recherches sur |’Anatomie, la Physiologie et le devel- oppement des Bryozoaires. Mém. Acad. Brux. Tomes XVIII. XIX. Recherches sur les Bryozoaires fluviatiles de Belgique. Ibid. Tom. XXI. For further literature on the Bryozoa, see the writings quoted in my notes, and especially those of Ad/man. Kp. CHAPTER I. CUTANEOUS ENVELOPE AND SKELETON. § 25. The Polypi are composed of either entirely soft parts, or have for their support a solid frame, which may be calcareous, corneous, or coriaceous. This frame is always the product of the general skin, and ought therefore to be compared to a cutaneous skeleton.* This skeleton, known by the name. of polypary, is formed partly internally, and partly externally, by these animals. In the first case it is called an azal, and in the second a tubular polypary. The axial polypary consists, with some polyps,” of a dense substance, apparently unorganized and composed of carbonate of lime; with others, of a corneous substance, equally unorganized. When the polypary is coriaceous, it is often covered by a variable number of calcareous, fusiform corpuscles, usually bossed or dentated.” With some calcareous polyparies this is also true, and then the corpuscles are arranged in compact reticu- lated masses. The tubular polyparies serve as a refuge for the animals living in them, and in many cases, being common to many individuals, these last are in direct relation to each other by the canals which traverse the branching tubes. In the axial polyparies there are often cavities or depressions of a variable size,® in which the animals can conceal them- selves. When, however, these are wanting,” they retire, as is the case with many soft polyps,® beneath their mantle. Sometimes,” these cavities are closed by a movable operculum. § 26. The skin of polyps is very transparent, and should be carefully dis- tinguished from the parenchyma which it envelops. It is smooth, or it is covered with ciliated epithelium. And, since it has been shown that many 1 The Actinina and Hydrina. 2 Corallium. 3 The Gorgonina. 4 These corpuscles are easily seen in Alcyonium and Lobularia. (Milne Edwards, Ann. d. Sc. Nat., Zool. LV. 1835, pl. XIII. fig. 9; Pl. XV. fig. 10--11.) Spicula of this kind are found in the interior of their tissues, as well as on the surface. Ehrenberg (Abhand. d. Berl. Akad. 1841, Th. I. *Tt should here be remarked that the old, and as now regarded, mistaken view of the formation of the frame of Polyps is here repeated; for the frame is generally an internal skeleton, as, for instance, p. 403, Taf. I.-III.) has described and figured these spicula under the names of Spongolithis and Lithostylidium. 5 The Madreporina. 6 Millepora, Madrepora, Oculina and Astraea. 7 Gorgonia, Isis and Corallium. 8 The Actiniae. 9 Eschara and Cellepora. with Madrepora, Astraea, &c. For the formation of Coral, see Dana, loc. cit.; and for the relations of the corallium carried out in detail, see Edwards and Haime, Ann, d. Sc. Nat. 1849, 750, ’51. — Ep. $$ 27, 28. THE POLYPI. 89 Anthozoa have the skin, and especially the tentacles, covered with cilia of this nature, these last cannot be regarded as forming a differential charac- teristic between them and the Bryozoa, as has been done by Ehrenberg.” § 27. The skin of many polyps is quite remarkable in having nettling or, poisonous organs, to which it is only of late that the attention has been directed. They consist of transparent vesicles, having a dense membrane, of a round, oval, or cylindrical form, containing a clear liquid, and a very delicate filament of variable length, which is usually spirally coiled. By the least irritation of the skin, the filament is thrown out of the vesicle, of which it appears to be only a prolongation. These filaments adhere to objects coming in contact with the skin, and in this way the vesicles in question are separated from it.” These organs are probably the cause of the nettling sensation felt when certain polyps are handled. § 28. Still more interesting are organs analogous to those just mentioned, and which belong to various species of Hydra. They are found not only on the arms, but also upon the skin of the body and foot. They consist of oval vesicles, having a very long and delicate filament, which is slightly swollen and viscous at its free extremity, while the opposite one is directly continuous with the conical neck of the vesicle. The neck of each vesicle is surrounded by three hooks curved backwards. These are always elevated when the skin of the animal is irritated, and especially that of the arms when they seize their prey. This last is then wound about by the free, viscous end of the filament, and the attached vesicle being torn from the body, the whole is often entangled in the arms of adjacent polyps. When this occurs, the vesicles hang by their hooks to the arms of the polyps; and it is this that has given Ehrenberg the opinion that the vesicles are detached by their round extremity, that these animals watch their prey with the hooks erected, and that the vesicles and filaments can return into the inte- rior of the arms.” But it is probable that they (the hooks) act more as poisonous than as prehensile organs ; for if those from the arm of a Hydra seize upon a lVais, a Daphnia, or alarva of Chironomus, these last quickly die, even if they escape immediately after being taken. 1 Erdl has seen very distinct ciliated epithelium in Actinia and Veretillum. (See Maiiller’s Arch. 1841, p. 423.) 2 Abhandl. d. Berl. Akad. 1834, p. 255, 377. 1 These nettling organs, which are much more common in the lower orders of the animal kingdom than was at first supposed, are yet quite imper- fectly known. Wagner first discovered them in the Actinia, although he regarded them at first as the spermatic particles of these animals. (Wieg- mann’s Arch. 1838, IL. p. 215, Taf IIL. fig. 7, also 1841, I. p. 41; Icones Zoot. Tab. XXXIV. fig. 24.) These researches have been extended by Erdi, who has shown that they also exist with Veretillum and Alcyonium. (Miuiller’s Arch. 1841, p. 423, Taf. XV. fig. 3--6 and 8,9.) In Alcyontum, Erdl has observed the filament take, on its departure from the vesicle, first a riband-like, and then a spiral aspect. In Desmophyllum stellaria (Ehrenberg), I have seen these cylindrical organs having a long spiral filament. With Edwardsia, Quatrefages has found these organs upon the whole surface of the body, as well as upon the arms. (Ann. d. Sc. Nat., Zool. 1842, XVIII. p. 81, Pl. Il. fig. 46.) For the nettling organs of the Tubulariae and the Actiniae, see also Wagner in Miiller’s Arch. 1847, p. 195, Taf. VILI. 1 These were first described by Ehrenberg. (Mittheil. a. d. Verhandl. d. Gesellschaft naturf. Freunde zu Berlin 2 tes. Quartal, 1836, p. 28 ; also, Abhandl. d. Berl. Akad. 1835, p. 147 ; 1836, p. 133, Taf. II.) They have been carefully studied by Erdi (Miiller’s Arch. 1841, p. 429. Taf. XV. fig. 10--13). 2 Ehrenberg has figured, ideally (Abhandl. d. Berl. Akad. 1836, p. 133, ‘af. II. fig. 1) an Hydra in the act of seizing its prey with extended hooks. In reality this animal is never thus seen, 40 THE POLYPI. § 28. These poisonous and prehensile organs are destroyed by use, which is also true of the nettling organs. speedy reproduction. But this loss is probably repaired by their This last circumstance may explain the various descriptions given them by different authors, for, probably they have been observed at dissimilar stages of development. 3 Erdl, who has discovered a great number of these nettling organs, saw, in some cases, the thread directly continuous with the neck of the vesicle ; in others, these necks appeared furnished with spines directed backwards; exactly as Wagner had before described, and as Kélliker had often ob- * [§ 28, note 3.] These nettling organs of the Polypi have recently been very successfully studied by Agassiz, who has enjoyed the most enviable advantages with the Polypi and Acalephae of the North American coast. He has changed the entire aspect of the subject, besides almost exhausting it for future research. His special studies were made on the coral polyp of our southern coast, the Astrangia Danae, Agass. The complexity of structure of these lasso-cells, as he has very appropriately termed them, is truly wonderful for such minute forms. As I have also studied these forms, I will uso my own language, in the description of what Prof. Agassiz has seen. There are several varieties of these cells or capsules, depending upon the ar- rangement and structure of the lasso ; sometimes this last is a simple coil, sometimes it is coiled about a staff which is erected from the base, but which is also a part of the projectile apparatus. In the first case, the lasso is much the longer and may be fifty or seventy-five times the length of the vesicle; while, in the second case, it rarely exceeds the length of this last by more than sixteen or twenty times. In all cages, the essential feature of these organs is the lasso or internal coil, which is of a most curious structure. In the first place, it is, in general terms, only an inverted portion of the vesicle or cell itself, an internal instead of an external cilium, coiled up in a regular manner. When thrown out, there- fore, it is wholly inverted, and its projection consists “of an instantaneous turning of the whole inside out. But the lasso, delicate as it is, has still more delicate structures on its surface. These consist of barbels arranged in regular spiral rows, which extend to the very extremity of the lasso. At this last served (Beitrige z. Kenntniss d. Geschlechtsver- hAltnisse u. d. Samenfltissigkeit wirbelloser Thiere, 1841, p. 44, fig. 14). Erd/ asks if these variations of form are not coincident with an increasing or decreasing activity of the sexual organs (see Miller's Arch. 1842, p. 305). * point, they almost elude the highest and best micro- scopic powers. These barbels all point backwards when the lasso is extended, and serve, no doubt, as teeth, to prevent it from slipping on the objects over which it is thrown. But these most delicate struc- tures, which in beauty transcend that of all other tissues, can be. better appreciated by figures than by the most minute description; see Agassiz’s Memoir on Astrangia Danae (forthcoming in the ‘Smithsonian Contributions to Knowledge’’), Pl. VI. These observations, however, were made in 1848 ; see Proceed. Amer. Assoc. Advancem. Sc. 1848, p. 68. From my own observations there would, indeed, be nothing to add on the special points studied by Agassiz ; but a remark or two may be made as to the development of these forms. The lasso-vesicle is, originally, only an epithelial cell, of a spheroidal shape. It soon elongates, its contents become cloudy, after which, the coil is seen, very faintly marked, lying on the inner wall. It would seem probable, therefore, that its forma- tion was somewhat similar to that of the spiral vessels in plants, although it is true that the lasso- coils and these spiral vessels are analogous only in form and position, and not in structure. The details of the formation are unknown. These lasso-cells are more widely distributed among the Radiata than hitherto supposed. Agas- siz (as he has informed me by letter) has observed them on most of the Polypiand Acalephae, and even with some of the Mollusca, and although their general structure is the same, there are points of difference of even a zoological value. EpitTor. $$ 29, 30. THE POLYPI. 41 CHAPTER II. MUSCULAR SYSTEM AND ORGANS OF LOCOMOTION. § 29. The movements of Polyps are performed, partly by contractions of the sides of their body, in which are found no muscular fibres, and partly by a true muscular tissue. The fibres of this tissue have not regular trans- verse strize, although during their contractions there are sometimes, though rarely, seen irregular transverse bands.” § 30. In those Polyps having a true muscular system, this tissue is composed of interlaced fibres, forming a layer beneath the skin. A coarse net-work of this kind is seen in the arms of Hydra, although in the foot and rest of the body there is scarce anything comparable to muscular fibres.” Under the skin of Synhydra™ and in the arms of Elewtherza® this muscular system is much more apparent. A similar layer, very distinct, is observed in Actz- nia, which, in their mantle, is composed of both longitudinal and circular fibres, the contraction of which draws the tentacles together, and this, com- bined with that of the radiating fibres of the foot, gives rise to the various forms of these animals. The Bryozoa have the muscular system more apparent; in the cavity of their body completely isolated fasciculi are seen, composed of parallel fibres, serving especially for the withdrawal of these animals into their cells. These fasciculi arise from the internal surface of the body, and are inserted partly into the base of the tentacles, and partly into the neck and digest- ive canal, — thus serving almost exclusively as retractors of these last. 1 Milne Edwards, who declares he has seen striated muscular fibres in Eschara (Ann. d. Se. Nat. VI. 1836, p. 3), must have been deceived. I have been unable to perceive them in Eschara, Al- cyonella, Cristatella, and other species. Vord- mann also has not found them in Cellaria. (Ob- serv. sur la Faune Pontique, 1840, p. 679; also Miller's Arch. 1842, p. ccviii.) The irregular bands appearing during contraction, but afterwards disap- pearing, have been observed by Quatrefages with Edwardsia (Ann. d. Sc. Nat. XVIII. 1842, p. 84, pl. II. fig. 7, a-b).* 1 Corda, Nov. Act. Acad. C. L. C. Nat. Cur. XVIII. 1839, p. 299. Also Ann. d. Sc. Nat. VIII. 1837, p. 363. *[§29, note1.] Busk has described and figured the striated form of this tissue with Anguinaria spatulata and Notamia bursaria. (Trans. Micro- scop. Soc. of London, II.) Ihave been unable, however, after considerable search upon many Bry- ozoa, among which were several A/cyonella, to detect any appearances of this kind ; and I would venture a pretty confident pains that in the spe- 2 Quatrefages, Ann. d. Sc. Nat. XX. 1843, p. 238, pl. IX. fig. 3-5. 3 Quatrefages, Ibid. XVIII. 1842, p. 281, pl. VIII. fig. 3. 4 Bertho/d, Beitr. zur Anat. u. Physiol. 1831, p. 16 ; also in the body of Edwardsia, Quatrefages has found longitudinal and circular fibres (Ann. d. Sc. Nat. XVIII. p. 84). 5 Similar muscles have been observed by Farre (Phil. Trans. 1837, p. 387) in Bowerbankia, Vesi- cularia, Lagenella and other Bryozoa. Miine Edwards has seen them in T'ubulipora and Es- chara. (Ann. d. Sc. Nat. VIII. 1837, p. 324; VI. 1836, p. 23, pl. I. fig. 1,c,1,d; pl. II. fig. 1, a.) Coste has given a very detailed description of the cies examined no such form of muscle is present. Quite lately, however, the subject has been care- fully examined by Al/man (Rep. Brit. Assoc. 1850, p. 318), and his descriptions are such as to leaye no doubt upon the existence of the striated fibre with the species he has examined, among which are the Paludicellae.— Ep. 42 THE POLYPI. $$ 31, 32. With Eschara there are, moreover, two fasciculi in each cell, which move its operculum, and thus close the entrance of this cavity. ° g 31. Locomotion is performed by the Polyps in various ways. With the Hydrae, by their long-stretching arms; with Actiniae, by the contractions of the disc of their foot ; ? while the Edwardsiae, having elon- gated bodies which are not attached by a foot, progress by vermiform movements.” With Cristatella mirabilis, the whole colony moves itself along by the foot-like basis, like the Actiniae. Some Polyps, at a certain period of their development, move frecly in the water by discoid contractions of their body, like the pulmograde Acalephae.® § A very remarkable peculiarity is the presence, in certain Bryozoa, of organs shaped like a bird’s head, and which swing to and fro at the base of their cells. In some species, hese organs have the form of lobster’s claws, being composed of both a fixed and a movable piece. This last is corneous, anid moved by a muscle which arises from a cavity in the first. It is not yet known by what means either this beak is opened, or the whole organ moves to and fro. Equally unknown is the function of these singular organs, the move- ments of which persist after the death of the animal, and of which, there-. fore, they are independent.© They are perhaps organs of defence or pre- hension, and analogous to the Pedicellaria of the Kchinoderms. muscles of P/umatella (Comp. rend. XII. 1841, p. 724; Miiller’s Arch. 1842, p. ccx).* 6 Milne Edwards, Aun. d. Sc. Nat. loc. cit. p. 24, pl. I. fig. 1, e. 1 Berthold, loc. cit. p. 14. 2 Quatrefages, Ann. d. Sc. Nat. XVIII. p. 74; also Forbes, Ann. of Nat. Hist. VIII. 1842, p. 243. 3 I have been able to confirm the observation of Dalyell (Froriep’s Notizen 1834, No. 920, p. 276) upon this motion in Cristatella. Trembley, also, has observed that the corallum of Plumatella cristata moved half an inch in eight days (see his Mémoire pour seryir a l’Hist. des Polypes d’eau douce, 1775, p. 298). 4 See the observations of Steenstrup (Ueber ad. Generationswechsel, 1842, p. 20) upon Coryne fri- tillaria ; also those of Van Beneden (Mém. sur les Campanulaires, 1843, p. 29, or Froriep’s neue Noti- zen, 1844, No. 663, p. 38) upon Campanularia ge- latinosa. *|§ 30, note 5.) Al/man (Report Brit. Assoc. 1850, p. 8314) has described a very complete mus- cular system in the fresh-water Bryozoa. Inthe spccies with bilateral lophophores, there are seven distinct sets: 1. Retractor muscles of the polypide; 2. The rotatory muscles of the crown; 3. The tentacular muscles ; 4. The elevator muscle of the valve ; 5. Superior parieto-vaginal muscles; 6. Inferior parieto-vaginal muscles ; 7. Vaginal sphinc- ter. The walls of the stomach also contain circular muscular fibres. 1 These organs were first described by Ellis (Essai sur Hist. Nat. des Corall. 1756, p. 51, pl. XX, fig. A). Nordmann (Observ. sur la Faune Pontique, 1840, p. 679, pl. ILI. fig. 4) has described and figured them with much accuracy. In Ce/- laria avicularis, Bicellaria ciliata and Flustra avicularis, they are formed like lobster’s claws. In Retepora cellulosa they are pincer-like, and in Telegraphina they are articulated stings. See also Krohn in Froriep’s Notizen, 1844, No. 533, p- 70. ’ For the organs having the form of a bird’s head and a lash, and which are present in certain Bry- ozoa, see also Van Beneden, Recherch. sur Panat. &c., des Bryozoaires, in the Nouv. Mém. de Brux- elles, XVIII. 1845, p. 14, pl 11. III., and Reid in the Ann. of Nat. Hist. XVI. 1845, p. 385, pl. XII. 2 Darwin’s Voyage of the Beagle, 1844, pt. I. p. 262. With Paludicella, the muscular system is some- what different ; there are here five sets, — the Ist. 5th, 6th, and 7th of the preceding, and the parie- tal muscles. But with the Ist there is here only a single instead of a double fasciculus. — Ep. t [§ 32, note 2.] See Hincks (Ann. Nat. Hist. VIII. 1851, p. 353), who regards these avicularia as organs of defence, and has observed them seiz- ing and retaining foreign bodies. — Ep. $$ 33, 34. THE POLYPI. 43 CHAPTERS III. AND IV. NERVOUS SYSTEM AND ORGANS OF SENSE. § 33. As yet only a very rudimentary and imperfectly distinguished nervous system has been made out in the Polyps; this consists of round masses, which are regarded as composed of nervous matter (ganglia), situated in the parenchyma. A ganglion of this kind has been supposed to have been observed about the mouth.” § 34. Investigations upon their organs of sense have not been more suc- cessful. However, the sense of touch appears developed over the whole surface of the body, but specially so in the extremely irritable arms and tentacles. But, as yet, no tactile nerves have been found in these parts. In the same manner, light, to which these animals show a greater or less sensibility, is perceived rather by the general surface of the body than by special organs. There are, however, in some species, at particular stages of development, during which they swim freely about, certain nicely-defined bodies situated upon the sides of the body, and which may be regarded as special organs of light and sound. This is the case with Syncoryne ; and Coryne® has in their place four red organs which correspond exactly to those found on the border of the dise of the pulmograde Acalephze, and which have been re- garded as organs of sense. The organ seen at the base of the six arms of Eleutheria dichotoma fo) has quite the appearance of an eye ; 1A double esophageal ganglion has been ob- served by Dumortier (Mém. sur ? Anat. et la Physiol. d. Polypiers composés d’eau douce 1836, p.41, pl. IL. fig. 2) in Lophopus cristallinus (Plu- matella cristata of Lamarck); and by Coste (Comp. rend. XII. 1841, p. 724)in the Plumatellae in general. Nordmann also has seen a similar ganglion under the mouth of Plwmatella campa- nuiata (Lamarck) (loc cit. p. 709), and of Tendra zostericola (Ann. d. Sc. Nat. XI. 1838, p. 190). According to Van Beneden, a nervous ring sur- rounds the cesophagus of Alcyonella (Ann. d. Sc. *[§ 33, note 1.] Aliman has observed with Cristatella mucedo asmall roundish body situated at the upper end of the pharynx, and which he re- gards asa nervous ganglion (Rep. Brit. Assoc. Ad- vancem. of &c. 1846, p. 88). This observation he subsequently confirmed, and has observed with Plumatella repens this ganglion ( which he terms the great cesophageal ganglion) send off a large filament to each of the tentaculiferous lobes ; also a smaller one passing off at each side to embrace the cesophagus, while a very short one was distrib- that is, there can be distinguished in Nat. XIV. 1840, p. 222). Coste asserts the presence of a nervous system in Pennatula (Froriep’s neue Notizen, 1842, No. 450, p. 154). That which Spix pretended to have discovered in the foot of Acti- nia (Ann. d. Mus. d’Hist. Nat. 1809, p. 443, pl. XXXIII. fig. 4) has been properly rejected by most modern zootomists, as an illusion. See Ber- thold, loc. cit. p. 6.* 1 Lovén, Wiegmann’s Arch. 1837, I. p. 323. 2 Steenstrup, Ueber den Generationswechsel, p. uted in the substance of this last organ. And, finally, another set of filaments were distributed to the organs about the mouth. See Report of the same, for 1849, p. 72. According to a late Report, this observer appears to have been able to make out a distinct nervous system in all the fresh-wa- ter Bryozoa, except Paludicella. He has, how- ever, been able to detect no certain organ of spe- cial sense. See report of the same for 1850, p. 319.— Ep. 44 THE POLYPI. $$ 35, 36. it a cornea, a crystalline lensand a red pigment layer surrounding the whole.“ Furthermore, there are upon the border of the disc of the campanulate Campanularia, colorless corpuscles, containing a calcareous nucleus, which is transparent as a crystal and soluble in acid. These organs should probably be regarded as the most simple form of the auditory organs, for they have only a simple vestibule with its single otolite. CHAPTER V. DIGESTIVE APPARATUS. § 35. The digestive apparatus of Polyps is formed after two different types. With the Anthozoa it consists of a mouth and a simple stomachal sac with- out an anus. But with the Bryozoa, there is a mouth and anus, and a digestive canal which may be divided into the sections of csophagus, stomach, small intestine and rectum. § 36. The mouth of Polyps is usually surrounded by a circle of long, very contractile tentacles or arms. These tentacles are tubular, and connect with the cavity of the body.” They are simple,” or pennate,® and may be dis- posed around the mouth in a single or a multiple® circle ; they are also frequently covered with cilia. Thus, the cylindrical tentacles of Actinia are entirely covered by ciliated epithelium. With the Bryozoa, on the contrary, the slightly-flattened ten- 3 Quatrefages, Ann. a. Sc. Nat. XVIII. 1842, p. 280, pl. VIII. fig. 1, d, d, and fig. 6. 4 See Krohn (Miiller’s Arch. 1843, p. 176) and Kélliker (Froriep’s neue Notizen, 1843, No. 534, p. 81). Van Beneden has perceived in the campa- nulate and free individuals of Campanularia ge- latinosa and geniculata, not only eight marginal bodies, each containing a calcareous nucleus, but also four nervous ganglia about the base of the stomach (Mém. sur les Campanulaires de la céte d’Ostende, 1848, p. 24-27, pl. If. III.). I am yet undetermined upon the question whether, as Van Beneden thinks, these bodies have sometimes the function of organs of vision, and sometimes that of organs of hearing. I am also in doubt as to the opinion of Huschke (Lehre von den Eingeweiden und Sinnesorganen, 1844, p. 880), who regards as otolites the calcareous bodies which have been ob- served in the peduncle of Veretillum cynomo- rium. Nordmann (Versuch. einer Monogr. des Tergipes, p. 88) has described as auditory organs the marginal bodies of the free-swimming Campa- nulariae. 1 This cavity which is in the arms of most Polyps *(§ 36, note 1.) Subsequent researches have shown that the cavity of the tentacles does open externally through a small papilla. See Dana, does not open outwards at the extremity of these organs. I doubt, in fact, if the Actinina are an ex- ception to this. It therefore appears singular that Rymer Jones (A General Outline of the Animal King. p. 41, fig. 13), and Lesson (Duperrey, Voy- age autour du Monde. Zoophytes, p. 82, No. 1, fig. 1), expressly mention and distinctly figure these openings ; the first with an Actinia, the second with an Eumenides. According to Van Beneden (loc. cit. p. 15) the tentacles of Campanularia are without these cavities. Butthis is contradict- ed by Lovén (Wiegmann’s Arch. 1837, Bd. 1, p. 252). In Hydra the cavities open distinctly into the stomach, asis probably the case with many other Hydrina. Frey and Leuckart likewise doubt the constant presence of an orifice at the apex of the tentacles of the Actiniae.* 2 Actinia, Hydra, Flustra and Campanularia. 3 Veretillum, Lobularia, Isis, Gorgonia, and Zoanthus. 4 Hydra, Flustra, Zoanthus and Veretillum. 5 Actinia and Caryophyliia. 6 Veretillum, Flustra, Eschara, Cristatella and T'ubulipora. Structure and Classification of Zoophytes. Phil. 1846, p. 32.— Ep. § 87. 45 tacles have only a single row of cilia, which move regularly and volunta- rily, like the rotatory organs of the Rotatoria. By means of the currents produced by the cilia of their tentacles, many Polyps draw towards their mouth light particles of food; others make use of their ciliated arms to seize larger portions.© This act is aided by the nettling and various prehensile organs, which are more usually found upon those Polyp-arms having no cilia. These organs are found upon the tentacles of Actinia, Edwardsia, Veretillum and Alcyonium, and without doubt serve for the seizing of the prey as well as its retention until death, But these should not be confounded with special prehensile organs found on the tentacles of certain species. These consist of a small coriaceous capsule, from which the animal can project a kind of sting.“” By means of these organs, the animal can attach itself like a bur to external objects, and not by suction, as is generally supposed. The circular or oval mouth is always situated in the centre of the an- terior extremity of the body; it is often surrounded by a lip formed of circular fibres.” In a few species, the mouth projects like a cone at the base of the tentacles.°? With the Plwmatellae™ the mouth is topped by a tonguelet covered with rapidly moving cilia. Some of the Anthozoa, which capture animals of considerable size, can, in swallowing them, dilate their mouth to an astonishing width.“ . THE POLYPI. DIGESTIVE CAVITY OF ANTHOZOA. § 37. The simple stomach of Anthozoa, which is of a variable length, opens in general directly external by means of the mouth,” and with a few species, only, is there a muscular cesophagus. With some, the stomach blends with the walls of the body, but usually it is more or less isolated. There remains, therefore, a cavity of the body of variable size, and which is directly continuous with the cavities of the arms. In those Polyps living in colonies, it is prolonged into canals trav- ersing the corallum, and in this way the cavities of the bodies of all the 7 Flustra, Eschara, Tubulipora and Crista- tella. 8 Actinina. 9 Hydra, Coryne, Eleutheria, Sertularia, Cam- panularia and Alcyonium. 10 Such prehensile organs have been observed by Quatrefages upon the clavate tentacles of Eleu- theria. We thinks also he has observed two mus- cles in their capsules, by which the retractile sting is projected (Ann. d. Sc. Nat. XVIII. 1842, p. 276 and 283, pl. VIII.; or Froriep’s neue Notizen, 1843, No. 543, p. 230). The oval vesicles which roughen the tentacles of Campanularia, and which Loven (Wiegmann’s Arch. 1837, IL. p. 252) has de- scribed as small spinous warts, are probably of the same nature. In Hydra each hook-organ upon the arm is surrounded by a group of similar vesicles, in the interior of which is a rigid bristle. ‘These or- gans are here found only upon the arms. They are distinguished from the organs having hooks by their less size, and from their having no project- ing filament. Corda has not properly distin- guished them from the hook-organs, whose fila- ment is still unprojected (see his Memoir in the Noy. Act. physico-medica. XVIII. p. 300, Tab. XV. fig. 5, 9, 10). Perhaps the organs which Erdl (Miller's Aych. 1841, p. 424, Taf. XV. fig. 8) has seen upon the tactile lobules of Veretillum cyno- morium are of this kind. Ul Actinia and Edwardsia. 12 Hydra, Coryne and Campanularia. 13 Alcyonella and Cristatella. 14 Actinia and Hydra. 1 Veretillum, Alcyonium, Actinia and Hydra. 2 Edwardsia. See Quatrefages (Ann. d. Sc. Nat. XVIII. pl. I. fig. 25 pl. II. fig. 1, 2). 3 Hydra. The stomach of the arm-polyps is not, as has been formerly supposed, a simple excavation in the body. It has proper walls distinct from those of the body, by which, however, they are closely embraced. There is, therefore, in Hydra no cavity of the body, and the cavities of the ten- tacles open directly into the stomach. ‘This is also true of E/eutheria (Quatrefages, Ann. d. Sc. Nat. XVIII. p. 283). 46 THE POLYPI. § 87. Polyps are placed in direct intercommunication. It is not rare to find this general cavity divided into chambers by mesenteric membranes stretch- ~ ing longitudinally from it to the external surface of the stomach.” The base of the stomach of many, and perhaps all of the Anthozoa, is pierced by one or more valvular openings, which communicate with the cavity of the body.® These animals, by controlling at will these orifices, can allow to pass into the cavity of the body the proper materials, which are probably water and liquid chyle.® This digestive apparatus thus com- municating with the cavity of the body, reminds one of the organization of the Infusoria.” The cavity of the stomach is lined by very delicate ciliated epithelium, which is continuous throu gh the orifices upon every surface of the cavity of the body and arms, and even into the intercommunicating canals of the corallum. The color of the walls of the stomach is quite varied, and is due to cer- tain :pigment cells which very probably perform the function of a liver ; for these animals are entirely wanting in any other glandular appendix of the alimentary canal, analogous to a liver. 4 There are often eight of these longitudinal chambers, as in Veretillum, Alcyonium and Al- cyonidium (see Icones zoot. Tab. XXXIV. fig. 25 also Ann. d. Sc. Nat. [V. 1835, pl. XVI. fig. 3, and pl. XII. fig. 3, 4). In Actinia there are seven more. With Edwardsia the eighth mesenteric di- visions do not reach the sides of the body (Qua- trefages loc. cit. pl. I. fig. 2).* > These orifices were long ago observed by the elder anatomists upon various Polyps. After- wards their existence was incorrectly doubted by other naturalists ; for lately they have been dis- tinctly made out. Thus, in Veretillum cynomo- rium (Rapp, Nov. Act. physico-medica X1V. 1829, p- 650), in Alcyonidium and Alcyonium (Milne Edwards, Aun. d. Sc. Nat. IV. p. 325, pl. XV. fig. 6), and in Edwardsia (Quatrefages Ann. d. Sc. Nat. XVIII. p. 91). In Sertularia and Campanularia there are openings between the stomach and the tubulous cavities of the corallum (Lister, Phil. Trans. 1834, p. 371, and Van Beneden, Mém. sur les Campanu- laires, loc. cit. p. 17). There must be direct com- munication of this kind with the Actiniae, since they regularly reject by their mouth nettling fila- ments, from the chambers of their body. With Hydra, the stomach communicates, by an orifice situated at its base, with the narrow tubulous cavity of its cylindrical foot. But at the extremity of this tube there is no oval opening, and the tube itself can- not be regarded as a rectum, for it receives neither feeces, nor fragments of food, and is not affected by the frequent enormous dilatations of these animals from surfeit. Corda therefore is incorrect in as- signing an anus to these animals. (Nov. Act. phys- ico-medica XVIII. p. 302, Tab. XIV. fig. 2, E.) He appears to have entirely neglected the foot of this animal, which, however, has been well figured by Ehrenberg (Abhandl. d. Berl. Akad. 1836, p. 154, Taf. IL. fig. 1); and since Roesel (Insektenbel. IIT. Taf. LXXVILL. and LXXIX. fig. 2, and LXXXVI. LXXXVILI. fig. 6) has perceived it in all unmuti- lated arm-polyps. Sars (Faun. littoral. Norveg, p. *[§ 37, note 4.] With all the Actinaria the lam- ellz of the visceral cavity are the multiples of six ; all the Alcyonaria have eight of these lamellz. See Dana loc. cit. p. 49. — Ep. {[§ 37, note 5.] With the Actinoidea, recent researches have shown that the stomach communi- 21) has found with a Lucernaria a stomach opening inferiorly, and communicating directly with the cavity of the body. This communication has been observed also by Frey and Leuckart (Beitr. p. 3) with the Actiniae and several other Anthozoa.t 6 Quatrefages (Ann. d. Sc. Nat. XVIII. p. 87, 91) has seen the stomach of Edwardsia entirely filled with Spirorbis, and other solid food, without any of it passing into the cavity of the body. 7 With Infusoria, the lower end of the cesophagus is free, so that the food passes directly from it into the parenchyma of the body, where it forms a cay- ity ; but with the Anthozoa, there is a stomach, from which chyle alone can pass into the cavity of the body. 8 These cells are white in Edwardsia, yellow in Alcyonidium and Alcyonium, and brown in Vere- tillum and Hydra. In the last, the brown is dis- tinctly due to irregular pigment granules of that color, floating in the clear liquid of the cell. Prob- ably these cells, by bursting, empty their contents into the stomach ; at least, I have been able to find no excretory duct, such as Corda has figured with the Hydra fusca (Noy. Act. Acad. physico-medica XVIII. p. 302, Tab. XV. fig. 15—17; or Ann. d. Sc. Nat. VIII. p. 366, pl. XIX. fig. 15—17). In Hydra viridis, these brown cells of the stom- ach can easily be distinguished from the layer of green pigment belonging to the parenchyma of the body. Moreover, if a transverse section of this animal is made, there appears a wide difference of organization between the internal and external sur- face of the stomach; the first has ciliated epithe- lium and hepatic cells, the second a bare skin with prehensile organs. This being so, how can these animals be everted like the finger of a glove, as some naturalists have affirmed, and yet live ? for the two surfaces of the stomach, so different, could not re- place each other, and then again the cavities of the arms would open directly outward. Indeed, it is not possible to return unmutilated an everted Polyp, since the inextensible cavity of its foot can- not leave the body with impunity. The gastric cates with the cavity of the body by a single ori- fice only, which may be closed by muscles. See Dana, loc. cit. p. 40, 44, pl. XXX. fig. 3, a, b, ¢, d. It has been since verified by Cobbold, Ann. Nat. Hist, XI. 1853, p. 121, with figures. — Ep. $$ 38, 39. THE POLYPI. 4T DIGESTIVE CAVITY OF BRYOZOA. § 38. The very complicated digestive canal of the Bryozoa floats freely in the spacious cavity of their body. It is composed of an cesophagus which, at its lower extremity, dilates into a round or oval muscular crop ;“” upon this immediately succeeds a ccecal stomach, from the upper portion of which a small intestine arises and passes upwards in front. This, after a course of variable length, ends by a constriction in a short but large rectum, which opens in the vicinity of the mouth, at the external side of the base of the tentacles.” The digestive canal here, therefore, is not in communication with the cavity of the body. Its whole inner surface is lined with very active, ciliated epithelium, which keeps its contents in motion, and especially the feces of the rectum. The sides of the stomach are often colored brown, yellow or green, from the presence of hepatic cells.t CHAPTERS VI. AND VII. CIRCULATORY AND RESPIRATORY § 39. A vascular system has yet been found only with a few Polyps; but there it is so apparent that its presence in others may be inferred. The blood- vessels exist upon both the sides of the body and of the stomach, and are in part longitudinal, in part circular, ending in a capillary net-work. They are not simple canals excavated in the parenchyma, but have proper walls, SYSTEMS. and circulate a liquid containing a great number of white (blood) globules.” juice of the Anthozoa must have a very great digestive power, since the Actinia eat hard-shelled crustacea, and even the soft Hydrae quickly dis- solve the larve of Nats and Chironomus. But the indigestible parts of these animals, such as epi- dermis, bristles, hooks and jaws, are afterwards ejected by the mouth. lin Bowerbankia (Farre, Phil. Trans. 1837, p. 392, Pl. XX. fig. 5; Pl. XXI. fig. 7) this crop is composed of pyramidal corpuscles, with the apices pointing inward, so as to act like teeth. I have observed avery similar structure in Alcyo- nella stagnorum. 2In Bowerbankia and Vesicularia the small intestine is very long (Farre. loc. cit. Pl. XX. and XXII). I have observed it very short with Cris- tatella mirabilis.* * [§ 38, note 2.] According to 4/lman (Report Brit. Assoc. 1850, p. 310), the cesophagus succeeds the stomach without the intervention of any dis- tinct crop with all the fresh-water Bryozoa. The stomach is large and thick-walled, and may be divided into a cardiac and a pyloric portion. The pylorus is distinctly valvular, and the intestine, 1 Milne Edwards has perceived a vascular net- work of this kind in the sides of the body, with Alcyonidium elegans, and Alcyonium palma- tum and stellatum (Ann. d. Sc. Nat. IV. p. 338). Quite recently, Will has described the vas- cular system of Alcyonium palmatum (Froriep’s neue Notizen, 1843, No. 599, p. 68). According to him, white vessels may be perceived, even with the naked eye, upon the longitudinal furrows of this animal. These enter the lobules on the border of the body, and there form a dense net-work, from which a branch is sent to each arm, and this last gives off laterally a twig to each tactile lobule. The principal trunk of the longitudinal vessels con- tinues upon the sides of the stomach to the base of the tentacles. At the point where the bodies of the Polyps continue with the corallum, there are wide at first, passes along the side of the cardiac cavity and cesophagus, and rapidly decreases in diameter, until it terminates in a distinct anus just below the mouth. — Ep. t [Note at end of § 38.] See in this connection my note under § 13, note 2.— Eb. 48 “THE POLYPI. $$ 40, 41. § 40. All Anthozoa and Bryozoa have a proper circulation; for there rises and falls in the cavity of their body a liquid, which is usually clear, and often contains round and colorless corpuscles: This rises even to the end of the cavity of the tentacles, and then returns into that of the body generally. In the colonial Polyps, these currents, by traversing the canals of the corallum, thereby pass from one animal to another. This movement is caused by ciliated epithelium, which, as we have just seen, lines all the cavities of these animals. With the Bryozoa, the cavity of whose stomach does not communicate with that of the body, these currents are continuous. regular, and have a definite direction. But with the Anthozoa they are changed by the reciprocal action through the stomachic orifices of the liquids of the stomach and cavity of the body. These currents are perceived in the arms, even when the cavities of these organs open directly into the stomach. § 41. Nothing can yet be positively said as to the nature of this circulating liquid. for it is still doubtful whether this whole phenomenon should be regarded as an aqueous ora sanguineous circulation. If we refer to the fact that the Anthozoa can introduce water into the system through the apertures of the stomach, it should be admitted that this system has an aqueous character, performing, perhaps, the function of an internal respiratory apparatus, given off from the eight principal longitudinal vessels numerous lateral branches, which anasto- mose frequently in the canals of the corallum, and finally form a capillary net-work. The white, semi-transparent corpuscles contained in thin blood have, according to Will, a diameter of about 1-1200 of an inch, and out of the vessels have a globular aspect. According to this same observer, there is a similar vascular system in Actinia.* 1 The circulation in question has been observed by many investigators. Trembley (Mém. pour servir a lHistoire des Polyps, p. 219) has per- ceived it in Plumatella cristata. Dumortier (Mém. sur l’Anat. et la Physiol. des Polypes, p. 47) has confirmed this observation. Cavolini (see his Memoir on the Anthozoa, p. 56, 87) has seen it in the tubes of several Sertularina. There are various opinions as to the cause of these currents. Gruzt- Auisen (Isis. 1828, p. 506) studied them in the arms of Hydra, and regarded them due to a com- munication with a circular vessel surrounding the mouth. But, according to the observations of Meyen (Brown’s Miscellaneous Botanical writings, IV. p. 490), of Ehrenberg (Mittheil. aus. d. Ver- handl. d. Gesellsch. naturf. Freunde z. Berlin, 1836, p. 27) and myself, the cavities of the arms open directly into the stomach. The movements of the liquid in the arms of Hydra are due not only to the general contractions of the body, as Gruithuisen and Meyen have supposed, but also to the cilia covering these parts. This * [§39, note 1.] Subsequent researcheshave failed to detect any true circulatory system with the real Polyps, and there now can be but little doubt that no such system exists. As with the Acalephs, was first pointed out by Grant (The new Edinb. Phil. Jour. 1827, p. 107 5 or Outl. of Comp. Anat. 1841, p. 480), who observed these currents in Flustra, Lobularia, Virgularia and Pennatula. Nordmann, who has examined this circulation in the body and tentacles of Alcyonella diaphana, and Plumatella campanulata, and other Bryozoa, did not find any cilia. He compared the currents to those seen in the joints of Chara (Microg. Beitrag II. p. 75, or Obser. sur la Faune Pontique, p. 709). I feel positive about the presence of cilia in the body of Cristatella mirabilis and Alcyo- nella stagnorum. Lister has carefully described this circulation with T'wbudaria, Sertularia and Campanularia; and finding no adequate cause, has likened it to that of Chara (Phil. Trans. 1834, p. 866, et seq.). Ehrenberg (Abhandl. d. Berl. Akad. 1832, p. 299) and Lovén (Wiegmann’s Arch. 1837, I. p. 254) attribute these currents in Sertularia and Campanularia to a peristaltic movement of the canals of the body ; which, how- ever, Van Beneden (Mém. sur les Campan. loc. cit. p. 18) has been unable to see in these Polyps. Erdl (Miller’s Arch. 1841, p. 426) attributes it, in Veretillum cynomorium, to cilia; and Will (Froriep’s neue Notizen, 1843, No. 599, p. 69) has found all the cavities of the body and corallum of Alcyonium palmatum lined with cilia. It is, moreover, certain that the currents observed by Erdl (Miiller’s Arch. 1841, p. 428) and Dumor- tier (Mem. loc. cit. p. 52) in the tentacles of Actinia are due to ciliary action. their nutritive and digestive systems are combined; and, as with them also, the circulating, nutritive liquid is chyme. See also Dana loc. cit. p. 35. — Eb. § 41. THE POLYPI. 49 while the tentacles, in the cavities of which are regular currents, serve ag external organs of respiration, similar to branchiae. But, if we regard the whole as a true circulation, the contained liquid with its corpuscles will be analogous to blood. But this view is opposed by the fact that, with Alcyontwm, with Actinia, and perhaps many other Polyps, there is a true vascular sanguineous system.” We ought, therefore, to compare the liquid in question to chyle, which passes from the stomach to the general cavity of the body, in the Bryozoa by exosmose, but in the Anthozoa by the orifices of the stomach.” The opinion that these currents form a vascular system, moreover, is not reconcilable with the fact that the Anthozoa can at will empty the contents of their stomach into it, or in the same way shut off from it the water. We are obliged, then, to regard all these cavities as constituting a vascular aqueous system, performing a respiratory function, by which, in the Anthozoa, all the internal parts are constantly bathed with fresh water. This renewal of water is effected by its alternate ingress and egress through the stomach,® during which chyle-corpuscles could easily, by being mixed with water, be carried into this aqueous system. With the Bryozoa, where this system is, without doubt, equally one of respiration, we shall have to seek for the openings by which this renewal of water takes place. These are situated near the anus, and place the cavity of the body in direct communication with the external water.* 1 See § 39, note 1. 2 Ehrenberg and Loven regard the canals of the corallum of Campanularia and Sertularia as direct prolongations of the stomach, and desiguate them as intestinal tubes, and their contents as chyme. 8 This alternate ingestion and egestion of water has been positively observed by Lister, Loven and Van Beneden, in Sertularia and Tubularia. 4 By an opening of this kind, Meyen (Isis 1828, p. 1228) saw escape the eggs of Alcyonella stag- nalis, which were free in the cavity of the body. Van Beneden (Ann. d. Sc. Nat. XIV. 1840, p. 222) declares that he has observed at the base of the tentacles of Alcyonella a series of orifices, * [End of § 41.] In this connection should be mentioned branchia-like organs, described by Dana (loc. cit. p. 42) with the Zoanthina. A pair of them is attached to each of the larger lamelle. He remarks, ** The structure of these organs is such that we can hardly doubt their branchial nature ; yet no circulating fluid was detected within them.” I find no other mention of these parts, except by Lesueur (Jour. Acad. Nat. Sc. Philad. I. 183-185, Pl. VIII. fig. 1, 5, 9), who regarded them as of an hepatic nature. — Ep. t |§ 41, note 4.] The true nature and relations of the respiratory and circulatory systems of the Bryozoa are yet imperfectly understood. There can be but little doubt that water is by some means introduced into the general cavity of the body, and there mingles with the nutritive fluid, which trans- 5 which may be called aquiferous mouths, for by them the water enters the cavity of the body. This is perhaps the case with Actinia, also; for Rapp (Ueb. die Polypen u. die Aktinien, loc. cit. p. 47) has here found numerous small orifices scattered over the whole surface of the body, and through which are emitted jets of water when the animal is squeezed, thus showing that they belong to an aquiferous system. It is quite improbable that the hollow tentacles of Actinia are open by an orifice at their apex for the circulation of water, as many naturalists have supposed. Quatre- Jages (Ann. d. Sc. Nat. XVIIL. p. 96) is quite opposed to this opinion. See also above § 36, note 1.} udes through the walls of the alimentary canal. But the apertures for the introduction of this water have not yet been clearly seen. It is true that Van Beneden thinks he has found ‘‘ Bouches aqui- féres,” as above mentioned, but their existence there has not been fully verified, and is even denied by Allman. At present, therefore, it cannot be said that the Bryozoa have a true aquiferous system, like the Anthozoa. The perigastric fluid is, separated from the water, most probably the elaborated product of digestion, and the corpuscles therein contained chyle-corpuscles. Al/man’s view, therefore (Report Brit. Assoc. 1850, p. 319), appears the most correct: ‘‘ The perigastric circu- lation, therefore, unites in itself the triple function of a chyliferous, sanguiniferous and respiratory system.” — Ep. 50 THE POLYPI. $$ 42, 48. CHAPTER VIII. ORGANS OF SECRETION. § 42. Nothing like urinary organs have yet been found in Polyps. Perhaps the borders of the mantles of the cellular Polyps should be regarded as organs of special secretion, since by them the increase and production of these cells take place. CHAPTER IX. ORGANS OF GENERATION. 43 § 43. Polyps reproduce by gemmation, fissuration, and by eggs. 1. Fissuration is comparatively rare; it takes place nearly always lon- gitudinally, and the division may or may not be complete.” 2. Gemmation is their most common mode of reproduction. The new individuals may be completely detached, or may remain connected with: the parent corallum. a: In gemmation, complete separation of the young individual is, on the whole, rare. It is best known in Hydra, with which the buds always appear upon a certain part of the body, — that is, at its union with the foot.” A bud of this kind consists always of a simple fold of the wall of the stomach and the skin, so that the stomach of the young individual is in direct communication with that of the parent, and the chyme can pass freely from one to the other. When the foot of thisnew being has acquired a proper development, it is completely detached at its inferior extrem- iby. 5 : Gemmation without separation of the new beings is quite common with Polyps, and occurs with very various modifications. The buds are formed sometimes upon the sides, sometimes upon the base of the body. In the first case, the coralla have a dendroid aspect; in the second, they are more lamelliform, spherical or lapidescent. These variations are not limited to certain genera or species, being often due to external influences, 1 The calcareous tubes of Tubipora, and the corneous ones of the Sertularina and other Bryozoa, are, without doubt, secreted by the border of the mantle, as is true of the shells of mollusks. 1 According to Roese/ (Insektenbelust. III. p. 504, 523. Taf. LXX XIII. fig. 3), fissuration takes place transversely with Hydra. Longitudinal fissuration is principally observed with the Madre- porina. When it is complete the cells of the coral- lum are definitely limited, as in Astraea, Favia, and Caryophyllia ; but, when incomplete, the cells are branched, lobulated, and of irregular contour, as in Agaricia, Maeandrina, and Monticularia, &e. 2. Roesel (loc. cit. III. Taf. LXXXYV. fig. 2, 3, 5, Taf. LXXXVI. and LXXXVIILI. fig. g. h. and Taf. LXXXIX. fig. 4). The exceptions to this rule, which are sometimes observed, are probably due to lesions of an accidental nature. $$ 44, 45. THE POLYPI. 51 and especially the nature of the soil upon which the colony may have been fixed.* ® § 44. 3. It is probable that all Polyps reproduce by eggs. This requires two kinds of organs, one to produce the egg, the other the semen. Both kinds, ovary and testicle, have already been described in many species. Their distribution is quite varied. In some, the sexes are united in the same individual,” in others they are distinct ;© with the colonial polyps the sexes are separate, and each colony® may be composed of individuals which are androgynous, or those of one sex alone. Some species are sexless, and remain so ; but they produce by gemmation individuals of a particular character, which have sexual organs.© These last, which have usually either a campanulate or discoid form, are separated from the corallum often before the sexual organs have been formed, and which they do not acquire until an advanced period of their lives. Durin this time they swim freely about, like the pulmograde Acalephae,® for which, as well as for young Polyps, they are often taken. § 45. That the relations just described really exist, may be learned from the following facts: In Coryne echinataand vulgaris, there are formed at their base, quadrangular and campanulate individuals,: which lay numerous eggs.” In like manner also, ovigerous capsules are formed about the base ot Syncoryne ramosa.” In Coryne fritillaria,® the new individuals are completely detached and swim freely about. closely resembling Medusae. In this condition they are developed, and their eggs come to maturity. 8 Eschara and Flustra have a lamellated form when fixed to stones, shells, or the broad leaves of Algae; but are tubular when attached to the stems of plants. Alcyonella stagnorum under- goes similar changes in the form of its corallum. It divides in a regular dichotomous manner (Lichhorn, Beitr. zur Naturgesch. d. kleinsten Thiere. Tat. 1V.; also Roesed, loc. cit. Taf. LX XIII. and LX XIV.), andin this form has been described under the name of Plumatella campanulata by Lamarck. But when a colony of these Polyps is fixed upon a stone or a sunken root, they com- mence to be developed in a dichotomous manner. But afterwards they become lapidescent by the branches of both modes interlacing each other. As the mass becomes more voluminous and dense, the tubes of the dead generation support those of the living. (See. Lamourouax, Exposit. méthod. des Genres de ordre des Polypiers, Pl. LXXVI. fig. 5.) Under this form this Polyp has received the name of Alcyonel/la stagnorum (see Raspail, Hist. Nat. de )’Alcyonelle fluviatile).¢ 1 Hydra. 2 Actinia. t 8 Alcyonella. * [End of § 43.] For a full account of the reproductive process with Polyps, and the most philosophical exposition of the relations of gem- mation and its analogies and affinities with other developmental processes, see Dana, loc. cit. p. 35. No abstract can be given of such a work. — Ep. t [§ 45, note 3., For full details of the gemmi- parous mode of reproduction with the Bryozoa, see Van Beneden (Recherch. sur lorganis. des 4 According to Erdl (Froriep’s neue Notizen, 1839, No. 249, p. 101) the coralla of Veretilium cynomorium and Aleyonium have always either male or female individuals alone. Kvohn has perceived the same of Sertularia (Miller’s Axch. 1843, p. 181). 5 Coryne, Syncoryne and Campanularia. 6 Coryne and Campanularia. 7 Very striking, at least, is the resemblance of Van Beneden’s (Mém. loc. cit. pl. IL.) figure of a free female of Campanularia gelatinosa and those of Sars (Beskrivelser. loc. cit. p. 28, Taf. VI. fig. 14) of small Acalephae, named by him Cytaeis octopunctata, and by Will (Horae tergestinae, 1844, p. 68, Taf. II. fig. 5) as Cytaeis polystyla. 1R. Wagner. Isis, 1853, p. 256, Taf. X1.; also Icones zoot. Tab. XXXIV. fig. 16. 2 Lowén. Wiegmann’s Archiy. 1837, I. p. 321, Taf. VI. fig. 19-25. 3 Steenstrup. Ueber d. Generationswechsel, p. 20, Taf. I. fig. 41-47. 4 According to Sars (Beskrivelser. loc. cit. p. 6,° Taf. I. fig. 3), these remarks are also true of Co- rymorpha nutans. Laguncula, &c., Mém. Acad. Royale de Bruxelles, XVIII. ; also, Recherch. sur l’Anat. la Physiol. et le développement des Bryozoaires, Ke. Ibid. XIX.). See also Ad/man, Report Brit. Assoc. 1850, p. 320. — Ep. ‘ t (§ 44, note 2.] According to my own obser- vations, the Actiniae have both individuals which -are hermaphrodites and those of one sex alone. — Eb. 52 THE POLYPL $ 46. The and Sertzdarice a le -cel ae and branches sexless individuals. Bui m the amgies of these branches cells of another form, and contaiming many spherical individmals, $ Accoriime to Krohn (Waller"s Arch. 3825, p. 974), as probate chet in Compaonuiarie uni Ser- Ghe metusnifi females of this for Spawn. (AGGitionsl moe ae} 45] Whe serie: of Ghose Bits, Ghe sesiess ) ining: of youu, thas ‘heen imcreassi sererel more recent re aie relations here spoken of anf che conjeccures ic pardidies af 2 corcerie—-fomn heve been $$ 47, 43. THE POLYPL 53 § 47. body. Sometimes, however, they are attached longitudimally by ome of their borders. like a attached directly to the sides of the body. into the cavity of the - In Coralls having individeals of both sexes, fecundation takes place im the cavities of their bodies, which connect with each other.” With the others, however, the individuals of which are of Ome ==z alone. the water is the medium of fecundsiicn, ing the spermatic particles unaffected to the ezzs; and this bemg performed by the aqueous circulation mentioned, 1 jon takes § 48.4 The variaiions of the internal genital organs im the different families are as follows - Compeesicat: wih thee fee, throwsh winch SBe specmate perceés pass Fame Pwo. p- 673, Sz 4. A at ie the covey of the body of Se ek (se Bordémazs, 4 2 Sc Sat XE 1533_ p 1957) aed fie parte Geese a fe eeoe- *(§ 8) Bae wets west Sao d Qiheeed weciet: of Shes es, Sect asi oe aed She we, Ss wees Pc: ~ Secs 3 eed 4ctrais), sees csc (4etreesis), EE 7(§ 4 mote 1) My ews wee 2 BS @uses ths Brycess & is Iome-ciioes WER Aices bere Shown me fh WE Aegis SST mela. F camect theoweSore aerece wih Adiitker separate. The sock i ore ss ce o4 THE POLYPI. $$ 49, 50. transparent ring. In Alcyonella and Plumatella, the eggs are of an oval shape, and of a dark-brown color, In Cristatella mirabilis, Dal. (Crista- tella mucedo, Cuv.), they are lenticular and clear brown, and have this re- markable peculiarity ; © Upon both sides of the encompassing ring are a number of double-pointed hooks, which, at first, are imbedded in a gela- tinous substance ; but as this last is dissolved by water, they become free, and adhere to plants and other bodies. 2. With many Anthozoa, having a cavity of the body, the sexual or- gans are attached in the form of bands along the external face of the stomach. These are numerous, and during the epoch of reproduction their free borders are often plicated, and have a botryoidal aspect. This form is quite apparent in the Actznzae, where these organs are contained in sep- arate chambers of the cavity of the body. The same is true of the Ed- wardsiae. With Veretillum and Alcyonium © these organs form mesen- teric divisions which descend deep into the cavity of: the body. 3. In Alcyonidium elegans and Tubipora musica these organs are attached to the internal surface of the cavity of the body, and have a pli- cated mesenteric form.“ § 49. The laying of the eggs takes place in different ways with those Polyps having internal sexual organs. With the Bryozoa it probably occurs through the openings near the anus.” With the Anthozoa, however, they pass into the stomach through its abdominal orifices, and thence are ejected through the mouth. In the viviparous Actznza, the young, devel- oped at the base of the stomach, are expelled in the same manner. § 50. If. Many Anthozoa, which have no general cavity of the body, have external sexual organs. 2 Raspail, loc. cit. pl. XII. fig. 10-12, pl. XIV. fig. 4-8, and pl. XV. fig. 5. 3 Turpin and Gervais, Ann. des Sc. Nat. VIL. 1837, pl. IIT. A. fiz. 2-4, and pl. IV. A. fig. 1-6. 4 Wagner. Wiegmann’s Arch. 1835, I. Taf. ILI. fig. 1 ; also Icones zoot. Taf. XXXIV. fig. 22. 5 Quatrefazes. Ann. d. Sc. Nat. loc. cit. pl. I. fig. 7, and pl. IT. fig. 10. 6 Carus and Otto. Erlauterungstafeln, Heft. TV. Taf. I. fig. 19; also Wagner, Icones zoot. Taf. XXXIV. fig. 2. 7 Milne Edwards. Ann. d. Sc. Nat. loc. cit. pl. XIV. fig. 4; pl. XV. fig. 6, 8, and pl. XVI. fig. 3-5. 8 Ibid. p. 329, pl. XII. fig. 8, pl. XIII. fig. 2, 7. 9 Rymer Jones. Outlines, loc. cit. p. 36, fig. 9, after Lamouroux. 10 Kélliker’s observation upon the sexual organs *[§ 48, note 10.] With the Actinina, some of the lamellae which partition off the visceral cavity are margined each by a white, capillary, convolut- ed cord. Itis attached to the lamellae by a thin, mesentery-like membrane. These cords are the testicles. Between the spermatic lamellae are oth- erg similarly arranged, which are the ovarian, on This is especially true of Hydra, where in the of Alcyonidium gelatinosum, Johnst. (Halo- dactylus diaphanus of Farre), is quite remarka- ble; for he found them wanting in the isolated in- dividuals, but scattered here and there, in the form of small round sacs, in the fleshy substance of the corallum— some being ovaries, others testicles. But he is in doubt whether or not their contents are emptied into the cavity of the body or upon the outer surfaces (Beitr. loc. cit. p. 46).* 1 See, for Alcyonella stagnorum, Meyen (Isis, 1828, p. 1228). 2 Rathké has often found spawn in the stom- ach of Actinia (Reise Bemerk. aus Taurien, zur Morph. 1857, p. 10, and Beitr. zur vergleich. Anat. u. Physiol. in the neuesten Schrift. d. na- turf. Gesellsch. zu Danzig, III. Hft. IV. 1842, p. 112). which are situated the ovaries. With the Zoanthi- dae the relations are of the same general nature; but with the Tubipora, Dana found six ,spermatic to two ovarian lamellae. See Dana, loc. cit. p. 43, pl. XXX. fig. 3, b, c, d, e, f, and pl. LIX. fig.1,b. — Ep. $ 50. THE POLYPI. 55 same individual during the time of heat both ovaries and testicles are de- veloped upon the external surface of the body. In the place where the eggs are to appear,” the transparent and color- less skin rises in the form of swellings, under which the vitelline mass gradually forms. These end each in the form of an excrescence, which, being constricted at its base and rounded, has the shape of an egg. At the point of constriction there is formed from the body of the Polyp a kind of cupel, in the cavity of which the vitellus rests by a small portion of its surface ; at this point the skin becomes thin, and ultimately appears like an arachnoid membrane enveloping the egg. In this last neither a germinative vesicle nor dot has been discovered. Its separation is preceded by a thinning of its surrounding membrane, after which the vitellus is im- mediately clothed by a gelatinous substance. In Hydra vulgaris its whole circumference 1s covered by obtuse prolongations of this kind, which, after an increase in length, divide, each once or more, at their extremity, and so present a dentated appearance. The arachnoid membrane finally bursting, the detached egg becomes fixed to some body, whilst the gelatinous coat entirely disappears. This is equally true of Hydra viridis, with the exception that here the vitelline prolongations are very short and compact. - In these same individuals testicles are developed also. Between the base of the tentacles and the place of the appearance of the egg, there: are developed small conical prominences, on the apex of which is a papil- la. This has an orifice which leads into an internal cellular cavity. This is the real testicle, wherein are found spermatic particles composed of a body, or head, to which is attached a very movable tail. These particles easily escape through the orifice, and circulate in the water surrounding the Polyps filled with eggs. The number of these testicles in a single individual is not definite.” * 1In the arm-polyps, gemmation always pre- 4 Wagner, Icones zoot. Tab. XXXIV. fig. 10, cedes propagation by eggs. b, b. In Hydra vulgaris I have counted fifteen 2 The eggs of Hydra were long ago observed by testicles ; another individual had seven eggs and Bernhard Jussieu (Abhandl. d. schwed. Akad. eleven testicles ; and a third, four eggs and twelve 1746, VIII. p. 211). But afterwards they were testicles. regarded as exanthemata of this animal (see Roe- [Additional note to § 50.] Other examples of sel, Insektenbelust. Th. III. p. 500, Taf. LXXXII. Anthozoa having external genital organs in the fig. 1, 2). Their true nature was lately first form of egg or sperm capsules have been observed pointed out by Ehrenberg (Abhandl. d. Berliner by Van Beneden (Rech. sur Pembryog. d Tubul. Akad. 1836, p. 115, Taf. IT.). pl. V. VI.), Rathké (Wiegmann’s Arch. 1844, I. 8 The testicles of Hydra were known to the elder= Taf. V.), and Sars (Faun. littoral. Norveg. p. 7, naturalists, but were taken for an eruptive disease Tab. II.), with Hydractinia, Coryne and Podo- (Trembley Abhandl. zur Geschicht. einer Polype- coryne. See also the facts collected by Frey and nart, p. 264, Taf. X. fig. 4, and Roesel, loc. cit. p. Leuckart (Beitr. &c. p. 28). These egg or 602, Taf. LX XXIII. fig. 4). Latterly this same sperm capsules may, moreover, be regarded as error has been continued (Laurent in Froriep’s imperfect male or female individuals, and then the neuen Notizen, 1842, No. 513, p.104). To Ehkren- porters of these capsules may be considered, being berg is due the first description of their true nature — sexless individuals like those mentioned in § 44, (Mettheil. aus den® Verhandl. d. Gesellsch. naturf. in the category of nurse-like generations which, af- Freunde in Berlin, 1838, p. 14). ter a more or less complete development, produce generations with sex. * [At end of § 50.] The so-called ova, mentioned particles for their development. It is also worthy above in the text, may be justly questioned as be- of remark, in this connection, that these ova sprout ing true ova, for we know of no real ova which do from the same part of the body in which eggs are not contain a germinative vesicle. Then, again, developed." Thomson, however (Edinb. New simple oval masses of cells as they are, they would Philos. Jour. 1847, p. 287), speaks of having ob- exactly resemble the bud-like eggs of Aphides, and served the granular mass contained within these the “hibernating eggs” of Daphnia and some of so-called eggs divide and subdivide like a proper the Rotatoria, all of which are properly gemmae, _vitellus, and this while still within the capsule, and and do not require the agency of the spermatic attached to the parent animal. This does not 56 THE POLYPI. $$ 51, 52. § 51. III. There are Polyp-colonies which contain two kinds of individuals, those which are sexless, and those having sexual organs only at certain epochs. These last are campanulate or medusoid, and their sexual organs are developed in various parts of their body. In Coryne™ and Syncoryne,” the eggs appear upon the external sur- face of the stomach, then fall into the cavity of the mantle, through the openings on the border of which they escape into the water. In the medu- soid individuals of Coryne fritillaria and Corymorpha nutans, the sexual organs appear to be formed in the angles of the borders of the disc, and in Campanularia in the disc itself. * § 52. As to the embryonic developments of Polyps, it is probable that in a great number (perhaps all) there is a metamorphosis. The development commences by the usual segmentation of the vitel- lus,” by which it is ultimately converted into an ovoid, contractile body ; this turns upon its longitudinal axis by means of cilia, with which it is en- tirely covered, swimming about like many Infusoria. These embryos, often developed in the mother, have sometimes been taken for swimming eggs. Afterwards they attach themselves to some body, and usually lose their cilia; the free extremity of their body opens, allowing the escape of the Polyp, which, in the mean while, has been developed in the interior, with its arms in front. Many of the Polyps thus produced multiply by gemmation, and thus become the foundation of new Polyp-colonies. 1 Wagner (Isis 1833, Taf. XI. fig. 8). 2 Loven (Wiegmann’s Archiv. 1837, I. Taf. VI. fig. 19, 20). a Steenstrup, Ueber d. Generationswechsel, p. 23, 24. 1 It is indeed singular that with Hydra the divi- sion of the vitellus takes place before the eggs are either detached from the body, or are surrounded by a dentated envelope. I do not yet know at what epoch the development of the embryo commences, for I have never seen the young come forth. It is impossible for me to say whether or not these Polyps experience a metamorphosis. Padlas (Ka- rakteristik d. Thierpflanzen p. 53) has seen the young Polyps come forth from the egg, but he gives no description. Laurent, also, only says that the young animal escapes formed from the egg, with- out describing the embryo (Froriep’s neue Notizen, No. 518, pl. 101). The segmentation of the vitellus has been observed. by Van Beneden in the eggs of Pedicellina. Sve his Rech. sur Vanat. d. Bryo- zoaires (Suite) loc. cit. XIX. p. 18, pl. IL. 2 As would be inferred from his description, Cav- olini (loc. cit. p. 47, 50, Taf. TV. fig. 7-10 and 13- 15) has observed similar embryos to those of Gor- gonia and Madrepora. His descriptions of various eggs of Sertularia leave no doubt that they also make the matter any more clear ; for, even admit- ting that they are proper ova, it is difficult to con- ceive how the impregnation (of which the segment- ation for a definite result is the sequela) could take place while the ova are thus buried in the capsules. The subject requires further research. See also Steenstrup, Untersuch. ib. Hermaphroditismus, p. were embryos (Ibid. p. 56, 80 et seq.). Grant also has taken for eggs the contractile, ovoid embryos of Lobularia digitata, which he has seen issue from the mouth of this animal (Froriep’s Notizen 1828, No. 440, p. 340). Meyen has well described and figured the ciliated epithelium of those of A/- cyonella stagnorum (Isis 1828, p. 1228, Taf. XIV. fig. 4, 5). Loven has observed the elon- gated embryos of Campanularia geniculata, and has taken the division of the vitellus for a sponta- neous fissuration of the embryos (Wiegmann’s Archiv. 1837, I. p. 260, Taf VI. fig. 18,14). Ac- cording to Rathke, who has seen movable tenticu- ,lar embryos in the stomachs of dctinia, these polyps experience a metamorphosis (Reise Be- merk. aus Taurien zur Morph. p. 10, Taf. 1, fig. 12). 4 This metamorphosis has already been observed by Cavolini (loc. cit. p. 261, Taf. VI. fig. 7) with Sertularia racemosa, and more lately by Lowén (loc. cit. p. 261, Taf. VI. fig. 15-17) with Campa- nularia geniculata. There are always developed in the interior of the embryos of Alcyonella stag- norum two Polyps, even before the first have es- caped from the egg ; when the escaped embryo has become fixed, its skin bursts, and the Polyps escape, but are able to return again as into a mouth. 116, and Hancock, Ann. Nat. Hist. 1850, V. p. 282.— Ep. * (End of § 51.] See Schultze (Miller’s Arch, 1850, p. 57), who has found with Campanularia seminal capsules corresponding to those for egg- capsules pointed out by Lovén (loc. cit.).— Ep. § 52. THE POLYPI. 57 This metamorphosis is completed when the skin is covered by a brown and solid layer, and new indi- viduals are developed by gemmation from the two Polyps (See Meyen, Isis, loc. cit.). I have seen the development of the coralla of Cristatella mi- rabilis and Plumatella campanulata occur in the same way. With the Cristatedlae,gemmae of new Polyps are often seen to arise from the skin, even after the escape of the two Polyps, and before the young colony has become at all fixed. At this epoch of development these Polyps have been taken by Cuvier for a distinct species, and called Crista- tella mucedo. See Roesel, loc. cit. p. 559, Taf. * (§ 52, note 3.] The embryonic development of the Bryozoa has been carefully wrought out by Van Beneden. See Recherch. sur les Bryozoaires, XCI. ; and Turpin, Ann. d. Sc. Nat. VIL. 1837, p. 65, pl. II. and IIT. Infusoria-like embryos have been observed also by Steenstrup (Untersuch. loc. cit. p. 66, Taf. I. fig. 21) with Coryne squamata, and by Sars (Faun. littoral. Norveg. p. 7, Tab. II. fig. 7-11) with Po- docoryna carnea. The round eggs moving about by means of cilia, which Reid (Ann. of Nat. Hist. XVI. p. 392, 397, pl. XII. fig. 9, 18) has observed in the visceral cavity of Pedicellina echinata, and in special capsules with Flustra avicularis, were probably embryos also.* &c., Mém. ‘Acad. Bruxelles. XIX. See also AJ/- man, Report, loc. cit. 1850, p. 322 — Ep. BOOK THIRD. ACALEPHAE. CLASSIFICATION. § 53. Tue popy of Acalephae is composed of a transparent, gelatinous sub- stance, quite resembling the Corpus vitrewm of the eyes of vertebrata. By desiccation it almost entirely disappears, there remaining only a dry cel- lular tissue, by which the form of the animal is imperfectly preserved. These animals swim freely in the sea after having attained their develop- ment. . In the arrangement of their organs in ray-like processes radiating from a common centre or a longitudinal axis, and where also is situated the digestive apparatus, the quaternary system prevails. Copulatory organs are always wanting. The classification is based, according to the system of Eschscholtz, upon difference of external form, and upon the structure of their digestive and locomotive organs. ORDER I. SIPHONOPHORA. They take in their food by means of numerous tubes, which exist in place of a stomach. Locomotion is aided, generally, by certain cartilagi- nous capsules. Famity: Drenyrar. Genera: Diphyes, Ersaea. Famity: PrysopHoripas. Genera: Physophora, Stephanomia. Famity: Purysanipar. Genus: Physalia. Famity: VELELLIDAR. Genera: Retaria, Velella, Porpita. § 53. THE ACALEPHAE. 59 ORDER II. DISCOPHORA. They have a simple central stomach, and move by means of discoid or campanulate contractions of their body. Famity: Arquorrna. Genera: Aeguorea, Polyxenia. Famity: Ocranrpae. Genera: Oceania, Cytaeis, Thaumantias. Famity: GERYONIDAE. Genus: Geryonia. Famity: Rutzosromipar. Genera: Cephea, Cassiopea, Rhizostomum. Famity: Mepusrpar. Genera: Pelagia, Cyanea, Chrysaora, Medusa, Aurelia, Ephyra, Stheno- nia. ORDER III. CTENOPHORA. Their mouth and stomach is simple and central, and they move by means of cilia arranged in longitudinal rows. Famity: Brrorpas. Genera: Bero’, Lesueuria, Medea. Famity: MNeEmMraDAr. Genus: Eucharis. Famity: CALbiaNIRIDAE, - Genera: Cydippe, Cestum. BIBLIOGRAPHY. Eschscholtz. System der Acalephen. Berlin, 1829. Lesson. Histoire naturelle des Zoophytes. Acaléphes. Paris, 1843. Wil. Horae tergestinae oder Beschreibung und Anatomie der im Herbste, 1843, bei Triest, beobachteten Azalephen. Leipzig, 1844. Ehrenberg. Ueber die Acalephen des rothen Meeres und den Organis- mus der Medusen der Ostsee, in the Abhandlungen der Berl. Akad. 1855. Mertens. Beobachtungen und Untersuchungen tiber die beroéartigen Acalephen, in the Mémoires de Académie des Sciences de St. Peters- burg, 6me series, Tom. II. 1833, p. 479. Also, in Isis, 1836, p. 311. Brandt. Ausfirliche Beschreibung der von C. H. Mertens auf seiner Weltumsegelung beobachteten Schirmquallen, nebst allgemeinen Bemerkung- 60 THE ACALEPHAE. $ 54. en uber die Schirmquallen tberhaupt, in the Mém. de l’Acad. des Se. de St. Petersburg, 6 ser. Tom. IV. 1838, p. 239. Milne Edwards. Observations sur divers Acaléphes, in the Ann, des Se. Nat. 2de Sér. Zoologie. Tom. XVI. 1841, p. 194. ADDITIONAL BIBLIOGRAPHY. Forbes. A monograph of the British naked-eyed Medusae, with figures of all the species. London, Ray Society, 1848. Contains many anatom- ical details. Agassiz. Contributions to the Natural History of the Acalephae of North America. Part [.— On the Naked-eyed Medusae of the shores of Massachusetts, in their perfect state of development. Part If. —On the Beroid Medusae of the shores of Massachusetts, in their perfect state of development. See the Mem. Amer. Acad. Arts and Se. vol. IV. 1850. Also, Twelve Lectures on Comparative Embryology, delivered before the Lowell Institute, Boston, 1848—49. Busch. Beobachtungen tber Anatomie und Entwickelung einiger wir- bellosen Seetniere. Berlin, 1851. [The above are among the most important larger works; but see, also, many papers of great value, to which I have referred in my notes. — Ep1- TOR. | CHAPTER IT. *. SKIN AND CUTANEOUS SKELETON. § 54. Generally, the body of the Acalephae is of a gelatinous substance, com- posed of polyhedral cells. In some species certain parts of the body have a cartilaginous hardness, but it is only in a few that there is found a carti- laginous or calcareous nucleus, comparable to a rudimentary skeleton. With the Diphyidie a large portion of the body has a cartilaginous density, and with the Physophoridae it is often surrounded by plates of a similar nature. The Velellidae have a nuclear skeleton, which in Rata- ria is a simple, elongated disc; but in Veled/a this disc, which is horizon- tal and of an elongated oval form, is surmounted by a vertical crest. The disc is composed of four pieces joined together by two sutures which cross each other obliquely. The crest, united to the dise along the whole length of the two sutures, and resembling the segment of a circle, is composed of two main pieces, joined in the middle by a third, which is shaped like a wedge.) . The disc situated under the skin of the upper surface of Porpita, and #1 Eschscholtz, loc. cit. Taf. XV.; and Lesson, Acaléphes, loc. cit. Pl. XII. fig. 1; also, Duperrey, Voyage loc. cit. Zoophytes, No. 6. fig. 1, A. A. $$ 55, 56. THE ACALEPHAE. 61 which encloses between its two lamellae numerous aérial canals, is said to be of a calcareous nature. All these discs have upon their surface markings of concentric rings and diverging rays. ‘ § 55. The Acalephae are surrounded by a very delicate epidermis. Upon various portions of the body, and especially upon the arms, the tentacles, the prehensile filaments and the cirri, there exist cilia and peculiar net- tling and prehensile organs. In those species having active irritating prop- erties the nettling organs are situated in a mass under the epidermis.” § 56. These nettling organs are generally composed of an oval capsule, con- taining a spiral filament which is thrown out from the slightest disturb- ance, and, together with its capsule, is detached from the skin.” In some species, there exist in place of these nettling organs others of a prehensile nature, consisting of an oval capsule in which is a stiff bristle. These last cause no burning sensation, but are the means by which these animals attach themselves to contiguous objects in a bur-like manner. They are situated, grouped in small masses, under the skin of most of the non-nettling Discophora, and their bristles project upon the cirri situated upon the border of the disc, upon the tentacles, the arms and the sexual organs. © 2 Eschscholtz, loc. cit. p. 176, and Lesson, loc. ~ cit. Pl. XII. fig. 3; also, Duperrey, loc. cit. No. 7, fig. 3. oh Wagener (Miiller’s Arch. 1847, p. 183, Taf. VIM. fig. 4, 5) has described the peculiar hair- like productions on the sides of Beroé and Cydippe. They have, near their free extremity, a multitude of pedunculate small buttons, inserted on a clavate swelling. 1 Wagner (Icon. zoot. Tab. XXXIII. fig. 8, 10, 11, A. B. C. and Ueber den Bau der Pelagia noctiluca, 1841.; also, in Wiegmann’s Archiv 1841. Th. I. p. 39) has found in Pelagia noctiluca that the nettling capsules are situated among the pigment cells beneath the epithelium of the disc. According to this author, Oceania, which has feeble nettling powers, has these capsules only upon the marginal filaments. Ehrenberg (Wiegmann’s Archiv 1841, Th. I. p. 71, Taf. ILI.) has failed to find these organs upon the non-nettling disc of Cyanea capillata, although they are found among their prehensile cirri, which have irritating power. With these, as with the hooked organs of Hydra, he thought the capsule was detached before the fil- ament. Will (Hore tergest. pp. 62, 65) did not find these organs in Cephea, except on the tenta- cles of the genital organs ; and in Po/yxenia only on the marginal filaments. Ké/liker (Beitrige, loc. cit. p. 41) has seen them also about the gen- itals of Chrysaora and Aequorea. The Siphonophora have only the prehensile fila- ments covered with them. Thus in Stephanomia, according to Milne Edwards (Ann. d. Sc. Nat. XVI. p. 223, Pl. VIII. fig. 9), they cover the whole surface of these last ; while in Physophora, Diph- yes and Ersaea, they exist only upon their en- larged portions, according to Philippi (Miiller’s Arch. 1843, p. 62, Taf. V. fig. 9), and Will (loc. cit. p. 79, 81, Taf. IL. fig. 23-25). * 2 Siebold (Beitrage zur Naturgesch. der wirbel- losen Thiere, 1839, p. 10, 91, Taf. II. fig. 39) ; also, Ehrenberg (Ueber die Acalephen d. rothen Mee- res, &c. &c., in the Abhandl. d. Berl. Akad. 1835, p. 205, Taf. IV-VIII.). He has compared these prehensile organs to suckers. According to Milne Edwards (Ann. d. Sc. Nat. XVI. p. 215), and Will (loc. cit. p. 80, Taf. IT. fig. 24), they are found also upon the body of Beroé, and at the extremity of the prehensile filaments of Diphyes and Ersaea. } According to Wiil, also (loc. cit. p. 51, Taf. I. fig. 19, A. B.), the prehensile filaments of the Cten- ophora have two kinds of capsules; one, which upon the least touch bursts and discharges a liquid; the other, of a somewhat different appearance, and which contains a delicate, viscous filament. Similar filaments, he says, are found upon the warts on the body of Eucharis. * For these nettling organs and their intimate structure, see my note under § 27, note 1.— Ep. 6 62 THE ACALEPHAE. $$ 57, 58. CHAPTER II. MUSCULAR SYSTEM AND ORGANS OF LOCOMOTION. § 57. The Acalephae have a distinct muscular system. Their contractile sub- stance is composed of a net-work of elongated, slender filaments and bands; these, in the utriculoid species, are arranged in a longitudinal and annular manner, but in those of a discoid and campanulate form they are disposed in a circular and radiate manner. In the extremely irritable tentacles and tactile filaments, the longitudi- nal fibres abound.” Each fibre is smooth when relaxed, but during contraction appears trans- versely wavy and plicated. § 58. The contractile and aérial natatory vesicles, which are found in the Phy- sophoridae,® and the movable lamellae of the Ctenophora, may well be regarded as accessory organs of locomotion. These last, which are arranged in rows upon the sides of the animal, and which by some anatomists have _ been regarded as respiratory organs, are not simple cutaneous lobes, but are composed of very long cilia closely united together, and the motion of which is voluntary with the animal.© 1 7Vill (loc. cit. p. 48, Taf. I. fig. 11) has observed in the contractile excrescences of the Hucharis, not only circular fibres and numerous longitudinal muscles, but large transversely-flattened ones, which were bound together by oblique bands. 2 Will, loc. cit. p. 47, 63, Taf. I. fig.138, Accord- ing to Wagner (Ueber den Bau, &c.; and Icon. zoot. Tab. XXXIIT. fig. 30), the muscles of the Discophora have always the transverse striae. The cartilaginous natatory pieces of the Siphon- ophora play a completely passive part in the act of locomotion. The swimming is exclusively per- formed by the energetic contractions of the mus- cular membrane which lines their cavity, con- stituting, therefore, a true natatory sac. See Sars Faun. littoral. Norveg. p. 42.* 1 Lately, it has been doubted if the Physophor- idae can siuk and rise in the sea by means of their natatory bladders, because they cannot exhaust the * [§ 57, note 2.) For the muscular system of the Acalephae, see also Forbes (loc. cit. p. 3), and Agassiz (loc. cit. p. 236). This last-named author has described this system with full details in many genera. It is much more complex than has hitherto been supposed, and I must refer for the details to the memoir in question. / contained air. According to Olfers (Abhandl. d. Berl. Akad. 1831, p. 157, 165, laf. I.), there are two of these bladders in Physalia, one of which only has an opening. Philippi (Miiller’s Arch. 1843, p. 63) has found neither internal nor exter- nal opening to the bladder of Physophora tetras- ticha. In Stephanomia it would not appear, according to the description of Milne Edwards (Ann. d. Sc. Nat. XVI. p. 218, Pl. VIII. fig. 1. b. 2), that this organ had an external opening. Couch (Froriep’s neue Notizen, No. 275, p. 129) denies that Physalia has the power to control the air of its bladder. See also below, § 65. 2 Grant, Trans. Zool. Soc. London, f. 1835, p. 9.5 Sars, Beskrivelser loc. cit. Pl. VIII. fig. 18, e.5 Milne Edwards, Ann. a. Sc. Nat. XVI. p. 201, 216, PI. IV. fig. 2,3, Pl. VI. fig. 1.c.; and WiiZ, loc. cit. p. 9, 56, Taf. I. fig. 5. In regard to the structure of these muscles, Agassiz remarks : ‘¢ With all the power of the best Oberhduser Microscope, I have been unable to dis- cover the slightest indication of striae on the mus- cular cells; nevertheless, it cannot be doubted that they are voluntary muscles.” To this view I may add my own of the same nature. — Ep. §$§ 59, 60. THE ACALEPHAE. 63 CHAPTER III. NERVOUS SYSTEM. § 59. A nervous system has been found in many Acalephae. With the Cteno- phora the cesophagus is surrounded by a ring formed of eight ganglia, and at the opposite extremity of the body there is a simple ganglion. Five nervous filaments pass out from these ganglia, and along the sides of the body are nervous fibres, which ultimately divide into delicate threads. The tentacles of Medusae are supplied with nervous filaments which issue from a ganglion situated at their base. CHAPTER IV. ORGANS OF SENSE. § 60. With many Acalephae, there are, upon the borders and extremities of 1These eight ganglia, which are connected together by delicate cords, were first observed by Grant (Trans. Zool. Soc. Lond. I. p. 10) in Cydip- pe pileus. Compare, also, Wagner, Icon. z0ot. Tab. XX XIII. fig. 37, A. B. From each of these ganglia two nerves pass off to the side, while a third, traversing the interior of the body, and hay- ing two or three swellings, is finally distributed to the intestine. Patterson (Lhe Edin. new Philos. Jour. XX. p. 26), and Forves (Ann. of Nat. Hist. 1839, p. 145), have also observed the oesophageal ring in Cydippe, but did not perceive the ganglia. 2 Milne Edwards (Ann. des Sc. Nat. loc. cit. p. 206, Pl. LV. fig. 1) has observed at the poste- rior extremity of the body of Lesueuria vitrea (a new Beroid) a ganglionic body which sends * {§ 59, note 3.] The nervous system of the Acalephae has been successfully studied by Agassiz upon several genera (Hippocrene, Tiaropsis, Staurophora). Wis results are new, and different from those of previous observers. I cannot do bet- ter than to quote his words: ‘There is, unques- tionably, a nervous system in Medusae, but this nervous system does not form large central masses, to which all the activity of the body is referred, or from which it emanates. There is no regular com- munication by nervous threads between the centre and periphery and all intervening parts; and the nervous substance does not consist of heterogene- ous elements, of nervous globules and nervous threads, presenting the various states of complica- tion and combination, and the internal structural differences, which we notice in the vertebrated ani- mals, or even in the Mollusca and Articulata.” out in front four filaments ; and upon the sides of this animal a nervous cord, from which pass off elicate branches at regular intervals. At the pos- terior extremity of the body of Cydippe, Eucha- ris and Medea, Will (Froriep’s neue Notizen, No. 599, 1843, p. 67, and Horz tergest. p. 44) has likewise observed a round, yellowish ganglion, with four prolongations, from which pass off twenty-five or thirty nerves. 8 Ehrenberg has found along the entire border of the disc of Medusa aurita, and between each two tactile filaments, a bifid nervous ganglion. He affirms to have seen also two others similar, at the base of each tentacle surrounding the genital organs. See Abhandl. d. Berl. Akad. 1835, p. 203, Taf. LV. fig. 1, x.; and Mudler’s Arch. 1834, p. 571.* “In Medusae the nervous system consists of a simple cord, of a string of ovate cells, forming a ring around the lower margin of the animal (Pl. V. fig. 11, 2, 4, 5), extending front one eye-speck to the other, following the cireular chymiferous tube, and also its vertical branches, round the upper portion of which they form another circle. The substance of this nervous system, however, is throughout cellular, and strictly so, and the celis are ovate. There is no appearance in any of its parts of true fibres” (loc. cit. p. 232). That this is the nervous system seems placed beyond all controversy ; for, in a private letter, Agassiz has informed me that in a new genus (Rhacostoma), living on the shores of Massachusetts, he has seen this system at night as an illuminated diagram. — Ep. 64 THE ACALEPHAE. $ 60. their body, button and tongue-like organs, which, as they are connected with neighboring ganglia, may well be regarded as organs of sense. Their essential structure’ is a membranous capsule, containing a clear liquid, in which are suspended crystalline corpuscles. These organs, having sometimes a red pigment, have been taken for eyes; but, as most of them are without pigment, and as the crystalline corpuscles behave in acid like the Otolites of the higher animals, they have more recently been better designated as organs of hearing. ; The eight marginal, tongue-like bodies, found upon the dise of Medusa aurita, have been regarded as eyes. The sole fact for the support of this opinion is the presence of pigment; for the small hexagonal crystals, irreg- ularly scattered in the interior of these bodies, would scarcely allow them to refract the light like a erystalline lens. The Ctenophora have only a single organ of this nature, and which is situated near the ganglion at the posterior end of the body. It has been regarded both as an eye and as an organ of hearing.© With many Discophora, these organs appear as pale-yellow, or even colorless marginal corpuscles, having more or less calcareous bodies. It is yet doubtful whether the otolites of the Acalephae perform the same movements as those of the acephalous and gasteropod mollusca.® 1 These marginal corpuscles, already observed in the Medusae by Gaede (Beitrage zur Anat. u. Phys. der Medusen, 1816, p. 18, 28), and by Rosen- thal (Zeitsch. f. Physiol. Bd. I. Hft. 2, 1825, p. 526), were first described as eyes by Zhrenberg. See Miiller’s Arch. 1834, p. 571, and Abhandl. d. Berl. Akad. 1835, p. 190, Taf. IV. V. 2 Milne Edwards has called this body, in Lesu- euria vitrea and Beroé Forskalit, “* Organe ocu- liforme” (Ann. a. Sc. Nat. loc. cit. p. 206, 211, Pl. IV. fig. 1, k. and Pl. V. fig. 4, i.). According to Will (Froriep’s neue Not. No. 599, p. 67, and Hore tergest. p. 45, Taf. I. fig. 2, 4, 20, b.), the red pigment of these organs is entirely wanting in Beroé, Eucharis and Cydippe, while the hexago- nal calcareous corpuscles are very numerous —a fact leading him to conclude that these organs are auditory vesicles. 8 According to Wagner (Ueber den Bau, &c., and Icon. zoot. Tab. XX XIII. fig. 31, g. 23, c. and 25), these corpuscles are pale-yellow in Pelagia noctiluca, and colorless in Oceania, Cassiopea and Aurelia. In Cephea, Will has observed only pale-yellow corpuscles, filled with crystals. And, according to him (loc. cit. p. 64, 68), the colorless pedunculated marginal vesicles of Polyxenia leu- costyla contain, each only a single round otolite, while those of Cygaeis polystyla contain numbers, colorless or yellow, and of irregular forms. He has also observed (loc. cit. p. 72, Taf. II. fig 9, 10) that in Geryonia the number of these otolites varies from one to nine. Milne Edwards (Ann. * [§ 560, note 4.] The organs of sense of the Aca- lephae have been the objects of much study of late, and to Agassiz we are indebted for the most minute researches on these obscure points. He has shown the eye-specks to be undoubted organs of sense, from their connection with the nervous system. With the naked-eyed Medusae, he regards them light-perceiving instead of auditory organs. In regard to the single organ found with the Cteno- phora, and which Frey and Leuckart have re- d. Sc. Nat. XVI. p. 196, Pl. I%e.) has observed upon the margin of the dise of Aequorea violacea vesicles containing two or three spherical corpus- cles, and which, probably, are auditory organs. According to Sars (Viegmanr’s Arch. 1841, Th. 1. p. 14, fig. 60), and Wild (loc. cit. p. 75, Taf. IL. fig. 21, A. B.), these marginal corpuscles are found upon young Medusae belonging to Ephyra. 4 Will has never observed with the Otolites of Acalephae similar movements to those of mollusca. Kéiliker (Froriep’s neue Not. No. 534, p. 82) has observed vibratile cilia upon the inner surface of the marginal corpuscles of Pelagia, Cassiopea, Rhizostomum and Oceania, which are pyriform, and contain many calcareous crystals. In the pedunculated vesicles of Geryonia, which contain only a single crystal, these cilia are absent. In none of the Medusae has he found collections of pigment, and in Oceania (nov. spec.) only he has observed a mass of brown pigment cells upon the external and superior surface of the base of these corpuscles ; in the centre he perceived a round transparent body, and upon the upper surface a circular opening, so that the whole closely resem- bles an eye, there being, moreover, a kind of pupil- lary opening, and the traces of an optic nerve from a ganglion. According to the observations of Frey and Leuckart (Beitr. &c. p. 39), the group of otolites contained in the auditory organ of a Cydippe per- form oscillatory movements, due evidently to vibra- tile cilia situated on the auditive capsule.* cently declared to be of an auditory nature, he remarks : ‘*f am inclined to consider this organ, or this speck, as something similar to the central col- ored speck which occurs in the middle of the disc in Discoid Medusae, and which is particularly dis- tinct in young animals soon after they have been detached from the polyp-like stem on which they grew, as a remnant of the connection which exists between the mother-stem and its progeny in those Medusae which multiply by alternate generations.” » $ 61. THE ACALEPHAE. 65 CHAPTER V. DIGESTIVE APPARATUS, § G1. The digestive apparatus of the Acalephae is formed after several very different types. The mouth is sometimes single and central, or there may be many of them. It is often surrounded with arms and retractile filaments, which are endowed with the prehensile and nettling organs just described. The digestive cavity, which is always lined with ciliated epithelium, has distinct walls, which are united immediately to the parenchyma of the body, leaving, therefore, no surrounding cavity. With ‘those having a single mouth the stomach is of a variable size, and has often caecal appendages, With Beroé,” the mouth is very large and , free from tentacles, and opens into a very spacious stomach which occu- ' pies nearly the whole body. But with Cestwm, Cydippe and Lesueuria, the stomach is smail, and appears like a cavity in the body;® and with Cytaeis, Thaumantias and Geryonia, it is likewise small, and has the shape of a tubular projection. That of Medusa has four saccular folds,” that of Pelagia® _ and that of Cyanea thirty-two. When the mouths are numerous, either, as in the Ahinstonnase,® there are many canals which conduct the food through the arms upon which the mouths are situated into the central stomach; or, as in the Siphonophora, each mouth opens into a particular tubular stomach. With these last, however, a certain number of their tentacles are hollow, and have a mouth at the extremity. As it has been observed that these suck in food and digest it, their orifices have been regarded as mouths, and their cavities as stomachs, © 1 Milne Edwards, Aun. d. 8c. Nat. XVI. pp. 5, 6. 2 Eschscholtz, loc. cit. Taf. I. IL.; and Miine Edwards, \oc. cit. Pl. III. 8 Will, loc. cit. Taf. IL. 4 Baer, in Mecker’s deutschs. Arch. VIII. 1823, Taf IV. fig. 2; also, Ehrenberg in Abhandl. a. Berl. Akad. 1835, Taf. IL. fig. 1. 5 Wagner, Icon. zoot. Tab. XX XIII. fig. 5. 6 Gaede, loc. cit. Taf. II. 7 Eysenhardt, Noy. Act. physico-med. X. part II. p. 391, Tab. XXXIV. fig. 1 (Rhizostomum Cuvieri). 8 This is so, for examples, in Diphyes (Will, loc. cit. Taf. II. fig. 22); in Physalia (Olfers Abhandl. d. Berl. Akad. 1831, p. 162, Taf. I.) ; in Stephano- mia (Milne Edwards, Ann. d. 8c. Nat. XVI. Pl. VIt. IX. X.); and in Physophora (Philippi, Miiller’s Aych. 1843, Taf. V. fig. 1, 4) (Loc. cit. p. 316.) On a preceding page he says: “That this may be the case seems probable when we consider the relation of the two sorts of appa- ratus in the two types. The upper nerveus ring in Sarsia bears the same relation to the central ali- mentary cavity, and to the pigmented disc, that the ganglion and eye-speck of Beroé bear to the chy- 6% Philippi, however, affirms that in this last genus these canals are organs of absorption, and that the true stomach, which has a simple mouth, is concealed at the base of the tentacles (loc. cit. p. 63, Taf. V. fig. 10). I think, however, that this opening belongs to the respiratory system, as also does a similar opening in Velella and Porpita, which Lesson (Voyage de peeps cit. p. 49, 56, No. 6, fig. B. ; and No. 7, fig. C. C.) has regarded as amouth, The tubular tentacles of these animals are noth- ing but stomachs ; and Lesson himself has called them “poches stomacales,” since they digest food. It would, moreover, be strange that these organs, which, in Physalia, have been admitted to be stomachs, should perform another function in Physophora, Velella, and Porpita, where their structure is the same. But further researches are miferous system, which opens above its gelatinous disc, notwithstanding these openings.” (p. 248.) This point, fully as interesting from its zoological importance as from its morphological relations, ean be settled only by a knowledge of the embryol- ogy of these animals. — Ep. 66 THE ACALEPHAE. $ 62. The Acalephee have no true digestive tube. But, as such, has been regarded a system of vascular canals filled with water, and which, de- parting from the stomach, traverse the whole body. But these, although sometimes seen to contain feeces, seem to belong more properly to the respiratory system. In none of the Acalephae has there been found anything like an hepatic organ, CHAPTER VI. CIRCULATORY SYSTEM. » 6/62: ff Until lately, the longitudinal and circular canals which, in some Acale- phae, are spread out through the entire body, have been re belonging to a vascular, sanguineous system. garded as But more recently these have properly been considered as aquatic-respiratory organs, there having been found, moreover, other vessels of exceedingly thin walls, and of a sanguineous nature. These last constantly accompany and surround in a tubular manner the aquiferous canals; and it is quite rare that small branches are distributed to the general parenchyma. The delicate walls of these vessels have neither longitudinal nor circular fibres, neither are they lined with ciliated epithelium. They circulate a required to thoroughly settle this point. See below, the respiratory organs. See also Hollard, who unhesitatingly regards the canals, which, with Ve- lella, communicate externally by a central opening, as a digestive cavity, and thinks he has observed in their walls brownish spots representing the hepatic cells; see Ann. d. Sc. Nat. Ili. 1845, p. 249, Pl. LV. bis. 9 The aquiferous canals of the respiratory sys- tem having been regarded as intestinal tubes, their orifices, which in the Ctenophora are situated at the extremity of the body, and in the Discophora upon the borders, have been considered as anal openings; and especially so, since in these two orders, accidental feces in these canals are expelled through these orifices. See Will, loc. cit. p. 28, * [§ 61, note 9.] Upon the nutritive system of the Acalephae, see Forbes (loc. cit. p. 4), but especially Agassiz (loc. cit.), who has studied the subject with conscientious care. There is no dis- tinction between the alimentary canal proper and the vascular system, for the one opens by large tubes into the other. The Acalephs, therefore, cir- culate chyme, and here we have the rudest form of circulation. If this idea is once well considered, the relations of their nutritive apparatus in general will be quickly appreciated. The variations in the shape and form of the di- gestive apparatus are wide and numerous, but and Ehrenberg, Abhandl. d. Berl. Akad. 1835, p. 189, Taf. I. IV. fig. 2, z.* WW Acalephee possess an extraordinary digestive power, which is the more singuJar as no secretory organ has been found on the sides of their stomach. Mertens (Mém. d. PAcad. de St. Petersburg, loc. cit. p. 490, Taf. I. fig. 5, 6, a.; and p. 518, Taf. VIII. fig. 4, Taf. LX. fig. 1, f.), however, afiirms to have seen in Cestum and Cydippe four vessels in this situation, which are perhaps hepatic organs. The orange-colored cords found upon the sides of the stomach of Stephanomia, and which Milne Edwards (Ann. d. Sc. Nat. XVI. p. 222, Pl. VII. IX. X.) has taken for genital organs — may they not also be hepatic organs ? f their importance is. rather in Zoology. See Agas- siz for the details of Sarsia, Hippocrene, T'iarop- sis, Staurophora, Pleurobranchia, Bolina.— Ep. + [§ 61, note 10.] Kélliker (Siebold and Kélli- ker’s Zeitsch. 1V. Hft. 3,4, p. 318) has observed with Velella and Porpita a glandular mass, correspond- ing most probably to a liver. It had before been regarded as such by Delle Chiaje, but Kélliker has given it a special description. It consists of a brown mass which communicates with the bottom of the stomachal cayity by branched, anastomosing ducts. — Ep. $ 63. THE ACALEPHAE. 67 colored fluid and colored corpuscles; and these corpuscles are not found except in those vessels surrounding the aquiferous canals. : There is no regular circulation, but the shifting motion of the blood aa and thither is due to irregular contractions of various parts of the ody. * CHAPTER VII. RESPIRATORY SYSTEM. § 63. The entire body of the Acalephae is traversed by canals which receive water from the stomach, or directly from without, and which is ejected ae openings upon the extremity of the body and on the margin of the isc. These aquiferous canals are lined witha delicate, ciliated epithelium, by means of which accidental particles of food or feces are quickly removed. They have been regarded both as digestive and as sanguineous organs. But that they are respiratory organs is highly probable, not only from their structure, — the cilia producing a constant renewal of water,—but also from the fact that they are surrounded by real sanguineous vessels. This aqueous circulation is oscillatory from one side of the body to the other, being interrupted only by those contractions of the body which occur when fresh water passes from the stomach into the canals.” 1 These new details upon the sanguineous system of the Acalephae are due to Will (Hore tergest. p. 34, and Froriep’s neue Not. No. 599, 1843, p. 66). In Beroé, he has been able to clearly distin- guish the sides of these vessels from those of the aquiferous canals contained in their interior, for oe first are covered with numerous red pigment cells. The blood of this animal has a greenish hue, and contains spherical or slightly elongated red corpus- cles, with large nuclei. But, beside these, Wild has found in Cydippe other nucleated cells of a green- ish color. In Polywxenia, there is no sanguineous system separate from the aquiferous canals, which, in Cytaeis and Geryonia are quite surrounded by them. ‘he vessels of Cephea contain brown cor- puscles ; and W7// has concluded that the reddish threads found along the aquiferous canals of this animal, and which Ekrenberg (Abhandl. d. Berl. Akad. 1835, p. 195, Taf. VI. fig. 3, $, and Miller’s Arch. 1834, p. 568) has taken for striated muscles, are really blood-vessels. Profound researches must decide the real relations of the aquiferous canals to the sanguineous system filled with a violet liquid of Velelia, as described by Costa (Ann. d. Sc. Nat. XVI. p. 188, Pl. XIII. fig. 3). It should be mentioned that the blood-system of the Acalephae, * (§ 62, note 1.] A true circulatory system has not been observed also by Dana (Struct. and Class. of Zoophytes, 1846, p. 12), by Forbes (Brit. Naked-eyed Medusae, 1848, p. 6), by Agassiz (Contributions to the Nat. Hist. of the Acalephae of North America, Mem. Amer. Acad. Boston, 1850, p. 260), and by Busch (Beobacht. tib. Anat. which Will has described with so much positive- ness, is not verified either by Bergmann or Frey and Leuckart (Beitr. p. 38), after numerous spe- cial researches.* 1 If, and especially with the Discophora, these canals have been taken for digestive tubes, it is because fzeces and particles of food have been here found, and which have been ejected through the openings on the borders of the body. But the real function of these openings is to discharge the water unfit for respiration; and it is only during the in- gestion of this liquid that these foreign particles are thus introduced. This communication between the respiratory and digestive systems reminds one of the Polyps, where (as in the Anthozoa) the open- ings in the stomach allow its contents to pass into the cavity of the body, which last may be likened to the aquiferous system. On the other hand, the opinion that these canals are blood-vessels would be supported by the Ctenophora, since here they are filled with a red liquid; but, according to Will (Hore tergest. p. 34), this liquid is not in these canals, but in proper blood-vessels surrounding them. He denies, also, that these blood-vessels of the Ctenophora open upon the surface of. the body, or that the blood escapes outward mixed with faeces. u. Entwick. einiger wirbellosen Seethiere, 1851, p. 13). It may, therefore, be concluded that these animals have no system of this kind, and especially so as Agassiz failed to notice it after the most inti- mate research upon the Beréid Medusae (loc. cit. p. 313), which were the objects of Wiil’s study. — ir 68 THE ACALEPHAE. § 64. § 64. With the Ctenophora, this respiratory system consists of an infundibuli- form cavity, communicating with the stomach by two orifices, situated at its base and surrounded by sphincters. Numerous aquiferous canals pass out of this cavity, traverse the body in a longitudinal direction, and finally anastomose with an annular vessel) surrounding the mouth; but, beside these, there are two short canals which pass directly to the posterior extremity of the body, where they open externally. With Eucharis and Cydippe, these canals are differently distributed ; thus, two go to the tentacles, two to the sides of the stomach, and four to the sides of the body. The same is true with Beroé, excepting that those to the tentacles are wanting. The lateral canals divide, at a short distance from the cavity, into as many branches as there are sides: With Cydippe, the excretory canals are simple; with Ewcharis they are provided with vibratile lamellae, and with Beroé with branching appendages.” With the Discophora, numerous aquiferous canals pass from the stomach or its appendages, traverse the disc in a radiating mamner, sometimes bifur- cating, and terminate at the borders of the dise in an annular vessel which opens externally by numerous orifices. In Cytaeis, Geryonia and Thaumantias, there are four of these canals, arranged in a crucial manner;® and in Aegworea there are seventy-four disposed in a ray-like way. In Medusa aurita, there pass from the four folds of the stomach six- teen of these canals, eight of which are simple, and eight bifurcating numerously before reaching the marginal vessel of the dise.® With Sthe- nonia and Aurelia” they are very numerous and widely branched. With Medusa aurita, the terminal openings of the annular vessel are eight, and regularly alternate with the organs of hearing there situated. But in Cephea these openings are said to be directly beneath these last- named organs.” With the Siphonophora, an aqueous system has not yet been well made out. There is, however, with some, an elongated cavity which is perhaps respiratory, and which, in some species, opens into the stomach, and in others directly upon the outer surface. © 1 Will (Hore tergest. p. 30, Taf. I.) has made very minute researches upon the aquiferous sys- tem of Eucharis, Cydippe and Beroé. That of Beroé ovatus, Forskalii, and of Lesueuria vi- trea, has been carefully described and figured by Milne Edwards as a circulatory system (Ann. d. Sc. Nat. XIII. p. 320; XVI. p. 203, 213, Pl. It.-VI.). 2 Will, loo. cit. Taf. IL. fig. 5, 7, 8, 14, 16. 8 Miine Edwards, Ann. d. Sc. Nat. XVI. p. 197, Pl. TE. fig. 1: 4 Rosenthal, Zeitsch. f. Physiol. I. Hft. 2, Taf, XI. ; also, Ehrenberg, Abhandl. d. Berl. Akad. 1835, Taf. L. bis. ILI. 5 Eschscholiz, loc. cit. Taf. [V.; also Brandt, Mém. del’Acad. d. Sc. de St. Petersburg, IV. 1838, Pl. 1X. X. XI. 6 Ehrenberg, Mniller’s Arch. 1834, p. 566; also, Abhandl. &c. loc. cit. p. 188, Taf. I. fig. 1, w. and Taf. IV. fig. 2, z. 7 Will, loc. cit. p. 60. 8 In Diphyes, this canal terminates in this way by an oval dilatation, lined with ciliated epithelium, and has perhaps properly been regarded by Will (loc. cit. p. 78, Taf. IL. fig. 22, a.) as a respiratory organ. A similar cavity, with a coecal appendage, is found in Ersaea (Will, loc. cit. p. 81, Taf. II. fig. 27-31, d.e.). If the arms provided with open- ings, of the Physophorae, are really stomachs, then the cavity beneath them, which has a canal passing along the axis of the animal, should be taken as belonging to the aquiferous system, for it receives water by an opening at the base of the anus. This same opening has been taken for a mouth by Philippi (Miuller’s Arch. 1843, p. 63, Taf. V. fig. 10). According to Lesson (Duper- rey, Voyage. loc. cit. No. 6, fig. B.), there is be- tween the suckers of Veded/a an orifice which leads from before backward into a large branching canal. This structure, hitherto regarded as a digestive $$ 65, 66. THE ACALEPHAE. 69 CHAPTER VIIL a SECRETION. § 65. The air-cavity of certain Siphonophora, which is surrounded by a dou- ble membrane, ought probably to be regarded as an organ of secretion ; for, according to many naturalists, the air contained could not have been de- rived from without, and consequently was secreted by the sides of the internal membrane.” CH AP'PH BR, TX. ORGANS OF GENERATION. § 66. Reproduction by fissuration and gemmation with the Acalephae has been observed only in the youngest states of certain Medusae.” But repro- cavity, belongs probably to the aquiferous system. That which in Porpita has been taken for a mouth, belongs probably, also, to the same system. I would not, however, deny that another significa- tion may be given to the so-called respiratory and digestive organs of the Siphonophora. If one prefers, with Philippi, to regard the open- ing between the tentacles of Physophora, Velella and Porpita, as a mouth, then the cavity of these tentacles should belong to the aquiferous system. Moreover, these tentacles, as to their form and mo- bility, remind one of the pedicles of the Echino- = 3 but it is remarkable that they can absorb ood. Sars (Faun. littoral. Norveg. p. 34, 42, Tab. VI. fig. 3, gg. and Tab. VII. fig. 3, e.) has observed in the interior of the cartilaginous, natatory pieces of the Physophoridae and Diphyidae, aquiferous canals which are probably of a respiratory nature. Hollard, likewise, regards the hollow and tubuli- form tentacles of Veled/a as aquiferous tubes, and in this way, as the tentacular feet of the Echino- derms, includes them in the aquiferous system. See Ann. d. Sc. Nat. IIT. 1845, p. 250. 1 Many naturalists entirely deny the presence of openings in these aérial cavities, and do not admit that they are filled with gas. Thus Philippi (Miller’s Arch. 1843, p. 63) affirms to have found neither external opening nor air in the pouch at the end of the longitudinal canal of Physophora tetrasticha. Olfers (Abhandl. d. Berl. Akad. 1831, p. 165) has not been able to find in Physadia the opening of the internal sac, said to be near the one of the external sac. In fact, Bennett (Proc. Zool. Soc. London, 1837, p. 48; and Wiegmann’s Arch. 1838, II. p. 332), with the same species, * [§ 66, note 1.] See also Huxley (Ann. Nat. Hist. VI. p. 394), who has described the reproduc- tive processes of the Diphyidae, and shown that has not seen an opening of this cavity, and was unable to force air from it. Future researches must determine if these pouches have not a respir- atory function. 1 See, upon this subject, the Embryology of these animals, below. It is not yet demonstrated that adult Acalephae reproduce by fissuration; and although Mertens (Mém. d. l’Acad. de St. Peters- burg, I. p. 494, Pl. I. fig. 2-4, and p. 527) has observed detached corpuscles from the body of Cestum and Cydippe swim freely about, and rap- idly enlarge, yet his observations are here lim- ited. In the same way, Will (Hore tergest. p. 42) has seen analogous bodies detached from Eucharis, and has found in the water others supposed to be- long to the Ctenophora, but has not traced their further condition. Propagation by buds has also been found with the Acalephs, through the excellent researches of Sars (Fauna littoral. Norveg. p. 11, Tab. IV. fig. 8-12), for this observer has seen on the external surface of the tubuliform stomach of Cytaezs octo- punctata, and upon the four ovaries of Thauman- tias multicerrata, small campanuliform Acalephs resembling their parent, in the process of develop- ment, and which were finally detached. In the genus Agalmopsis which is allied to Agalma, Sars has observed (Ibid. p. 38, Tab. VI. fig. 14-17) campanuliform bodies sprout out between the pre- hensile filaments and the tubuliform stomach, and which were finally detached, swimming freely like the Discophora. According to Sars, also (Ibid. p. 43, Tab. VII. fig. 11, b. 18, b. and 14), there is, likewise, an analogous mode of propagation with Diphyes* they multiply by gemmation as well as by ova. See, also, MidZer’s Arch. 1851, p. 380, Taf. XVI. —Eb. 70 THE ACALEPHAE. $$ 67, 68. duction by eggs, and consequently by the means of proper genital organs, has been observed in all the families. With the Ctenophora,” both sexes are combind in the same individual ; but with the Discophora, the individuals are of a. sex alone. ih The eggs are spherical, .. " ~rrounded by an exceedingly thin envelope. The vitellus is of a whitish violet or ycllow color, and contains a germina- tive vesicle, and germinative dot. The spermatic particles, which have generally the form of Cercaria (that is, a head anda filiform tail), are very active, and suffer no change in water.© In some Siphonophora, they appear to have a linear form, and attain a very great size. § 68. The genital organs are not developed except at the epoch of procrea- tion, and this period is very brief. On this account, their existence has often v...--'y escaped the notice of observers. The male and female organs so closely resemble each other, as to color, form and position, that they are easily confounded, They consist either of elongated pouches, or of riband-like bands, which are situated in different parts of the body. In the first case, the sperm and eggs escape through particular excretory canals; in the second, they escape directly outwards from the ovaries or testicles, or pass first through large cavities which com- municate externally. As they have no copulatory organs, the water is the medium of fecunda- tion. In this way the unaffected spermatic particles are brought in direct contact with the eggs. 2 Will, Froriep’s neue Not. No. 599, p. 66. 3 Siebold, Froriep’s neue Not. No. 1081, 1836, . oo." 1 Wagner (Prodrom. loc. cit. Taf. I. fig. 2; and Icon. zoot. Tab. XX XIII. fig. 15-17) and Szebold (Beitrage z. Naturgesch. wirbelloser Thiere. loc. cit. Taf. I. fig. A. B.) have figured the eggs of Cy- anea pelagia, and of a Medusa. 2 The spermatic particles of Eucharis and Be- roé consist of a round body, having a delicate and very movable tail (Will, loc. cit. Taf. I. fig. 6, 24). In Cydippe they are similar (Krohn, Froriep’s neue Not. No. 356, 1841, p. 52). This is likewise true of those of the Discophora; see Siebold, Beitrage loc. cit. Taf. L. fig. ec. (Medusa); Kélli- ker, Beitrage loc. cit. Taf. I. fig. 8, 9, 10; and Miine Edwards, Ann. d. Sc. Nat. XVI. Pl. I. fig. 1, d. (Rhizostomum, Chrysaora and Aequored) ; * (§ 66, note 3.) Reproduction by fissuration has been observed with the Discophora by Kéllé ker (Siebold and Kélliker’s Zeitsch. IV. p. 325) ; he witnessed this phenomena with Stomobrachium mirabile. It does not appear, however, that he has observed this process with adult forms ; for he remarks that there is reason to believe that this Stomobrachium is only a young, imperfect form of his Mesonema coerulescens. — Ep. + [§ 67, note 2.] The spermatic particles of the Acalephae have invariably, I think, a cercaria- Wagner, Icon. zoot. Tab. XXXIII. fig. 20, and Will, Hore tergest. Tab. IL. fig. 12 (Pelagia and Geryonia). r the spermatic particles of the Discophora, set *4lliker in the Neue schweiz. Denkschr. VII. p. =. Taf. IL. fig. 18 (Cassiopeia). t 3 It may be that the stout linear and active bodies, seen by Wid (loc. cit. p. 78, $1, Taf. II. fig. 26) in the respiratory cavity, the stomach and the general cavity of the body of Diphyes and Ersaea, and which he was inclined to regard as Entozoa are the spermatic particles of these animals, since they quite resemble those of Aleyonedlla and Cris- tatella. According to Sars (Faun. littor. &c. p. 38), the spermatic particles of Agalmopsis have a cerca- ria-form. { form, like those of the Polyps, and like which, also, they are developed in special daughter-cells. — Ep. t [§ 67, note 3.] These bodies mentioned by Will as spermatic particles have since been exam- ined by Hualey (loc. cit-), who thinks they are not of this nature, a view which is otherwise probable from the fact that he found no male generative sacs, and also because, as I have shown (see my note after § 46, note 5), these particles with Alcyonella have a cercaria-form. — Ep. $ 69. THE ACALEPHAE. 71 § 69. The position of the sexual organs varies in the different orders, in the following manner : 1. With the Ctenophora, which are hermaphrodites, they are situated along the sides, under the form of elongated utricles, the testicles being on one side and the ovaries on the other. They have a nodulated appear- ance, and from the lower part of each passes off an excretory duct, which runs toward the mouth, but the terminal opening of which has not yet been well made out. 2. With many Discophora, these organs are arranged like rays, passing from the centre to the border of the disc. In Oceania, Cytaeis, Geryonia and Thaumantias, the four saccular ovaries or testicles form at the centre of the disc a cross, which is traversed by four aquiferous canals.° Their excretory ducts pass towards the base of the stomach, but their terminal openings are not distinct. In the dise of Aeguorea violacea, seventy-four ray-like bands are spread out, and the free plicated borders of these hang beneath the inferior surface of the disc, thus permitting the free escape of the eggs and sperm into the water.” 3. Another group of the Discophora have at the base of their tentacles four large openings, which lead into as many cavities in the disc.” At the base of these cavities, which formerly were regarded as respiratory organs, the genital organs are situated in the form of plicated bands. These as four bands (testicles or ovaries) are bent either into an angle or the arc of a cir- cle, forming sometimes a star with four rays, and sometimes a four-lobed rosette.” If these cavities increase in number, the genital organs increase in the same proportion.© The border of these organs is generally pro- vided with numerous tentacles which project into the cavity. In the riband- like testicles numerous small sacs are observed; each one of these opens separately into the genital cavity, while the eggs, on the contrary, are sep- arated from the similarly-formed ovary only by a gradual constriction of the latter. 4, With the >iphonophora, all the relations of these genital organs still require much investigation. With the Diphyidae, they consist of sacs communicat’ 1 Will, Horae tergest. p. 38, Taf. I. fig. 22, 23. 2 Wagner, Icones. zoot. Tab. XXXIII. fig. 26, a.a.; Will, loc. cit. Taf. Il. fig. 5, 7, 8, 14, 16; Blainville, Manuel d’Actinol. 183.. “ “YX VIT. fig. 3: and Sars, Beskrivelser loc. cit. x. 1. 12, 13. 3 Will, loc. cit. p. 71. 4 Milne Edwards, Ann. d. 8c. Nat. XVI. p. 198, Pl. I. fig. 1, a. b. 5 Gaede, Beitrige loc. cit. Taf. I. fig. 1, c. (Me- dusa) ; and Lesson in Duperrey, Voyage loc. cit. No. 12, 13 (Chrysaora). 6 Rhizostomum. 7 Chrysaora, Medusa, Pelagia and Aurelia. See Ehrenberg, Abhandl. d. Berl. Akad. 1835, Taf. I. fig. 1; Wagner, Icon. zoot. Tab. XX XIII. fig. 1; and Brandt, Mém. de P Acad. de St. Peters- burg, IV. Pl. 1X. X. With the male and the female Cephea, I have found the testicles and the ovaries disposed exactly as with the 2. 8 In Cassiopea, these organs aie .gutin number. 9 Medusa and Pelagia; see Ehrenberg, loc. 445° g with the general cavity of the body.“ During the epoch cit. Taf. VII.; and Wagner, Icon. zoot. Tab. XXXIII. fig. 13. 10 Siebold, Beitraige loc. cit. Taf. I. fig. 20, 23 ; and Kélliker, Beitrige loc. cit. p. 40. 1! In Diphyes and Ersaea, a sac filled with cells opens into the general cavity of the body, and communicates beside with the stomachs and respi- ratory cavities. Wz/l (Horae tergest. p. 78, 81, Taf. IT. fig. 23, c.) regards this sac as a sexual organ; and Meyen (Nov. Act. physico-med. XVI. Suppl. 1, 1854, p. 214, Tab. XXXVI. fig. 2, h. and fig. 6, 7) asserts to have seen eggs init. Accord- ing to Philippi (Miiller’s Arch. 1843, p. 63, Taf. V. fig. 10, a. b.), the grape-like clustered genital organs, with Physophora, are situated between the prehensile organs ; the smallest containing in each lobule six to ten eggs, and the largest a granular liquid (Sperm ?). Hollard (Ann. d. Sc. Nat. IIT. 124" — °°" Pi. TY. bis. fig. 33, 84) has found botiy o.... .. s of ovaries at : ise of the tubuliform tentacles (stomachs). pole i. p. 37, Pl. V.) bas also $ 70. of procreation, the females of some Discophora are easily distinguished from the males by the numerous pouches of their tentacles, and in which eggs and newly-hatched young are carried for a short time.“ 72 THE ACALEPHAE. § 70. As yet, the development of a few only of the Acalephae has been traced. Tt is attended by a remarkable metamorphosis. After the usual segmentation of the vitellus, ovoid embryos;resembling infusoria are developed; these turn freely on their axis, and swim about in the water by means of ciliated epithelium.” Shortly after, they become attached by the anterior extremity to some object. Upon the opposite free extremity tentacles appear, and between them the mouth. The animal has then the form of a Polyp.” It is during this period that the young ani- mal reproduces by gemmation,® and sometimes by transverse /isswration. This last mode occurs in the following remarkable manner : The polyp-like animal increases in length, and its body divides trans- versely into many segments. y g Around each of these segments eight bifid processes are developed; after this, each segment is successively separated from before to behind, and they float about for a time as eight-rayed Aca- lephae, but soon attain, however, their adult condition. ® seen genital organs of the same form between the tentacles of Agal/mopsis ; but he found at the same time (loc. cit. p.38, 45), inthe campanuliform individ- uals produced from buds, testicles with 4galmopsis, and ovaries with Diphyes. It may therefore be justly supposed that these various Siphonophora are compound, sexless individuals, which, like the Hydrina and Sertularina, reproduce by alternation of generation,—that is, by buds, — individuals having sex. 12 Medusa aurita and Cyanea capillata; see Ehrenberg, Abhandl. &c. loc. cit. Taf. ITT. fig. 1, 2, Taf. VIL. fig. 1; also, Sars in Wiegmann’s Arch. 1841, I. p. 19. 1 The development and metamorphosis of Me- dusa aurita and of Cyanea capillata have been observed by Siebold (Beitrage loc. cit. p. 21, Taf. I. Il. ; and Froriep’s neue Not. No. 166, 1838, p. 177); and by Sars (Wiegmann’s Arch. 1841, I. p. 19, Taf. 1.-[V.). In the first stage of development (see Ehrenberg, Abhandl. &e. loc. cit. Taf. VIII. fig. 15-18 ; also, Siebold, Beitrage loc. cit. Taf. I. fig. 17-19; and Sars, Wiegmann’s Arch. loc. cit. Taf. 1. fig. 1-6), these infusoria-like Medusae have been regarded by Baer as the larve (Meckel’s Deutsches Arch. VIII. 1823, p. 389). 2 Siebold, Beitrage loc. cit. p. 29, Taf. I. fig. 25-33, Taf. Il. fig. 34; and Sars, Wiegmann’s Arch. loc. cit. Taf. I. fig. 7-31. During my last visit at Trieste (autumn of 1847), I convinced myself that the young of Cephea Wagneri are developed wholly like those of Medusae, by passing from infusoria-like forms to polypoid young ani- mals.* 8 The reproduction of the polyp-form Medusae, by buds has been observed by Sars in Cyanea * [§ 70, note 2.] See, also, for recent researches on the development of Cephea, Ecker, Bericht tib. die Verhandl. d. naturf. Gesellsch. in Basel. VIII. 1849, p. 51; Busch, Beobachtungen tb. die Anat. &e. Berlin, 1851, p. 80; and Frantzius, in Sie- capillata. He has also seen them develop pedi- cles from the end of which new individuals would appear, which resembled Polyps. See Wiegmann’s Arch. loc. cit. p. 26, Taf. I. fig. 37, 41, 42, 58, 39, 40. 4 These young Medusae, whilst composed of rings, have been taken for a new genus (Scyphistoma) of Polyps by Sars (Isis. 1833, p. 222, Taf. X. fig. 2). Steenstrup (Ueber d. Generationswechsel, p. 17) has regarded them as nurses of the Medusae. At a latter period, when the rings have been separated and have acquired the bifid prolongations, Sars (Isis. 1883, p. 224, Taf. X. fig. 4; and Beskrivel- ser, &c., p. 16, Pl. IIL.) has described them as a new species of Medusae (Strobila octoradiata). But lately he has perceived that they are the young of Medusa aurita (Wiegmann’s Arch. 1837, I. p. 406) ; it did not occur to him, however, that these young constitute, very probably, the genus Ephyra of Eschscholtz (see Wiegmann’s Arch. 1841, Th. I. p. 10). It will probably be discovered that many small campanulate or discoid Medusae are only the young of other Acalephae; for it is very likely that they all undergo a similar metamorpho- sis. It may also prove that many naked Polyps are only transitionary forms of known species of Acalephae. In this connection the observation of Dujardin (Comp. rend. 1845, p. 1132) deserves the attention of naturalists. In tracing the deyel- opment of one of the Discophora allied to Oceania, he observed that this animal in its early condition separated from a corallum resembling that of Syn- coryne, and was of a form quite like an Eleuthe- ria. However various these developing forms may be, that one must be regarded as the real one which exists during the development of the testi- cles and ovaries. bold and Kélliker’s Zeitsch. f. Zool. IV. p. 118, June, 1852. — Ep. 7 [§ 70, note 4.] In regard to the development of the Acalephae, it may be mentioned that recent researches, few as they are, have verified some § 70. of the hypotheses suggested in the above note. Hitherto there has been much confusion on this subject, from the want of complete series of obser- vations ; even now the whole class can be regarded only in a somewhat transitionary state, in a zoological point of view. Many genera which have hitherto been regarded good and permanent will no doubt, as Stebold has remarked, prove te be only unde- veloped forms of well-known species. As already stated, Agassiz regards the Hydroid Polypias true Acalephae, and the analogy which exists between fi THE ACALEPHAE. HO fo the embryos of Medusae and Polypi may be the foundation of many other important changes. At present, however, broad generalizations must be deferred until we have extensive and serial re- searches in the embryology of these animals. For separate details on the development of some forms, see Busch, loc. cit. (Sarsia, Lizzia, Cephea, Eu- doxia, Diphyes); Hualey, loc. cit. (Diphyidae, Physophoridae); Agassiz and Desor, loc. cit. (Medusidae).— Ep. BOOK FOURTH, ECHINODERMATA. CLASSIFICATION. 6 ike Tae Ecutnoprrms have a more or less coriaceous envelope, filled with cal- careous, reticulated corpuscles. These last are sometimes so numerous that they form a real shell, composed of plates, movable, or tightly bound together. In the ray-like, symmetrically-arranged systems of organs, the quinquenary number prevails. In many species the digestive canal is asymmetrical. All are marine, and most of them move by means of particular, erectile suckers. Others progress by vermiform motions, and some swim freely by moving their rays like oars. Only a few are stationary. All are without copulatory organs. ORDER I. CRINOIDEA. The calcareous shell, composed of movable pieces, forms a true cutane- ous skeleton. The body is ray-like; the digestive canal, asymmetrical. Famity: Encrinmae. Genus: Pentacrinus. Famity : ComMatTuLinag. Genus: Comatala. ORDER II. ASTEROIDEA. The calcareous shell, composed of movable pieces, forms an internal skel- eton. The cutaneous covering is sometimes coriaceous, and sometimes cal- careous. The body is ray-like, and the digestive canal symmetrical. Famity : Opnturtar. Genera: These details are supported by Valentin (loc. cit. p. 95), who has already added much to the labors of Tiedemann and Delle Chiaje upon the sanguineous system of Echinus, although, like his predecessors, he has been deceived as to its con- nections. The received opinions upon the circulation of these Echinoderms are, therefore, hypothetical. The nature of the, five glandular organs, which Val- entin has seen communicate with one of the two vascular rings situated upon the lantern, is very problematical (Monogr. &c. p. 95, Pl. VII. fig. 119, i. 120). 6 See Tiedemann, loc. cit. p. 15. The sanguine- ous system of Synapta Duvernaea, as described by Quatrefages (loc. cit. p. 58), corresponds, properly, to the aquiferous system of Holothuria, which Ziedemann also has taken for a special Sanguineous system of the skin and ambulacra. Hereafter we shall notice further both of these sys- tems.* 7 For the sanguineous vascular system of Sipun- culus, and Echiurus, see Grube and Krohn (Mil der’s Arch. 1837, p. 248; 1839, p. 350), also Forbes and Goodsir (Froriep’s neue Not. No. 392, loc. cit.). The vascular trunk embraces there the nerve so closely, that care is necessary not to overlook one, or confound both together. Quatrefages has found in the anterior part of the body of Echiurus Gaertneri three heart- shaped swellings of the blood system, namely, a ventral heart upon the ventralyvessel, a dorsal heart upon the dorsal vessel, and a mesenteric heart situated beneath the digestive tube. This last communicates with the ventral heart by a flexuous vascular canal, and with the dorsal vessel by a small vascular ring ; see Ann. d. Sc. Nat. loc. cit. p. 324, Pl. VI. fig. 4. tion above quoted as to the general distribution of the vessels, and especially as to the presence of a splanchnic system, which, as is well known, Qua- trefages has supposed to be wanting. — Ep. THE ECHINODERMATA. 91 §§ 89, 90. * CHAPTER: V-11. RESPIRATORY SYSTEM. , § 89. The respiration of the Echinoderms is performed in various ways. These are: 1. By exclusively respiratory branchiae. 2. By organs serving at the same time other functions. 38. By means of water passing through the openings of the skin into the cavity of the body, and aérating the blood through the capillary vessels of the viscera. With the Asteroidea, Synaptinae, Sipunculidae and Hchiuridae, every individual has always two of these modes of respiration, and sometimes all three, as with the Kchinidae and Holothurinae. § 90. I. Organs which are exclusively respiratory are found in the Kechi- nidae, Holothurinae, and Hchiuridae. They consist of external branchiae in the first, and internal in the last two. The external branchiae of the Hchinidae are situated upon the soft membrane of the mouth, being formed of five pairs of arborescent, hollow lobules.” They are contractile, but cannot be retracted within the body. They are covered both internally and externally with ciliated epithelium. The cavity of each communicates with that of the body by a large ori- fice situated on the internal surface of the oral membrane.” By this means they are bathed with water upon both of their surfaces. Their walls contain a coarsely reticulated calcareous skeleton,” and without doubt, also a capillary net-work belonging to the branchial vessels. The internal branchiae of the Holothurinae arise as two tubes from the cloaca of the intestinal canal, and send off, through the whole cavity of the body, numerous coecal branches. In Holothuria tubulosa, one of these tubes is closely connected with the turns of the intestine, while the other is attached to the inner walls of the body. With the first, espe- cially, may be perceived the ramifications of the branchial vessels. They are also covered with ciliated epithelium, and their contractile and expan- 1 The ramified organs of the Echinidae, already known by Tiedemann (loc. cit. p 78, Taf. X. fig. 5, d.d.) and Delle Chiaje (loc. cit. II. p. 338), haye been more exactly described by Valentin (Monogr. &c. p. 82, Pl. IV. fig. 57; Pl. VIII. fig. 42), and by Erdl (Wiegmann’s Arch. 1842, I. p. 59, Taf. Lf. fig. 12, 13). 2 Valentin, loc. cit. Pl. VIL. fig. 135, 1. 8 Valentin, loc. cit. fig. 143 ; and Erdi, loc. cit. fig. 13.* 4The branchiae of Holothuria tubulosa have *[§ 90, note 3.] See, in this connection, Miller (Arch. 1850, p. 122), who has confirmed Valen- been very well described by Tiedemann (loc. cit. p. 11, Taf. I. or Wagner Icon. zoot. Tab. XXXII. fig. 9), and by Delle Chiaje ‘(loc. cit. Tay. VIII. [X.). See also Atlas Zool. du Voyage de l’Astrolabe. Zoophytes, Pl. VIL. fig. 2, 9, p. (Holothuria ananas) and P|. VII: fig. 3, e (Clad- olabes spinosus). Pentacta doliolum has simi- lar organs. According to Cuvier (Anat. Comp. VII. 1840, p. 536) there is only a single branchia in the other remaining Holothurinae. tin’s observations as to the structure of the exter- nal gills. — Ep. 92 THE ECHINODERMATA. $$ 91, 92. sive power, united with the action of the cloaca, enables them to receive into and expel from their interior the water of the sea. The internal branchie of the Echiuridae consist of branchless tubes. In Echiurus vulgaris, the two branchiz, which are very movable and open into a kind of cloaca, have, on their exterior, infundibuliform, ciliated pro- tuberances; and to each of these there is internally a corresponding cili- ated sac, capable of being inverted. The very bright-red, vascular net- work which is spread over these branchiae, communicates with the great ventral vessel at the posterior extremity. § 91. II. Among the organs which are not exclusively respiratory, are the ambulacra of the Echinodermata pedata, and the oral tentacles of the Ho- lothurioidea and Sipunculidae, — organs which are used also for prehension and locomotion. These ambulacra and tentacles have always a cavity which communicates directly with the proper vascular, aquiferous system. Their whole interior is covered throughout with ciliated epithelium. This aquiferous system has, until recently, been taken by anatomists as a special vascular one, or confounded with it. Its water serves partly to distend the ambulacra and tentacles, as shown above () 77), and partly for respiration, which is performed by the vesicles over which ramify the branchial vessels. These vesicles are therefore like internal branchie, their vessels being bathed by the water of the sacs, and that of the cavity of the body. Usually this system consists of a ring situated between the vascular rays of the mouth, which sends canals to the oral tentacles and to the sides of the body. These canals always pass along by the rows of ambulacral vesicles, with which they communicate by lateral branches, § 92. In the Echinodermata pedata, this aquiferous system has the following modifications : In the Crinoidea, and Ophiuridae,” only traces of it have been found. In the first, there is an apparently aquiferous canal for the tentacles, situated directly under their furrow. This may be regarded as forming a part of such a system. In Pentacrinus, it is simple, but in Comatula, it is divided at several points by simple septa. In the Asteroidae, this system is highly developed, the central ring being provided with pediculated and often elongated vesicles. The main 5 There is found, but inconstantly, it would appear, upon the trunk of the branchiz of some Holothurinae particular pedunculated coeca, which in Bohadschia marmorata have been regarded as urinary organs by Jaeger (De Holothuriis, Xc., Tab. III. fig. 9, g.). But they require further investigation.* 6 Forbes and Goodsir (Froriep’s neue Not. No. 392, p. 277, fig. 12, e. — 19). 1 From the figures of Delle Chiaje (loc cit. Tav. *[§ 90, note 5.] For many new details upon the respiratory system of the Holothurioidea, see XXI. fig. 17) it would appear that Ophiurus has an aquiferous system. 2 Miller, Abhandl. d. Berl. Akad. 1841, p. 234. 3 These pyriform vesicular appendages are al- ways situated between the principal vessels of the rays, varying both as to number and volume, and being sometimes entirely wanting. Astropecten bispinosus has only five; Asteriscus verrucu- latus, Astropecten pentacanthus, and Astera- canthion glacialis, have ten, in pairs. In this Miller, Arch. 1850, p. 129-155 (Synapta, Chir- odota, and Molpadia).— Ep. THE ECHINODERMATA. 93 § 92. trunks from this oral ring pass along the furrows of the rays close to their external surface. The ambulacral vesicles into which their lateral branches open, are sometimes simple,“ or, from a kind of sulcation, have a heart-like form. In the Hchinoidea, the oral ring wants the pyriform appendages, and its main trunks pass along the internal wall of the shell. The ambulacral vesicles of the oral membrane are conical; but the others are flattened, overlap each other in a tile-like manner,” and have a distinct branchial, vascular network.® The aqueous oral ring of the Holothurinae has hollow appendages (ten- tacular vesicles) projecting into the cavity of the body.” It has also, in many species, a larger, longer, and sometimes double, coecal vessel (Am- pulla Poliana). Opposite the tentacular vesicles, the ring sends off to the oral tentacles, vessels which are often arborescent and comparable to external branchiae ;™ while, between these vesicles, arise five other vessels which descend along the internal surface of the body. As usual, they send off lateral branches to the generally very small ambulacral vesicles. In a few species only of the Synaptinae, the aquiferous ring has hollow appendages. sides of the body. do not give off lateral branches,” In the Sipunculoidea, the aquiferous system is least developed. From it pass off vessels both to the tentacles and to the As the ambulacra are here absent, the five main trunks As yet there has been found only a liquid moved by vibratile cilia in the doubly- laminated cavity of the lobulated tentacles of the Sipunculidae. With this cavity, two vesicles of Poli communicate, thus indicating the presence of an aquiferous system.” last species they are only slightly developed ; in Astropecten aurantiacus there are three to,seven vesicles, opening by a common duct into each of the five angles of the aqueous vascular ring ; see Delle Chiaje, loc. cit. IL. p. 296 ; Tiedemann, loc. cit. p. 52, Taf. VILL. ; Konrad, loc. cit. fig. 3; and Meckel, Syst. d. vergleich. Anat. V. p. 32. Here should be mentioned also the glandular corpuscles which are attached to the aqueous vascular ring, and which resemble in_some respects the glandular organs of the vascular sanguineous rings of Echi- nus, pointed out by Valentin ; see Delle Chiaje, loc. cit. If. Tav. XXI. fig. 12, 14; Tiedemann, loc. cit. Taf. VIII. 0. 0., or Wagner, Icon. zoot. Tab. XXXII. fig. 2, m. 4 Ophidiaster, Asteracanthion, Luidia; see Miller and Troschel, loc. cit. Taf. XI. fig. 4. 5 Astropecten ; see Konrad, loc. cit. fig. 4. I am not yet settled upon the question whether the aquiferous system of the Asteroidae ig filled by the extremity of the ambulacra, or by the oral ring. I have not been able to convince myself of the pres- ence of an opening at the extremity of these first. 6 Delle Chiaje (loc. cit. Tay. XXVI.) has given very detailed figures of the aquiferous system of Echinus and Spatangus ; but he has confounded it with the sanguineous vessels of the intestinal canal. 7 Valentin, Monogr. &c. Pl. CXXXIV.— CXXXVI. 8 The branchial vessels ramifying upon the flat- tened ambulacral vesicles appear to have been seen by Monro (Vergleichung des Baues und der Phy- siol. der Fische, 1787, p. 91, Taf. XXXIII. fig. 13-15 ; or Cyclopedia of Anat. and Physiol. IL. p. 35, fig. 14). Krohn (Miiller’s Arch. 1841, p. 5) has accurately described them. It is affirmed that the ambulacra of Echinus can be filled with water through an opening of the sucker at their extremity, and that it is discharged from the aquif- erous system through ten openings between the teeth ; see Tzedemann, loc. cit. p. 81; Valentin, Monogr. &c. p. 84, or Repertor. f. Anat. 1843, p. 237 ; and Monro, loc. cit. p. 92. 9 Tiedemann, loc. cit. Taf. IL. fig. 4, e. e. fig. 6, m., and Delle Chiaje, loc. cit. Tav. VIII. IX. 10 Tiedemann, loc. cit. Taf. II. fig. 4, a. a. fig. 6, g.; Delle Chiaje, loc. cit. Tav. IX. fig. 6, fi. (Holothuria tubulosa). 11 The position of the tentacular vesicle seems exactly adapted to enable them to force, during their contraction, their water into the tentacles, thus causing the prominence and development of these last. I am yet uncertain if they are not aided by the vesicles of Poli. With some Holo- thurinae, as with Cladolabes spinosus (Atlas zool. du Voyage de l’Astrolabe. Pl. VIT. fig. 3, f.), and with Pentacta doliolum according to my own observations, the aquiferous ring has only one ve- sicular appendage, and it would be questionable whether this is analogous to a tentacular vesicle, or to one of Poli. Thyone and Cuvieria have, according to Ko- ren (loc. cit. p. 20, 36, fig. 2, 11), only a single large, vesiculiform appendage upon their aqueous ring. 12 See Delle Chiaje, loc. cit. Tav. IX. fig. 6 (Holothuria tubulosa) ; but here also the aquife- rous is confounded with the sanguineous system. 13 In Chirodota Doreyana, and fusca, these hollow tentacular vesicles are very apparent; see Atlas zool. du Voyage, &c., loc. cit. Pl. VII. fig. 16, Pl. VILL. fig. 3. 14 Quatrefages, loc. cit. p. 58, Pl. IV. fig. 1, Pl. V. fig. 5. 15 That the tentacular membrane of the Sipun- culidae has the function of a branchia, is indicated 94 THE ECHINODERMATA. S$ 93, 94. § 93. IIL. In nearly all the Echinoderms, as has been seen, all the viscera are bathed with water which certainly affects their delicate blood-vessels. It is very probable that from ciliated epithelium covering the entire cavity of the body and the viscera this water circulates in a definite manner. It is rejected at last through many respiratory openings, through which also fresh water is introduced. In the Ophiuridae, there are in each inter-radial space two or four large openings of this kind, leading into the cavity of the body.” In the Asteroidae, water passes freely in and out the cavity of the body, through small contractile trachean tubes, which have been known for a long time, and which are very numerous upon the back. They are cov- ered within and without with ciliated epithelium, and have an opening at their extremity.° As yet it is unknown how the cavity of the body of the Echinoidea and Holothurioidea receives the water. Only in Synapta Duvernaea, have there been found proper respiratory openings ; these:are four or five papille, covered with cilia, concealed at the base of the oral tentacles, and connecting with the cavity of the body through a narrow canal. In the Sipunculidae, the water is received through an opening at the posterior end of the body.@* CHAP TER: VIE. ORGANS OF SECRETION. § 94. The Echinoderms appear to have special organs of secretion. In differ- ent parts of the body there are glandular organs, the real nature of which, however, has not yet been determined.” by the presence of delicate and tortuous vessels, observed by Grube (Miiller’s Arch. 137, p. 253) upon that of Sipunculus nudus. The same con- clusion might be drawn from the liquid moved by cilia observed by myself in the interior of the ten- tacular lobules of Phascolosoma granulatum. Grube (Miiller’s Arch. 1837, p. 251, Taf. XT. fig. 2, P.) has seen in Sipunculus nudus the two vesi- cles of Poli, communicating with the cavity of the tentacular membrane. 1 Miller and Troschel, loc. cit. Taf. IX. X. 2 Ehrenberg, Abhandl. d. Berl. Akad. 1835, Taf. VOT. fig. 12, e.; and Shkarpey, Cyclopedia of Anat. &c. I. p. 615, fig. 298, C. * [ End of § 93.] In Echinarachnius and Cly- peaster Agassiz has observed that trachean tubes, similar to those of the Asteroidae, perform the function of carrying the water in and out of the body. They are situated chiefly along the margin 3 Quatrefages, Ann. d. Sc. Nat. loc. cit. p. 64, PU Ve tieenlgate 4 The manner in which the water enters into the interior of the Echiuridae is not quite clear to me from the description of Forbes and Goodsir (Fro- riep’s neue Not. No. 392, p. 277). 1The attention has already been directed to these glandular organs, when speaking of the parts to which they are attached. The calcareous sac, or stony canal as now understood, of certain Aste-~ riae, can scarcely be regarded as organs of secre- tion. of the dise, emptying first into a circular tube, anal- ogous to the circular tube of the Discophora, from which extend ramifications into the main cavity of the body ; see Compt. rend. 1847. — Ep. $$ 95, 96. THE ECHINODERMATA. 95 CHAPTER IX. ORGANS OF GENERATION. § 95. Although most Echinoderms have extraordinary powers of reproduc- tion, yet this, apparently, is not for the multiplication of the individuals, for they do not reproduce either by fissuration or by buds. The Holothurioidea alone, perhaps, form the exception.® All propagate by the sexual organs of separate male and female individuals, and her- maphroditism is very rare. The eggs which are usually round, are covered by a thin chorion, and contain beside a little albumen, a variously colored vitellus with its germi- native vesicle and dot.” The sperm is always milky, and the spermatic particles which are unaffected by sea-water, are nearly always composed of a round or oval, rigid body, to which is attached a delicate, very active tail. § 96. Externally, the organs of both sexes exactly resemble each other, and especially during the interval of procreation; but at the sexual epoch they often differ in color. Their situation is very varied, and they are composed of simple or branched tubes, with proper excretory ducts. These last, however, are sometimes wanting, and then the contents of the former escape by rup- ture, and, falling into the-cavity of the body, pass out through the respira- tory openings. Here, as in the Polyps and Acalephs, the copulatory organs being absent, the water is the medium of the fecundation of the eggs, by bringing the spermatic particles in contact with them. ‘1 The Holothuria, which, when captured, dis- charge all they viscera through the mouth, can, according to Dalyell (Froriep’s neue Not. No. 331, p. 1), not only reproduce all these. but also can divide spontaneously into two or more parts, each of which becomes a complete individual. This multiplication by fissuration occurs also, perhaps, with Synapta Duvernea; see Quatrefages, loc. cit. p. 26. , 2 See the eggs of Comatula Europaea (Miil- ler, Abhandl. d. Berl. Akad. 1841, Taf. V. fig. 17), of Asteracanthion, violaceus (Wagner, Prodro- mus, &c., Tab. I. fig. 3, or Carus and Otto, Erlaute- rungstafeln, Hft. V. Taf. I. fig. 1), of Echinus livi- dus and sphaera (Valentin Monogr. &c. fig. 167, 169), of Holothuria tabulosa (Wagner, Icon. zoot. Tab. XXXII. fig. 12), and of Synapta Du- vernaea (Quatrefages, loc. cit. Pl. V. fig. 1). * [§ 95, note 3.] The spermatic particles of the Echinoderms are developed, like those of the other Radiates, in special cells, and like them also have, I think, invariably a cercaria-form. The differ- ences in the shape of the head of these particles 3 See, for the spermatic particles of Astera- canthion, Solaster, and Echinus (Kélliker, Beitrage, loc. cit. fig. 1-4, and Valentin, Monogr, &e. fig. 168), of Holothuria and Synapta (Wagner, Icon. zoot. Tab. XXXII. fig. 13, and Quatrefagzes loc. cit. Pl. V. fig. 2). Those of sim- ilar form have been seen in Comatula by Miller (Monatsbericht d. Berl. Akad. 1841, p. 189, or the Abhandl. of the same, loc. cit. p. 235). Accord- ing to Valentin (Repertorium, 1841, p. 301), those of Spatangus violaceus have an elongated body, pointed in front, with a very delicate hair-like tail. Those of Ophioderma longicauda, and Ophiothriz fragilis, according to my own obser- vation, have a round body, with an equally deli- cate hair-like tail.* are wide, and of zoological import. Thus it is sometimes round (Asterias, Urastes), sometimes pyriform (Echinocidaris), and sometimes long- conical (Medlita). — Ep. 96 $ 97. THE ECHINODERMATA. § 97. In the Crinoidea, these organs, in the form of tubes, are situated under the soft perisoma of the pinnulae, and probably are without proper excre- tory ducts. In the Ophiuridae, they consist of lobular, pedunculated sacs, which are suspended in pairs in the inter-radial spaces of the disc. These ten organs are usually deeply fissured, and the lobules thus formed appear as so many proper sacs attached to the peduncle. These last are sometimes subdivided also. Sometimes each organ, divided in its whole length into lobules, is turned in the shape of a ram’s horn.” The peduncle of these organs is directed towards the mouth, but it is yet uncertain whether their contents escape this way or fall into the cavity of the body. In the first case, the pedun- cle would be the excretory duct ;® and in the second, the eggs and sperm would escape through the respiratory openings. In the Asteroidae these organs consist of varicose lobular sacs, situated in the angles of the inter-radial spaces. In those species which are without an anus, there are no proper genital openings ; © these openings are also wanting in those Asteroidae which have an anus. In these last, the sperm and very small eggs pass into the cavity of the body, and probably have their escape through the respiratory openings.” But in some species,™ there are upon the back and near each angle of the inter-radial spaces two small approximated plates, perforated by small openings (Laminae cribrosae). ‘These are the simple openings of these organs, which here consist of multi-ramose sacs, situated all along each side of the inter-radial septa, to the common duct which opens through one of the plates. The number of these genital sacs varies widely in the different genera of the Asteroidae. In many, a single trunk of them hangs on each side of the inter-radial septa ; in others, there is a whole row of them ;“ and in others still, there are two rows attached to the dorsal surface of the cavity of the body, and extending into the rays.“ In the Echinoidea, these organs descend along the internal surface of 1 The development of the genital organs of Comatula was first observed by Dujardin, who asserts that the red vesicles situated on both sides of the tentacular furrows secrete, during the epoch of rut, a very beautifully red liquid (L’Instit. No. 119, p. 268, or Wiegmann’s Arch. 1836, IL. p. 207). Thompson has seen the eggs of Comatula escape in clusters through the openings of the pin- nulae (Edinb. New Philos. Jour. No. XX. p. 295, or Froriep’s neue Not. No. 1057, 1836, p. 4, fig. 8); while, according to Muiller, they escape by rupture (Abhandl. d. Berl. Akad. 1841, p. 254, Taf. V. fig. 17, 18). 2 Ophioderma longicauda, and Ophiolepis scolopendrica ; see Rathké, Foriep’s neue Not. No. 269, p. 65; and, Neueste Schrift. d. Natur- forsch. Gesellsch. in Danzig. III. Hft. IV. 1842, p 116, Taf. IL. fig. 3, 4. 3 Ophiocoma nigra; see Rathkeé, Schrift. &c. loc. cit. Taf. IL. fig. 5-7. 4 Ophiothriaz fragilis. 5 Rathkeé, loc. cit. 6 Miller and Troschel, loc. cit. p. 133. 7 Miller and Troschel have very interesting details upon the various arrangements of the geni- tal organs of the Asteroidae (loc. cit. p. 132). Danzig. 8 As in Astropecten and Luidia. 9 As in Ophidiaster. 10 According to Sars, the ventral surface of the disc and arms of the female Echinaster sanguin- olentus and Asteracanthion Miilleri have at cer- tain times a kind of incubating cavity, in which the eggs remain during their development. He thinks they get there from the cavity of the body, through particular openings upon the ventral surface of this last ; see Wiegmann’s Arch. 1844, I. p. 169, Taf. Wiklsfie. 12, The genital parts of Echinaster sanguinolentus have been described with much detail by Sars, Faun. littor. Norveg. p. 48. ll Asteracanthion rubens, and Solaster pap- posus ; see Miller and T'roschel, loc. cit. Taf. XII. fig. 2-4. 12 Echinaster, Astrogonium, Asteriscus, and Ctenodiscus. 13 Astropecten, Oreaster, and Culcita; see Tiedemann, loc. cit. p. 61, Taf. VIII. L. L. 14 Archaster, Chaetaster, Luidia and Ophidi- aster ; see Miller and Troschel, loc. cit. Taf. XIU. fig. 5. $ 97. THE ECHINODERMATA. 97 the shell, filling the empty spaces between the double rows of ambulacral vesicles. They consist of widely ramified, deeply interlocked coeca, having always proper excretory ducts, which open upon the genital plates of the back of the shell.“” There are here always five of these organs, and the genital plates, alternating with the ocellary ones, surround the anus.“ In some species of the Clypeastridae, and Spatangidae, there are, perhaps, only four of these organs, judging from that number of the plates.“ In the Holo- thurinae, these organs have a very different arrangement. They consist of widely-branched coeca,“® floating, as loose clusters, freely in the cavity of the body, and opening through a single common-excretory duct, situated below the osseous circle, and between the oral tentacles. The testicle, which is of a whitish color, consists of a cluster of cy lindri- eal sacs, branched and interlocked with each other.“ But the ovary is pale red, very long, branched, a little flattened, and extends even to the posterior end of the body.“ As the only exception among these animals, the Synaptinae are her- maphrodites. But it should be stated that we know of them only through Synapta Duvernaea. It is said that here the testicles and ovaries are united in one and the same organ.©? Three or four long cylindrical sacs float in the cavity of the body, and have an excretory duct which opens back of the osseous circle. At the epoch of procreation, vesicular pro- longations appear on their interior surface, in which are formed spermatic particles. ous mass, in which appear eggs.“ The spaces between these prolongations are filled by a pultace- In the Sipunculidae, and Hchiuridae, there are only two or four simple cylindrical contractile pouches attached to the ventral wail. It is yet undetermined whether their contents escape by rupture, or through special ines, @) openings. 15 The separate sexes of Echinus were first shown by Peters; see Miiller’s Arch. 1840, p. 143. 16 See Tiedemann, loc. cit. p. 85, Taf. X. fig. 1, 4,8; and especially YVulentin, Monogr. &c. p. 103, Pl. VILLI. W With Echinanthus, Mellita, Rotula, Scutella (see Agassiz. Monogr. des Scutelles), and Spa- tangus arcuarius, and ovatus, I can count only four genital plates, while in Encope, and Clypeas- ter, I find five; yet Valentin (Repertorium, 1840, p. 301) expressly speaks of five genital organs in Spatangus violaceus. 18 Wagner and Valentin were the first who noticed the sexual differences of Holothuria tubu- losa; see Froriep’s neue Not. No. 249, p. 99. 19 See Wagner, Icon. zoot. Tab. XXXII. fig. 11 (Holothuria tubulosa). J have already remarked (§ 86), that the white cylindrical pedicelle, taken by some zootomists as testicles (Delle Chiaje, loc. cit. I. p. 97, Tav. VIII. fig. 1. 0.), are distinct from the genital organs, and communicate directly with the intestinal canal. 20 See the Catalogue of the Physiol. Series, &c., loc. cit. [V. Pl. XLIX. fig. 1. c. (Holothuria tub- ulosa). 21 Quatrefages, Ann. d. Sc. Nat. loc. cit. p. 66, Pl. IV. fig. 1, q. Pl. V. fig. 1. 22 This deep confusion of the organs of two sexes is something so remarkable, that one cannot but believe that Quatrefages has here taken the parent sperm cells for the eggs. 23 In Sipunculus, and Phascolosoma, there is observed on each side, a little front of the anus, a sac attached to the side of the body (see Delle Chiaje, loc, cit. Tav. I. fig. 5, s.s. and Grube, Moiller’s Archiv. 1837, Taf. XI. fig. 1. v°). These have been regarded as genitalorgans. In Sipunculus nudus, Grube has found eggs not only in these sacs, but in the cavity of the body also. It may, therefore, be questioned if the eges escape from the sacs into the cavity of the body, whence they are expelled through an opening at its posterior extremity, or if they are accidentally introduced from without with the water, during respiration. In this last case, these sacs should have excretory ducts; and there are, indeed, in Sipunculus nudus, two external fossee opposite the point of insertion of the saées (see Delle Chiaje, loc. cit. Tay. I. fig. 2, f.), and in which, it is said, there are two very small openings. this canal is simple, straight, and ends posteriorly in an anus.” In many Trematodes, the intestinal tubes have in all their course simple or ramified caeca, and in some, these caeca are so fully developed that the intestinal canal appears to fill the whole body.® ‘The intestinal walls here are very thin, but this does not prevent peristaltic and anti-peristaltic movements, by which their contents move backwards and forwards, and are often rejected through the mouth.” § 108. In the Nematodes, and Gordiacei, the intestinal canal passes straight from the mouth which is at the anterior extremity, through the cavity of the body to the anus, which, in the first, opens front of the caudal extremity.” In very many Nematodes, the mouth has nodosities and swellings, but it is seldom that its cavity has horny, tooth-like processes. From the mouth extends a long and very muscular cesophagus, which is usually dilated claviform at its lower extremity. When the esophagus is very long, it has one or more constrictions. It is nearly always composed of three longitudinal muscles which are united by longitudinal seams. The triangular cavity circumscribed by these muscles is lined by a very firm epithelium, which is sometimes horny, and in some species so thickly set in the clavate dilatation that it resembles a masticatory apparatus.” The intestine consists of a straight tube, with thin walls and without dilata- Gasterostomum ; and the species above men- tioned I have discovered in the intestinal canal of Perca fluviatilis, and Lucitoperca. 7 See Miram, Owen, and Diesing, loc. cit. The opening at the posterior extremity of many Trema- todes, and by many Helminthologists taken for an anus, belongs to a special secretory organ, which will be mentioned hereafter. 8 In many species allied to Monostomum trizo nocephalum, the two intestinal tubes have simple caeca upon both sides of their entire length. In Octobothrium lanceolatum, the structure is the same; see Mayer, Beitr. p. 21, Taf. III. fig. 3. These lateral caeca are more or less ramified in Oc- tobothrium palmatum, sagittatum, Merlangi, Polystomum appendiculatum, and T'ristomum elongatum (Leuckart, Zool. Bruchstiicke, Hft. 3, p. 26, 54, Taf. I. fig. 4, c. b. Taf. I. fig. 5, d. ; Nordmann, Microgr. Beitr. Hft. 1, p. 79, 81, Taf. VII. fig. 2, Taf. V. fig. 6; and Baer, Nov. Act. Acad. Leop. XIII. pt. 1, p. 665, Taf. XXXII. fig. 2). With Distomum hepaticum, these ramifica- tions are very fully developed ; see Mehlis, Observ. de Distomate, fig. 1, 2, 7,8. In the very remark- able genus Diplozoon, the digestive canal consists of a single tube which traverses the whole body upon the median line, and sends off laterally ramified caeca, while at the point of junction of the two bodies of the animal it dilates into a stom- achal cavity; see Nordmann, loc. cit. Hft. 1, p. 67, Taf. V. fig. 2. The blackish ramifications of Polystomum integerrimum, and which have been regarded by Baer (Nov. Act. Acad. Leop. loc. cit. p. 682, Taf. XXXII. fig. 7,8) and other authors as a digestive canal, belong to the subcu- taneous pigmentary net-work already mentioned. 9 The digestive canal of Trematodes is usually partly filled with blood which they have absorbed, and partly with brown or yellowish chyme ; it is therefore evident how, from the thinness of its walls, it would, when empty, entirely escape the observation. 1 Among the Nematodes, and Gordiacei, there * are, moreover, species which have very rudiment- ary digestive organs. In Sphaerularia bombi, there is neither mouth nor anus, and in the place of the intestinal canal there is a row of long sacs clinging together, and around which the genital or- gans are coiled (Wiegmann’s Arch. 1838, I. p. 305). In Filaria rigida, living in the intestines of Aphodius fimetarius, I have found no digest- ive canal whatever (Miiller’s Arch. 1836, p. 33). In the various species of Mermis, there is a dis- tinct mouth, cesophagus and intestine, but this last ends in acaecum. I have been unable as yet to positively determine a mouth with Gordius aqua- ticus ; the anus is certainly wanting, and it might be questioned if the two tubes which traverse the body should be regarded as an intestine; see Wiegmann’s Arch. 1843, I. p. 305. 2 With Strongylus armatus, hypostomus, den- tatus, and tetracanthus, the entrance of the mouth is provided with a circle of horny teeth, which are moved by special muscles ; see Meh/is, Isis. 1831, p. 78, Taf. Il. fig. 5,6. With Spiroptera stron- gylina, I have seen the entire internal surface of the mouth provided with a spiral, horny swelling. In Cucullanus, there is a very complicated appa- ratus for opening and closing the mouth, composed of solid, horny pieces. 3 With Anguillula fluviatilis, Oryuris vermi- cularis, Ascaris acuminata, brevicaudata, dac- tyluris, oxyura, and vesicularis, the cesophagus has this enlargement. But it is divided into two portions by a prominent constriction with Cucul- lanus elegans, Physaloptera alata, Spiroptera anthuris, europtera, obvelata, and crassicau- da. In Trichocephalus, it is very long, and has behind very many constrictions, which are succes- sive at short intervals ; see Mayer, Beitr. &c. Taf. I. If. With Trichosoma falconum, it is equally long and divided into many sections, which give it an articulated aspect. 4 By many Helminthologists this tube has been called esophagus, and its dilatation stomachus. . 114 THE HELMINTHES. $ 109. tions, and which terminates in a short muscular rectum. The proper intes- tine is of a brown, greenish, or dirty yellow color, which is due to its walls being formed of compact cells filled with colored granules. The loose and cellular walls, having very feeble peristaltic movements, are surrounded externally by a kind of dense peritoneum, and lined internally by a very fine epithelium.” In some species of Ascaris, the intestine is lengthened into a caecum at its junction with the oesophagus.© § 109. There are observed, here and there, only traces of appendant organs of the digestive canal. In many Trematodes, there are upon each side of the neck, two more or less developed cords or canals, of a cellular aspect, and of a pale yellow color by direct light. They pass towards the mouth, open perhaps into its cavity, and have a function, probably, like that of salivary organs.” In many Nematodes, two or four caeca extend from the cephalic extremity along the cesophagus, and as they open distinctly into the oral cavity, it is, therefore, the more probable that they should be regarded as salivary organs.” The same signification should be given to the coecal appendage found in many species of Ascaris, which extends from the constriction of the oesophagus to the beginning of the intestine.” (=) Hepatic organs have been found nowhere but in the Nematodes; but it may be that the granular cells in the thick walls of the intestinal canal, take their place. 5 This epithelium has sometimes special inequali- ties. which, with Ascaris osculata, and spiculige- ra, form a regular zig-zag series, resembling the valves of the intestinal mucous membrane of some vertebrates. With Ascaris aucta, they have the form of long, sharp villosities. 6 This caecal appendage, accompanied usually with a constriction of the posterior end of the cesophagus, was first observed by Mehiis (Isis. 1831, p. 91, Taf. II. fig. 16,17, 18). It is found with many Ascaris, but its length is very variable. In Ascaris heterura, semiteres, and ensicaudata, it is very short, and protrudes scarcely beyond the cesophageal constriction ; while in Ascaris depres- sa, aucta, angulata, and mucronata, it reaches to the middle of the cesophagus, and in Ascaris spi- culigera, osculata, and the species described as Filaria piscium, it extends nearly to the cephalic “extremity.* !} These glandular-like organs are often very distinct in*the cercarian larvae of the Trematodes, and in many adults of Monostomum, and Disto- mum ; see Wiegmann’s arch. 1843, LI. p. 322. 2 Mehlis (Isis, 1831, p. &1, Taf. If. fig. 6) has observed with Strongylus armatus, an annular vessel surrounding the mouth, which communi- * [§ 108, note 6.] See, for the alimentary canal of Ascaris infecta, Leidy (A Flora and Fauna within living animals, Smithsonian Contrib. V. Art. 2, p. 43, Pl. VI. fig. 1-7). He divides it into a strongly muscular gizzard, a cylindroid intestine lined with hexahedral epithelium, and a pyriform rectum. See also his description of that of Streptoso- mum, Thelastomum, &c. (Ibid. p.49). In The- cates with it directly, and also with two cords accompanying the cesophagus. According to him, there is also a similar disposition with Strongylus hypostomus, and tetracanthus. Similar appendages, analogous to salivary or- gans, occur, according to Owen, in the new genus Gnathosoma, as four caeca surrounding the ceso- phagus, and opening into the mouth (Wieg- mann’s Arch. 1838, I. p. 184). With Cheiracan- thus, and Ancyracanthus, there are four similar organs, and Diesing is certainly in error in regarding them as analogous to the ambulacral vesicles of the Echinoderms (Ann. d. Wiener Mus. II. Abth. 2, p. 224, 226, 228, Taf. XVII. fig. 8, 9, Taf. XVIII. fig. 3). Lam disposed to regard as salivary organs, also, the two long caeca which pass from the mouth along the cesophagus of Strongylus striatus. 3 I have discovered a similar oesophageal ap- pendage in a group of Ascaris known as Filaria piscium (Wiegmann’s Arch. 1838, I. p. 309); such are, Ascaris. mucronata, angulata, oscu- lata, spiculigera, aucta, acus, and labiata. It is remarkable that with the exception o the last two, all these have also a caecum upon the intestine. lastomum appendiculatum, there is thi3 pecu- liarity, that the intestine commences by a broad, deeply sinuate, cordiform dilatation, which rapidly narrows to a short, cylindroid portion, and then sends off a long, capacious, gourd-form receptacle, or diverticulum, and afterwards proceeds back- wards to the rectum, and in its course, in the vi- cinity of the generative aperture, performs a single short convolution. — Ep. $ 110. THE HELMINTHES. 115 CHAPTER VI. * CIRCULATORY SYSTEM. § 110. Most of these animals have a vascular system. The circulating liquid is usually wholly colorless, and often contains vesicular or granular cor- puscles, which are difficult to perceive from their delicacy and transparency. The circulation is due to the general contractions of the body or of the walls of the vessels. In the Acanthocephali, the vessels have no proper walls, but are spread out, as has already been said (§ 106), in the subcutaneous parenchyma. There are two larger, lateral canals, which pass from the neck to the caudal extremity, sending off laterally numerous small canals, which anastomose with each other. A similar net-work is found in the proboscis through its whole length.” These two canals connect also with the demnzscz, upon each side of the neck. These last, of which there are always two upon the sides of the proboscis, passing from the neck to the cavity of the body, are usually riband-like, and composed of a finely-granulated parenchyma, which, like the cutaneous one, has a system of vascular canals, In most species of Echinorhynchus, this system consists of a main canal upon the border of the lemniscus, from which are sent off inwardly, nu- merous small branches. These last form the net-work which fills the paren- chyma of the proboscis. In many, the lemnisci are surrounded by muscular fibres, which, con- verging to the posterior extremity of these organs, form two short muscles, which, in their turn, are blended with those passing obliquely to the pro- boscideal sheath. The point of junction is at a short distance from the place where they are detached from the subcutaneous muscular layer. Each lemniscus is constricted into a narrow neck at its base, which passes into the skin at the base of the proboscis. The junction of the cutaneous with the lemniscian vascular system occurs at this point, as is indicated by the contained liquid passing backwards and forwards between the two from 1 This vascular system, taken by many Hel- minthologists for a digestive canal, has been fig- ured by Westrumb (De Helminth Acanthocephalis Tab. If. fig. 10, IIL. fig. 10, 12, 21), and Burow (Echinorhynchi strumosi Anat. 1836, fig. 1, 8). The movements of the nutritive liquid may be distinctly seen by placing these animals alive and undilated as natural under the microscope. One will then be quickly convinced that the circulation is due to the general movements of the body. If Echinorhynchus is placed in much water, the absorption distends not only the body, but the canals of the vascular system are so filled that the subcutanecus parenchyma is swollen, and the skin is raised here and there into vesicles. 2 With Echinorhynchus angustatus, acus, Susiformis, proteus, and polymorphus, the two lemnisci have a riband-like form. In E£chino- rhynchus gigas, they are very long ; and in Echi- norhynchus claviceps, they are longer than the body, and lie coiled in its cavity. In Echino- rhynchus gibbosus, hystrix. and strumosus, they are discoid and very short. 3 Echinorhynchus angustatus, haeruca, poly- morphus, proteus, and gibbosus. As a wide exception, the principal canal occupies the median line of the lemniscii, and sends off laterally small branches, with Echinorhynchus gigas. Here and there its course is broken by oval, voluminous, transparent and apparently vesicular bodies ; see Westrumb loc. cit. Tab. I. fig. 7. Similar bodies in the lemnisci and subcutaneous parenchyma, are found with Echinorhynchus claviceps ; see Mil- ler, Zool. Danica. Tab. LXI. fig. 3. These bodies are, moreoyer, regular neither as to their number nor position, and I have not learned their nature. 4 Echinorhynchus acus, angustatus, fusifor- mis, and proteus. 116 THE HELMINTHES. § 111. the peristaltic actions of the body and the alternate retraction and pro- traction of the proboscis. In the Gordiacei, and Nematodes, no vascular system has as yet been found. Only in a group of species described as Filaria pisciwm, has there been found a riband-like organ concealed in the cavity of the body, and traversed by a net-work of canals, which resemble those of the lemnisci of the Acanthocephali. § 111. In the Cystici, Cestodes, and Trematodes, the vascular system is well developed. Its canals have proper walls, the contraction of which pro- duces the circulation. In the first two orders, it consists of two pairs of longitudinal canals, which pass along the sides of the body and head, and intercommunicate occasionally, by transverse canals. These four vessels open, in the head, into an annular ring which surrounds the proboscideal sheath; there is here, therefore, a completely isolated system.” In the Trematodes, this system consists of a contractile net-work spread over the whole body; and in which are two larger trunks, which pass along the sides of the neck and body. 5 Mehlis (Isis, 1831, p. 82) affirms to have seen on the neck of Echinorhynchus gigas two small orifices by which the lemnisci open outwards. But T have beef unable to see them in this species, or others of this same genus. If they really exist, they will shed light upon the doubtful functions of these organs. From what we know of their struc- ture, it is not improbable that they belong to the nutritive system, and transude a liquid which bathes and nourishes the organs in the cavity of the body.* 6 With the Nematodes, the liquid appears to transude through the walls of the intestine into the cavity of the body, and there bathe, without a vas- cular system, all the organs. The riband-like organ found in the Filaria piscium (see Wiegmann’s Arch. 1838, I. p. 310), and which I have also found in Ascaris osculata, has the same vascular rami- fications as the lemnisci of Echinorhynchus gi- gas, and the vesicle-like bodies are not wanting upon the course of the principal canal. Perhaps they also transude the nutritive liquid, for I have not found any communication between them and the intestinal canal. The two lateral enlargements also, which, as already mentioned (§ 102), are extended between the longitudinal muscles of the skin, have often been regarded as sanguineous vessels ; but I have observed with them neither longitudinal nor lateral canals. 1 These lateral vessels, regarded by some Hel- minthologists as intestinal tubes, give off in their course no lateral branches, except these transverse canals. With the articulated Cestodes, these last are always situated at the posterior extremity of the articulations, thus giving a ladder-like aspect to the entire vascular system. They are also found, however, in Caryophyllaeus mutabilis, which is not articulated. * [§ 110, note 5.] The observations of West- rumb and Burow on the circulatory system of the Acanthocephali, have recently been thoroughly verified by Blanchard, who has illustrated it with excellent figures ; see Ann. d. Sc. Nat. 1849, XII. p. 21, and Régne animal, nouv. ait. Zoophytes, Pl. XXXV. fig. 2. — Ep. Platner (Miiller’s Arch. 1838, p. 572, Taf. XIII. fig. 4, 5) affirms to have seen semilunar valves at the orifices of the transverse canals of Taenia solium. The four lateral cervical vessels which I have observed not only in T'aenia, but also in Bothrio- cephalus, and Cysticercus, may be traced with perfect distinctness in T'aenia cyathiformis, and serrata, to the vascular ring which surrounds the proboscideal sheath. With Caryophyllaeus mu- tabilis, and Taenia ocellata, which are without a proboscis, this vascular ring does not exist any more than with Bothriocephalus ; here also the four lateral vessels widely ramify in the head, and form by anastomoses, a distinct net-work. Both- riocephalus claviceps has a similar organization. It should, moreover, be here observed that from: the contraction of its very thin walls the vascular system will easily elude the observer. 2 The vessels of the Trematodes are remarkable for their prominent flexures ; see Distomum cir- rigerum, tereticolle, duplicatum, and the various species of Diplostomum (Nordmann Microgr. Beitr. Hft. 1, Taf. Il. fig. 8, IV. fig. 5, 6). One should not confound with the sanguineous vessels, as has often been done, the very finely-ramified canals of the excretory organ, which will hereafter be mentioned. Thus I think that the vascular net-work of Distomum hepaticum described by Bojanus (Isis,1820, p. 305, Taf. IV.) belongs to this excretory organ. Zaurer also (de Amphis- tomo conico. p. 10, fig. 22), has not carefully dis- tinguished them ; and Vordmann appears to have fallen into the same error (loc, cit.). With Diplostomum, the vessels open each side into a large reservoir situated at the extremity of the body. Between these two receptacles, the excretory organ passes to the extremity of the body, and Nordmann has taken its orifice as t [§ 110, note 6.] Berthold (Ueber den Bau des Wasserkalbes. &c. loc. cit.) has described a vascular system with the Gordiacei; but Blanchard (Ann. d. Sc. Nat. 1849, XII. p. 7) has failed to confirm his statements after very careful research. — Ep. THE HELMINTHES. 117 § 112. CHAPTER VII. RESPIRATORY SYSTEM. § 112. A respiratory system has not yet been found with certainty in the Helminthes. The pedunculated vesicles of many Nematodes, situated under the skin, and projecting into the cavity of the body, and which have great absorp- tive power, have been compared to trachean pouches and branchiae; but their structure is so little known, that any opinion as to their function ought to be deferred. A remarkable fact is the presence in some Trematodes of extremely active vibratile lobules, situated intermittingly on the inner surface of the walls of the vessels.” It may be questioned if these vessels have a special function, different from that of the others. They somewhat resemble the aquiferous system of the Polyps, Acalephs, and Echinoderms, and like it, belong, perhaps, to the respiratory system. They differ, however, in not having openings which communicate outwardly ; but, probably, they receive by endosmosis, water absorbed by the skin.® But another objection to this view, is, that in this order there has been found nothing like blood-vessels. belonging to the nutritive vessels. The nutritive liquid of the vascular system differs from the coarsely-granulated excretion of the excretory organ, by its homogeneous and colorless aspect. It is remarkable that in Distomum tereticolle this liquid has a reddish color, which, in the finest capillaries has a yellowish cast ; see Wiegmann’s Arch. 1835, I. p. 59. H. Meckel, likewise, thinks that the above-de- scribed vascular system of the Trematodes, is in direct communication with the secreting organ peculiar to these Helminthes ; see Midler’s Arch. 1846, p. 2, Taf. I. fig. 2.* 1 Bojanus (Isis, 1821, p. 187, Taf. IIT. fig. 51- 55) affirms to have observed in Ascaris lumbri- coides these pedunculated vesicles, which are found also in Ascaris depressa, and Strongylus gigas, in connection with the lateral swellings ; but this throws no light upon the nature of these vesicles, for we are yet ignorant of that of these swellings. The stigmata which he affirms (loc. cit. p. 187, Taf. IIL. fig. 56) to have observed upon these lines with Ascaris acus, are, according to my own observations, only subcutaneous cell-like bodies. 21 have quite distinctly seen these vessels with Diplozoon paradorum, Aspidogaster conchi- cola, Distomum echinatum, and an allied species of this last from the intestine of Falco apivorus. *[§ 111, note 2.) Van Beneden (Ann. d. Se. Nat. 1852, XVIII. p. 28) has recently expressed doubts upon the presence of a circulatory system I am yet uncertain if the vibratile organs found in the neck of Distomum globiporum and nodu- losum (Wiegmann’s Arch. 1836, I. p. 218), and in the parenchyma of Distomum duplicatum be- hind the ventral sucker, are of the same nature. Ehrenberg (Wiegmann’s Arch. 1835, II. p. 128) was the first who observed this ciliary move- ment in the vessels of Diplozoon. When the motions of these lobules are free, there is a rapid current of the liquid, as Vordmann has remarked (Microgr. Beitr. Hft. I. p. 69). But if an animal is compressed between two plates of glass, and their motions thus impeded, it will be quickly seen that these last are the cause of the circulation ; in fact, when the lobules cease moving, the colorless, homogeneous, and, without doubt circulatory liquid, is no longer perceived. 3 Burmeister (Handbuch d. Naturgesch. 1837, p. 528) compares, not without reason, this system to the trachean system of insects, the first being aqueous, and the second aerial respiratory organs, thus confounding this vascular system of Helmin- thes with the excretory organ and duct found in most Trematodes. There may be, however, a com- parison between these two systems, if we except the insects with stigmata, and take those which are aquatic and have a completely closed trachean apparatus (see below), admitting no air from with- out. ° with the Cestodes and Trematodes, but see the beautiful plates of Blanchard, Ann. d. Sc. Nat. 1848, X. Pl. XI. — Ep. 118 THE HELMINTHES. § 118. CHAPTER. -Viit. ORGANS OF SECRETION. § 113. No organs of secretion have been found, except in the Trematodes and Nematodes. In most of the Trematodes, there is, upon the median line of the posterior part of the body, a contractile sac, which usually opens out- wards, at the caudal extremity, and seldom at the posterior part of the back.” This sac is single,” bifurcate,® or multiramose. In the last case, its branches are spread usually over the whole body.” Its walls are quite thin, and therefore, it is seen with difficulty when wholly contracted or empty. It contains a colorless liquid filled with numerous granules or vesicles, which, during the contractions, pass up and down, or escape through the external opening. This organ is sometimes so crowded with clear, solid corpuscles, composed apparently of earthy matter, that exam- ined by reflected light, it has a cretaceous aspect.” In many Nematodes, there is on the ventral surface and at a variable distance from the head, a small oblique opening surrounded by a sphincter. In some species, two canals pass from it and run backwards on each side of the intestinal canal; and in others, there are also two other canals which extend forwards in the same way. The use of the colorless and homoge- neous secretion of these organs is yet unknown. 1 This opening, known as the Foramen caudale with Distomum, Holostomum, Monostomum, Aspidogaster, and Diplostomum, has formerly been compared to an anus by Wardo (Heusin- ger’s Zeitsch. fiir organische Phys. 1827, L. p. 68), and by Baer (Ibid. II. p. 197). Mehlis (Observ. de Distomate,p. 16) having shown that it belonged, in Distomum hepaticum, to a particular organ which is ramified like a vessel, has properly re- jected this analogy ; see Isis,1831, p. 179. With the larvae of Trematodes, known as Cercaria, Bucephalus, and Distomum duplicatum the base of the tail is thrust into the excretory opening of this organ, and its contents cannot escape until the animal has lost the tail. 2 Amphistomum. 3 Monostomum faba, Distomum cirrigerum, Gasterostomum fimbriatum, and Bucephalus polymorphus. 4 Distomum chilostomum, clavigerum, lima, maculosum, tereticolle, variegatum, and many species of Monostomum,— where the two closed ends of the sac often extend to the cephalic ex- tremity. With Distomum appendiculatum, the two branches of the excretory organ unite directly behind the oral sucker. With Aspidogaster con- chicola, it divides into two canals near the Fora- men caudale, which extend to the anterior ex- tremity. In Amphistomum, two similar canals wind from the head along each side of the body, to the middle of the posterior back, where they open outwards, after having formed by retinion a pyri- form reservoir. Laurer (De Amphistomo conico. p. 10, fig. 22) has given a figure of this reservoir, in which he has confounded the secretory canals with the nutritive vessels. 5 Beside Distomum hepaticum, Holostomum urnigerum, the Distoma also with a spinous head, have a widely-ramified excretory organ ; see Mehlis, Isis,1831, p. 182. 6 With the spinous-headed Distomum militare, and echinatum, this organ is often so reduced in substance, that here and there are perceived only isolated groups of the ramified canals. 7 The solidity of these corpuscles may have been the reason why Ehrenberg (Symb. Physic. Anim. Evertebr. Ser. I. Phytozoa entozoa) has taken those of Cercaria ephemera for eggs, and the two canals of the excretory organ for ovaries; and why Nordmann (Microgr. Beitr. Hft. 1, p. 54, Taf. I. fig. 7) has regarded their escape from the body with Distomum annuligerum, as an act of ovi- position. The corpuscles of this kind found in the excretory organ of certain Trematodes, as for instance in a larva of Monostomum known as Cercaria ephem- era, remind one from their aspect, of the small calcareous subcutaneous bodies of many Z'aenzae, and it may be asked if they are not an effete mate- rial, which, not being contained in proper organs, is with these Helminthes thus subcutaneously deposited. 5 This organ, to which I first called the attention in the dissertation of Bagge (De evolutione Stron- gyli auricularis et Ascaridis acuminatae, 1841, p. 13), is composed of two canals which run back- wards in Strongylus auricularis, Ascaris brevi- caudata, and acuminata (Bagge, loc. cit. fig. 30, A. B.); and in Ascaris dactyluris, and pauci- para, mihi (from the intestine of T’estudo graeca), of two anterior and posterior canals, the common opening of which is near the middle of the body. $$ 114, 115. THE HELMINTHES. 119 CHAPTER IX. ORGANS OF GENERATION. § 114. Although most of the Helminthes propagate by means of genital organs, yet there are a few species which multiply by fissuration and gemmation, The fissuration is always transverse, and differs from that of the Proto- zoa and Zoophytes in the fact that complete individuals are not produced, there being only a separation of certain organs from the perfect animal, as, for instance that of the segments of the body in the Cestodes. This fissu- ration is complete or incomplete. In the first case, occurring in the Taenia, the segments are detached from the body, and continue to live independ- ently, without, however, ever forming a new individual.” Gemmation has been observed in the sexless Coenurus and Echinococcus. In Coenurus cerebralis, it is incomplete. The buds are formed on the internal surface of the parent-vesicle, and never separate from it, nor become perfect individuals. They have only a head and neck which pro- ject outwardly after the complete development. In Echinococcus, however, the gemmation is complete. The buds appear as in Coenurus, but the young animals are sooner or later detached and fall into the liquid of the parent vesicle. When completely developed, this vesicle bursts, and they are set at liberty. That their development occurs in this way is shown by their hanging by a cord, which, like the tail of Cercarza, is inserted into a fossa at the posterior extremity of the body. Like this last, also, this cord subsequently disappears, and the young animal moves freely about, by the aid of its double circle of hooks and its four suckers. § 115. In those species which reproduce by male and female genital organs, these last are sometimes upon a single animal, and sometimes upon two separate individuals. The eggs and spermatic particles are formed after very differ- ent types. In all, the copulatory organs are extraordinarily developed. The Cestodes and Trematodes are hermaphrodites.” The structure of 1 The imperfect fissuration with Ligula and Triaenophorus is limited almost to a constriction of the lateral borders. With Bothriocephalus punctatus, it is only here and there that a ring is detached, and over most of the body the transverse and opposite sulcations do not extend near to the median line. With Bothriocephalus tetrapterus, the fissuration is more complete ; but even here, there are only some incompletely limited rings among numerous others which are completely so. Of all Helminthes the T’aeniae have the most complete fissuration ; here not only is the separa- tion of the rings indicated by a complete furrow, but the rings are sometimes detached and live thus independently. The separated rings of T'aenia solium, cucumerina, and others, move freely, and are so individualized, that they resemble some Trematodes. 2See Chemnitz, De Hydatibus Echinococci hominis commentatio, 1834 ; Miil/er, in his Arch. 1856, p. CVII. ; and Siedold, in Burdach’s Phys- iol. IL. 1837, p. 183. 1 According to Vordmann (Microgr. Beitr. Hft. 2, p. 141), Diesing (Ann. d. Wiener Mus. I. Abth. 1, p. 9), and Miram (Noy. Act. Acad. XVII. pt. 2, p. 636), the male and female genital organs of the genus Pentastomum, classed hy many modern Helminthologists among the Trema- todes, are situated upon different individuals. But Owen affirms to have observed the opposite (Trans. of the Zool. Soc. of London, 1836, I. p. $25). The only way to settle this point is by analyzing accurately the contents of these organs ; a method pursued by Valentin (Repertorium ITI. 1837, p. 135), who found filamentoid spermatic particles in the organs of an apparently female 120 THE HELMINTHES. § 115. the genital organs of the first is yet imperfectly known; while that of those of the second is well understood. The female apparatus of the Tremato- des consists of a germ-forming organ (ovary), with its excretory duct; then, two others for forming the vitellus, which have also excretory ducts; and then asimple uterus with its vagina. The male apparatus con- sists of testicles with their excretory canals, an internal seminal vesicle, a cirrhus-sac, an external seminal vesicle, and a penis. The ovary consists of a round or pyriform reservoir, situated, usually, upon the median line of the body, from which it is distinguished by its pale color and transparency. It is filled with simple round cells— the ego-germs, The nucleus of these cells is the germinative vesicle, and the nucleolus, the germinative dot. The short and small excretory duct of the ovary opens at the commence- ment of the uterus. The organs which secrete the vitellus are two in num- ber, of variable length, and situated upon each side of the body near the dorsal surface ; they occupy either the cervical, the central, or the posterior portion of the animal, and sometimes extend over them all, They are nearly always composed of ramified caeca filled with white, granular. vitelline corpuscles. By reflected light these caeca appear through the skin as a white, ramified, botryoidal mass, and from each of them, pass off inwardly, numerous excretory ducts, which reunite opposite the ovary into two common canals. These last approach each other transversely, and form a single canal upon the median line, which, after a short course, opens at the bottom of the uterus by an orifice which is common to it and the ovary.” Pentastomum taenioides, organs which are re- garded by Diesing as caeca for secreting the en- velope of the eggs. Since all the parts of the genital organs of Pen- tastomum have not been examined with this same precision, I can give no opinion as to their use.* 2 See Siebold, in Wiegmann’s Arch. 1836, I. p. 217, Taf. VI., and in Miiller’s Arch. 1836, p. 232, Taf. X. fig. 1. 8 The ovary here is always smaller than the testicle, and sometimes as to form very closely resembles it, as in Distomum globiporum, and longicolle, mihi (from the urinary bladder of Cottus gobio) ; consequently it may easily be taken for a third testicle. 4 With Monostomum, it lies wholly at the pos- terior extremity. 5 In Polystomum, Octobothrium and Diplo- zoon, the germs are so large that they may easily be taken for perfect eggs. There is here, moreover, between the cell-wall and the nucleus (the germinative vesicle), quite a thick layer of albuminous substance, somewhat * (§ 115, note 1.) See upon this subject Van Beneden (Ann. d. Sc. Nat. XI. 1849, p. 326), who has described in detail the sexual organs of Lin- guatula Diesingii, and has shown the sexes to be separate. See also my note under § 99.— Ep. + [§ 115, note 7.] To say that certain orgars secrete vitelline cells, is a little obscure, and no doubt Siebold intended to convey the meaning that they secreted the plastic material out of which these cells are formed. I make this perhaps seemingly unnecessary reference to the matter, since it concerns the subject of the development of the ovum. In the Ascaris, where the origin and development of the ovum can be satisfactorily representing a vitellus. But in the other Trema- todes it is so thin as scarcely to be perceived. 6 With the following Trematodes there is a wide deviation from this usual arrangement. In Dis- tomum longicolle the organs producing the vitellus are two simple round caeca located behind the ventral sucker; in Distomum cygnoides, they are two very small deeply-fissured bodies 5 and in Distomum gibbosum, there is one only, which is star-shaped and located at the middle of the body. 7 These organs, until now regarded as ovaries, secrete only vitelline cells. With most Trematodes their nuclei are clear, and have been taken for eggs. In eggs recently formed, one can always distinguish these cells from the germs. In passing the excretory canals they are compressed and elongated, but never,;run into each other. When these canals are crowded, they have the aspect of white cords, which have often been taken for nerves. But when they are empty, they, as well as the vitellus-secreting organs, are almost invis- ible.t studied, you first notice the germs as nucleolated cells, of which the nucleus is the future germina- tive vesicle and the nucleolus the germinative dot. These cells increase in size, and as they move along there appear in the liquid which lies between the nucleus and the cell-wall minute granules which ultimately become cells ; in this way the vitellus is formed, the formation being endogenous and not exogenous. These special organs or tubes therefore are vitellus-forming organs, in vir- tue of their secreting the formative material out _ of which the vitellus is formed within the original. nucleolated germ-cell. — Ep. $115. THE HELMINTHES. 191 The neck of the internal seminal vesicle (Vestcula seminalis interior), discharges its contents at thissame place into the uterus, through a special Vas deferens from one of the testicles. The Uterws commences as a narrow tube, which may be regarded as a Tuba Fallopiz. Its dilated portion, which has powerful peristaltic motions notwithstanding its thin walls, is throughout of nearly an equal diameter. It winds through a large portion of the body and terminates in a narrow, more or less straight, muscular vagina, which always opens externally by the side of the penis. The testicles, of which there are usually two,” are generally of a round or oval form,” and located in the posterior region of the body, nearly always one before the other.“ They are transparent and colorless, and the filiform spermatic particles are extremely small and active.’” The two Vasa deferentia open into the cirrhus-sac, which is perforated at its bottom to communicate with the Veszceula seminalis exterior. From each testicle there passes off, also, a third Vas deferens which opens into the neck of the Vestcula seminalis interior.“ The cirrhus-sac is pyri- formly elongate, or round,” and the Vesicula seminalis exterior is always situated at its base. This last is prolonged, opposite the openings of the vasa deferentia, into usually a very long, tortuous Ductus ejaculatorius, which opens int6é a tubular penis.“ There is one common genital open- ing for the penis and vagina which are usually side by side, and out of which the penis often considerably projects.“ In most Trematodes, these two organs are located at the anterior extremity of the body, and only in Holostomum, and Gasterostomum, are they removed to the other extrem- ity. 8 The length of the uterus varies very much in different genera and species, and its coils are always irregular. With Monostomum mutabile, and verrucosum, the oviduct arising in the poste- rior extremity, passes in front with numerous transverse coils. 9 Ihave found one testicle only, in Amphisto- mum subclavatum, and Aspidogaster conchicola, although I have seen three or four in Distomum appendiculatum, and cygnoides. 10 With Distomum ovatum, the two testicles are side by side behind the ventral sucker ; with Dis- tomum chilostomum, they are on each side of this sucker, and with Distomum crassum, mihi (from the intestine of Hirundo domestica), they are in front of it, on each side of the neck. ll With Distomum longicolle, lanceolatum, oxryurum, echinatum, globiporum, and Amphis- tomum conicum, the testicles have many depres- sions ; see Bojanus, Isis, 1821, Taf. II. fig. 25-27 ; Burmeister and Siebold, in Wiegmann’s Arch. 1835, II. Taf. II. 1836, I. Taf. VI. ; also Laurer, De Amphistomo conico. fig. 21, 24, 25. With Amphistomum subtriquetrum, giganteum, and Distomum hians, the number and depth of these depressions gives the testicle the aspect of a bundle of caeca; see Bojanus, loc. cit. Taf. IL. fig. 14-17, and Diesing Ann. d. Wiener Mus. I. Abth. 2, Taf. XXII. 12 In the testicles of the Trematodes, the devel- opment of the spermatic particles occurs after the usual mode. The Lundles which they form are separated in their passing the vasa deferentia, and they collect into irregular masses in the seminal vesicles. Their extremely active movements cannot be * [§ 115, note 12.] Thaer (Miiller’s Arch. 1850, p. 602, Taf. XXI. fig. 19) has described and fig- 11 perceived unless they are quite isolated. When put in water they become twisted together, and assume a loop-like arrangement, — their motions instantly ceasing. For the development of the spermatic particles of the Trematodes, see Kélliker, Die Bildung du Saamenfaden in Blaschen, loc. cit. p. 44, fig. 31.* 13 These two vasa deferentia are sometimes blended together before reaching their destina- tion; this is soin Distomum variegatum, and longicolle. 14 The internal seminal vesicle is so extraordi- narily large in Distomum variegatum that it exceeds that of the ovary and two testicles. 15 This cirrhus-sac, together with the penis, is very long with Distomum lima, maculosum, variegatum, and ovatum ; but it is especially so with Aspidogaster conchicola, and Monostomum verrucosum. 16 The protruding cirrhus or penis of Distomum holostomum is provided with small bunches ; and that of Monostomum verrucosum with num- berless little warts. 17 When the penis is protruded, it may then be seen how the contents of the vagina are emptied at its base. When the common genital opening is closed, the very flexible penis can be turned into the vagina and there discharge its contents, and in this way the self-impregnation of these animals may occur. 18 The common genital opening is usually sit- uated on the middle of the neck, and with Dis- tomum, it is directly in front of the ventral sucker. With Distomum clavigerum, and ovatum, it is upon the sides of the neck, and with Distomum caudale, and holostomum, exceptionably, it is on ured the spermatic particles of Polystomum ap- pendiculatum as Cercaria-form. — Ep. 122 THE HELMINTHES. § 115. In the terminal, constricted portion of the uterus, eggs, vitelline cells, and spermatic particles are often found mixed together. [tis probably here that the eggs are formed, their fecundation occurring without copulation, and by means of the Vesicula seminalis interior. The succeeding folds of the uterus contain already, nicely-defined, oval eggs containing a germ and many vitelline cells. Their recently-formed envelope is still colorless, and so thin and flexible, that the peristaltic contractions of the uterus give it a variety of forms. But in passing from the uterus they lose this flexibility ; their envelope becomes more solid, — of a yellow and then a brown color ; and the whole, at the same time, undergoes a decrease in size, due prob- ably to a condensation of their substance. The eggs of most of the Trema- todes have an opercular opening at one extremity.“ In the Cestodes, the walls of the genital organs are so very thin, and so intimately blended with the parenchyma of the body, that their structure and relations have not yet been well made out. With the exception of in Caryophyllaeus, these organs are repeated many times one after another, having in the same individual different degrees of development. They are always most complete in the posterior portion of the body, being only rudimentary near the neck, while in the neck itself they do not exist at all. In the articulated Cestodes, each ring contains both male and female sexual organs; and in their two Groups, the arrange- ment of these is the same as in the Trematodes. It is probable that the ovaries and the secreting organs of the vitellus are separate.°? In Lagula, Triaenophorus, and Bothriocephalus, the uterus consists, exactly as in the Trematodes, of a very tortuous tube filled with oval eggs. the posterior extremity of the body. Its position is indicated, even when the penis is not protruded, by a small papilla. With Octobothrium, and Polystomum, there is a round muscular sac concealed directly behind this opening, which contains a circle of delicate horny ribs, the lower extremities of which are bifid and form a support like a bownet. Mayer (Beitr. loc. cit. p. 21, Taf. IIL. fig. 38, 6) has seen ten similar ribs with Octobothrium lanceolatum. Ihave found eight with Polystomum integerri- mum, and forty with Polystomum ocellatum. Their use is wholly unknown to me. 19 The eggs of the Trematodes have apparently only a single envelope. Among the normal eggs in the uterus may often be found others which are mal- formed, also very irregular bodies of a yellowish or brown color, formed almost entirely of the sub- stance of these envelopes. These bodies were most probably secreted by the walls of the uterus (the Tuba Fallopii) at a time when the ovaries and the secreting organs of the vitellus were inactive, so that the substance of the envelopes was hard- ened before recgiving their usual contents. With Amphistomum subclavatum, Octobothrium lan- ceolatum, Polystomum integerrimum, and ocel- latum, anid Diplozoon paradoxrum, the eggs are very large, and in the last-named species their ex- tremities are narrowed and lengthened into a spiral filament, wherefore one of these egzs has been taken for a testicle and penis ; see Nordmann Microgr. Beitr. Hft. 1, p. 73, Taf. V. VI. fig. 1, h.; also Vogt, in Miller’s Arch. 1841, p. 34, Taf. IL. fig. 11. The eggs of Monostomum verrucosum, and some other species of this genus which live in the intestine of Chelonia esculenta, have a very dif- *[§ 115, note 19.] See also for the structure of the genital organs Thaer, Miller’s Arch. 1850, But in ferent form ; they are oval and colorless, and at each extremity have two papillae, which are grad- ually developed into very long, sharp appendages 3 see Dujardin, Hist. Nat. d. “Helminth. Pl. VIII. g. GB. 3+ _ 20 With Caryophyllaeus mutabilis, there is only a single cirrhus-sac upon the ventral surface of the posterior body, and from which a delicate long penis often protrudes. 21 I think I have seen an ovary in each of the segments of Bothriocephalus punctatus, and Tae- nia ocellata. As such, ought, perhaps, to be re- garded those organs which Eschricht (Nov. Act. Acad. L2op. XIX. Suppl. 2, Tab. I. fig. 2, e, e) has considered with Bothriocephalus latus to be ovaries. The organs secreting the vitellus are a mass of irregularly arranged granulations situated upon both the dorsal and the ventral surfaces, and which have very fine excretory ducts. This mass, called by Eschricht (loc. cit. p. 25, Tab. I. fig. 5) the ventral and dorsal granules, cannot, together with its excretory ducts, be made out, except when filled with the vitelline substance. With T'aenia oceliata, the vitelline organs are limited to the sides of each segment, at the anterior border of which two main excretory ducts are easily seen ; these form a single short canal in the middle of the body. In this same place are two transversely- placed oval sacs, and which are probably the two ovaries. 22 The uterine convolutions are generally in the middle of the body, and when filled with mature eggs, appear through the skin as a brown rosette 5 see Eschricht loc, cit. Tab. I. Il. (Bothriocepha- lus latus). p. 602, Taf. XX. fig. 17 (Polystomum appendi- culatum).— Ep. $ 115. THE HELMINTHES. 123 Taenia, it is a reservoir, composed of numerous ramified coeca, and inti- mately blended with the parenchyma of the body.“ The vagina is a nar- row, muscular canal, which usually opens close to the penis by a special orifice (Vulva), or by a common genital opening (Porus genitalis). It is difficult to decide whether the testicles, which always form the middle layer of the body, consist of a collection of inter-opening caeca, or of a single spirally-rolled tube. The cirrhus-sac with the Vas deferens open- ing at its bottom, is always very distinct. As in the Trematodes, it has a Vesicula seminalis, with a Ductus ejaculatorius and a muscular penis.°% The contents of the different canals, the seminal vesicle and the ejacula- tory duct, are always very active, filiform spermatic particles.“ The genital openings are upon the middle of the ventral surface, or on the lateral borders of the body ; but in those species where the sexual openings are separate, they are lateral for the male, and ventral for the female. The eggs of the Cestodes, situated like those of the Trematodes in a spiral, pouch-like uterus, have also a similar structure. brownish-yellow envelope, has also, sometimes, an operculum. Their simple, oval, The eggs of Taenia have a very different structure ; the envelope is colorless, and of a very variable, and sometimes quite remarkable form.“ 23 With most T'aeniae the borders of the cellular uterus are very difficult to distinguish. But its lateral caeca with T'aenia ocellata, and its arbo- rescent divisions with T'wenia soliwm, are very easily seen; see Delle Chiaje, Compendio di Elmintografia umana, Tay. III. fig. 10. 24 The cirrlias-sac is either short and pyriform, or very long. With very many Taenzae, as with Taenia amphitrica, lanceolata, multistriata, scolecina, and setigera, the penis has numerous small spines pointing backwards ; see Dujardin, Hist. d. Helm. Pl. IX.-XI. That of Taenia infundibuliformis is surrounded with very large bristles ; and according to Dujardin (loc. cit. Pl. IX. B. 210) this is also true with T'aenia sinuosa. 25 By very slight pressure, the spermatic parti- cles contained in the Vesicula seminalis of the cirrhus-sac are pressed out through the penis ; this is so with Bothriocephalus punctatus, latus, Taenia cucumerina, pianiceps (from the intes- tine of Hirundo urbica), inflata , pectinata, ser- pentulus, and villosus. As with the Trematodes, the spermatic particles here cease to move when put in water, and are twisted into loops.* 26 With Ligula, Bothriocephalus nodosus, latus, claviceps, ditremus, punctatus, and te- trapterus, the two genital openings are situated on each side of the ventral surface, while the penis protrudes from a special opening directly in front of the vulva; see Mehdis in Isis, 1831, Taf. 1. fig. 1, 2, and Eschricht, loc. cit. Tab. I. fig. 5. With Bothriocephalus punctatus, there are two pairs of these openings upon each segment, one under the other, but in Bothriocephalus te- trapterus, these are side by side. With T'riaeno- phorus, nodulosus,and Taenia ocellata, the vulva is upon the ventral surface, and the penis upon the lateral border. With Bothriocephalus fra- * * [§ 115, note 25.] I have observed the de- velopment of the spermatic particles with T'aenia. They are developed in special cells, and before they have escaped,are therein coiled up resembling those of the coleopterous insects. They are simply filiform. — Ep. t [§ 115, note 26.) The Cestodes have been the objects of much careful study during the last few gilis, proboscideus, rugosus, and with most T'ae- niae, the cirrhus-sac and the vagina open by a common genital orifice upon the lateral border, and usually through a papilla. With T'aenia cucumerina, and bifaria, mihi (from the intestine ot Anas leucophthalmus), I have found an orifice of this kind upon the two lateral borders of each pie and behind which were the genital or- gans. 27 Although I have not seen either the germina- tive vesicle or dot in the eggs of the Cestodes, probably from their delicacy, yet I do not fora moment doubt their presence there, since K élliker (Miiller’s Arch. 1843, p. 92, Taf. VII. fig. 44) has seen them in the eggs of a Bothriocephalus. Many species of this genus produce oval eggs which have a simple brown envelope. Of an oval form, but colorless, are those of Caryophyllaeus, Ligula, Triaenophorus, Taenia literata, and scolecina. Those of Taenia amphitricha, bifa- ria, macrorhyncha, serpentulus, and serrata, are round, and have two colorless envelopes ; this is true also of the oval eggs of T'aenia angulata, villosa, &c. There are three of these envelopes with the round or oval eggs of Bothriocephalus infundibul- iformis, proboscideus, Taenia porosa, lanceo-~ lata, ocellata, setigera, and solium. With T'ae- nia infundibuliformis, and planiceps, each ex- tremity of the envelope is lengthened into a long and delicate appendage. Two similar but fibril- lated appendages exist upon those of T'aenia variabilis. With Taenia cyathiformis, the ex- ternal pyriform envelope of the eggs has, at its attenuated extremity, two round, bladder-like ap- pendages. Dujardin (Hist. d. Helm. Pl. IX.- XII.) and I (Burdach’s Physiol. 1837, II. p. 201) have seen many other forms with the eggs of Taenia. The round and doubly-enveloped eggs years, by Blanchard (Ann. d. Sc. Nat. X. 1848, p- 321) and Van Beneden (Mem. Acad. Belgique, 1850, XXV.) and the sexual parts pretty clearly made out. They both agree that, internally, the male and female organs are wholly distinct, and therefore that impregnation of the ova must be by self-copulation. — Ep. THE HELMINTHES. $ 116. § 116. In the Acanthocephali, the genital organs occupy a large portion of the cavity of the body. They arise in the posterior portion, and are supported by a Ligamentum suspensorium, which extends from this last to the base of the proboscideal sheath. In the females, there are neither proper ovaries, nor an uterus; but in their place there are numerous oval, or round, flattened bodies of consider- able size, which float freely in the liquid of the cavity of the body; they have nicely-defined borders, and are composed of a vesicular, granular substance, and, as eggs are formed within them, they may be regarded as so many loose ovaries. When the eggs have reached a certain size, they fall from the ovaries into the cavity of the body. At this time they are ovo-elongate, have only a single envelope, and contain both a vesicular and a finely-granular substance, but no trace of a germinative vesicle. They continue to in- crease in size, and two new envelopes are formed about them.% The muscular canal which passes off from the simple vulva which is situated at the posterior part of the body, may be regarded as a uterus. At the point where it is attached to the Lzgamentum suspensorium, it becomes a campanulate or infundibuliform organ, whose borders float freely in the cavity of the body, and thus the whole is comparable to a Tuba Fal- lop. The bottom of this bell-shaped organ communicates with the superior extremity of the uterus by a narrow, valvular opening, which presents a lateral, semilunar fissure. This whole organ is endowed with very active peristaltic motions, by which the loose contents of the cavity of the body are absorbed; and while the larger ovaries are thrown out, the little immature eggs are returned into the cavity of the body by the lateral fissure, — the more mature ones only, reaching the uterus. This uterus, which is of variable length, opens outwardly through a very short and narrow vagina. The males of Echinorhynchus have usually two oval or elongated testi- cles, one before the other, and attached to the Ligamentum suspensoreum. of Taenia cucumerina (Creplin, Obsery. de Entozois fig. 12, 18) and crateriformis, have the remarkable arrangement of being grouped in tens to twenties, and each group is surrounded by a gelatinous envelope.* 1 The ovaries of Echinorynchus were formerly taken both for mature eggs, and for cotyledons ; and to this is due the very inaccurate figures of them by Westrumb and Cloquet (loc. cit.). Du- jardin, however (Hist. d. Helm. Pl. VII. fig. D. 6), perceived their true nature. A state of development which I have observed with many females of Echinorhynchus gibbosus, would appear to throw some light upon the ques- tion as to the part of the body where the ovaries are first formed. Here the Ligamentum suspen- sorium had, over most of its extent, large granu- lar globules, while the cavity of the body contained neither ovaries nor eggs. I think, therefore, that this ligament is the elementary material from which the ovaries are developed under the form of glob- ules, which, being subsequently detached, continue their development in the liquid of the cavity of the body. * [§ 115, note 27.] See Van Beneden (loc. cit. p- 67), who has observed the eggs of the Cestodes 2 The long eggs of many Echinorhynchi are formed by the same process. They are all colorless, and may be distinguished by the peculiar aspect of their middle envelope which at both extremities is constricted like a neck. But those of Echino- rhynchus gigas form an exception ; for they are shorter and oval, their middle envelope is yellowish, and, like the two others, has externally numberless small obtuse spines. With Echinorhynchus stru- mosus, hystrix, angustatus, and proteus, the external envelope of the eggs presents the peculiar phenomenon that when pressed between two plates of glass, it separates into very fine fibrillae. 3 The nature of this campanulate Tuba Fallopii has been wholly mistaken by Bojanus, Westrumb and Cloquet. Burow (Kchinorhynchi strumosi Anat. p. 22, fig. 1. g, fig. 6) was the first to describe it, without however conveying the correct idea. See my description (Burdach’s Physiol. loc. cit. p. 197), which has been confirmed since by Dujardin (Hist. d. Helm. p. 495, Pl. VII. fig. . . composed like those other animals,— with a germin- ative vesicle, &c.— Eb. $ 117. . 125 They send off two varicose Vasa deferentia to the posterior portion of the body, where, after uniting very probably with the neck of an odd elongated vesicle (Vestcula seminalis ?), they are prolonged into a copula- tory organ.” There are six pyriform bodies, which secrete a finely-granu- lar substance, and are attached behind the testicles to the Vasa deferentia. Their six excretory ducts successively unite, ending finally in two which open into the copulatory organ. The penis is usually folded inward, but when projecting outwardly, it is a muscular, cup-shaped appendage, whose fossa receives the posterior portion of the body of the female during THE HELMINTHES. copulation. The spermatic particles are developed after the usual mode; they are filiform and very active, and quickly die in water, interlooping and twisting together.© The very adhesive, viscous, yellowish-brown wax-like substance, often found about the vulva, is apparently the secretion of the pyriform bodies during copulation. ® § 117. With the Nematodes, the genital organs consist of a long, simple or partly double caecal tube, which winds around the straight intestine. In the female it has the following parts: Ovarium, Tuba Fallopii, Uterus, and Vagina; and in the male, Testes, Vas deferens, Vesicula seminalis, and Ductus ejaculatorius. With Trichosoma, Trichocephalus, and Sphaerularia, the genital tube is simple in the females, and usually so in the males. But in Filaria, Asca- ris, Strongylus, Spiroptera, Oxyuris, and Anguillula, the ovary, Fallopi- an tube, and uterus, are double.” In the females, the ovary is the poste- rior portion of this genital tube, and in its terminal portion are small round 4 With Echinorhynchus strumosus, these two round testicles are side by side. Having always found the odd, long vesicle empty, I cannot decide whether or not it serves the function of a seminal vesicle. 5 These six pyriform bodies were formerly taken for seminal vesicles ; see Westrumb, de Helminth. Acanthocephalis, p. 55, Tab. III. fig. 243; and Nitzsch, in Ersch and Gruber’s Encyclop. VII. 1821, plate for the Acanthocephala, fig. 2, 3, i. With Ecninorhynchus claviceps, I have found only one of tliese bodies. 6 The copulatory organ, which protruded has mostly an oblique direction, has been very exactly figured by Dujardin (Hist. d. Helm. p. 493, Pl. VI. fig. D, 1, D, 2). 7 For the spermatic particles of the Acanthoce- phali, see my observations in Muller’s Arch. 1836, p. 252. 8 This waxy substance incrusts sometimes the whole caudal extremity of females ; this is so with Echinorhynchus gigas,and globocaudatus ; see Cloquet (Anat. &c. &c. p. 100, Pl. VIII. fig. 4,5) and Nitzsch (Wiegmann’s Arch. 1837, I. p. 64.* 1 For the simple genital tube with its various parts of the female of T'richocephalus dispar, see Mayer, Beitr. &c. Taf. Ul. With Filaria rigida, * [§ 116, note 8.] For some further details on the genitalia of the Acanthocephali, see Blanchard (Ann. d. Sc. Nat. 1849, XII. p. 23), and Régne 11* and Ascaris paucipara, I have found the female organs likewise simple. When these organs are double, either one uterus with its ovary and ovi- duct passes in front from the simple vagina, while the other passes behind, as is the case with Ascaris brevicaudata, nigrovenosa, Oxyuris vermicu- laris, Spiroptera anthuris, Strongylus auricu- laris, and striatus; or both pass side by side behind, as in Ascaris aucta, mystax, lumbri- coides (Cloquet, Anat. &c. Pl. I. fig. 2) and aus- culata. With Cucullanus elegans, and micro- cephalus (from the intestine of Emys lutaria), the uterus alone is double; one horn terminating posteriorly in a caecum without an ovary or Fallo- pian tube, while the other, which has these parts, passes in front. There are, moreover, species of Ascaris into whose vagina open three or four geni- tal tubes. Thus with Ascaris microcephala, I have seen the uterus divide upon reaching the vagina into three tubes, each having an ovary and oviduct. According to Nathusius (Wiegmann’s Arch. 1837, I. p. 57), the uterus of Filaria labiata, which is at first simple, divides at its posterior ex- tremity into five tubes. The double uterus of Strongylus inflerus has, posteriorly, numerous constrictions, giving it a moniliform aspect. animal nouy. édit. Zoophytes, Pl. XX XV. fig. 3v, 3c, 3d, Se, 3f), — Eb. 126 THE HELMINTHES. $4117. cells; in the anterior portion, these cells are more numerous and begin to be surrounded by a granular vitelline substance, in which the primitive nucleated cells are still seen; these cells therefore, ought perhaps to be regarded as germinative vesicles. In front, these eggs, which are of a dis- coidal form, are arranged in a row, or are grouped closely around a rachis which traverses the axis of the ovary. In the Fallopian tube, which may be known by its less diameter, the eggs become more mature, and, having been surrounded by a double colorless envelope, pass into the base of the uterus.” This last is the largest portion of the genital tube, and is dis- tinguished by its well-marked power of peristaltic action. The vagina, which is distinguished from the uterus by its narrowness and its muscular walls, opens at very different points of the body. Generally, as for instance in Ascaris, Spiroptera, Strongylus, Oxyuris, Cucullanus, and Tri- chocephalus, the Vulva, consisting of a transverse fissure, and often sur- rounded by a very remarkable fleshy swelling, is situated either a little in front of, or near the middle of the body ; but sometimes it opens just in front of the anus. The sperm is usually so accumulated in the bottom of the uterus, that this is probably the locality of fecundation.© In the males, the posterior portion of this tube is the testicle; another portion of it, which is short and constricted, is the Vas deferens, which passes into a dilated portion,— the Veszcula seminalis. Usually this last is separated by a constriction from the Ductus ejaculatorius, which opens into another muscular tube (sheath of the penis). At the anterior portion of this last, is a horny, copulatory apparatus. The simple or double penis is of variable length, and is protruded by the muscular contractions of its sheath through the external opening, which is always situated at the poste- 2 The formation of eggs in various Nematodes has been described by Siebold (Burdach’s Phys- iol. loc. cit. p. 208), by Bagge (Dissert. de. Stron- gylo, &c., fig. 1-5), and Kélliker (Miller’s Arch. 1848, p. 69, Taf. VI. fig. 20). I have found a rachis in the ovaries of Ascaris aucta, lumbri- coides, mystax, osculata, Cucullanus elegans, and Strongylus inflexus. The eggs of these, while yet immature and flattened, have a point on one of their extremities by which they are attached to the rachis. With those of Ascaris lumbricoides, this point is very long during a certain period of develop- ment, and the opposite end has many deep sulca- tions, giving it a remarkable appearance ; see Henle, in Miiller’s Arch. 1835, p. 602, Taf. XIV. fig. 11. In the mature eggs, which are nearly always oval, it israre that the double colorless envelope can be clearly perceived. With T'richosoma, and Tri- chocephalus, there is a short diverticulum at each extremity of the egg. But in Ascaris dentata, there is at this same place a long fibrillated filament; see Mayer, Beitr. Taf. II. fig. 8, and Kélliker, in Midler’s Aych. 1843, Taf. VI. fig. 16-19.* 38 With Ascaris dactyluris, Cucullanus ele- gans, Strongylus nodularis, and striatus, the * [§ 117, note 2.] Primitively, the ova of Asca- ris consist of nucleolated cells, which are polyhe- dral from mutual pressure. These increase in size gradually, in their passage down towards the ovi- duct, and the granules of the liquid lying between the nucleus or germinative vesicle and the cell-wall borders of the vulva appear quite swollen. With Trichosoma, this swelling is so attached to the vulva as to resemble a prolapsus of the vagina (Dujardin, Hist. d. Helm. PI. 1.). ’ With Filaria attenuata, inflexo-caudata, mihi (from the pulmonary cysts of Delphinus pho- caena), and papillosa (see Leblond, Quelques matériaux pour servir a Vhistoire des Filaires et des Strongles, 1836, Pl. II. fig. 1), the vulva is at the side of the mouth. With Strongylus paradoxus, it is swollen to the form of a bladder, and is situated near the caudal extremity ; while that of Ascaris paucipara is directly upon the anus. 4 See Bagge, loc. cit. p. 12; and Kélliker, in Miiller’s Arch. 1843, p. 72. 5 For the male genital tube, see Mayer, Beitr. Taf. I., and Cloquet, Anat. &c. Pl. I. fig. 5, Pl. II. fig. 8. As yet I have observed only a few exceptions to this typical form with male Nemia- todes. With Filaria attenuata, the posterior portion of the testicle is bifurcate, and with Ascaris vesi- cularis, there are two moderately large caecal pro- longations which arise from the Vesicula semi- nalis at the place where it empties into the Vas deferens. become developed into cells, and in this way the mature ova are formed. Probably no better op- portunity is afforded to perceive that morphologi- cally the ovum is at first only a nucleolated or nucleated cell; see Lezdy, loc. cit. p. 48, Pl. VII. fig. 14, c. — Ep. - § 117. THE HELMINTHES. 127 rior portion of the body. It has a great variety of forms, and from its sheath arise two antagonistic muscles, which are inserted at its base.” The spermatic particles, which are always motionless, have usually a cell-form, or, at least, are never filiform corpuscles. For aiding the union of the sexes during copulation, the males have lobular appendages, papillae. and suckers, situated about the genital opening. Without doubt, the spiral pos- terior extremity also of the animal, is often used for the same purpose. Moreover, in many instances, there is secreted a wax-like substance in- tended to fasten the two sexes together. 6 According to Leblond (loc. cit. p. 20, Pl. III. fig. 1), both the male and female genital openings with #ilaria papillosa are quite near the oral ori- fice. Ihave been unable to confirm this observa- tion, at least with Fi/aria attenuata, inflexo-cau- data, and another species found in the thoracic cavity of Sturnus vulgaris. 7 With Trichocephaius, and Trichosoma, the penis is simple and very long, and, beside the mus- cular sheath, has another which is membranous, and sometimes covered with small spines pointing backwards. This sheath, being folded outwards when the penis is protruded, is comparable to a Praeputium ; see Mayer, Beitr. loc. cit. Taf. I., and Dujardin, Hist. d. Helm. Pl. I-III. With nearly all the other Nematodes the penis is double. ft is very long with Ascaris acuminata, brevi-~ caudata, depressa, spiculigera, and Strongylus paradozrus ; but is very short with Ascaris ensi- caudata, semiteres, Cucullanus elegans, Fila- ria attenuata, inflexo-caudata, Spiroptera an- thuris, and Strongylus inflerus. With Spirop- tera, the two penises are of unequal length, and with Ascaris paucipara, brevicaudata,and Stron- gylus, there is an additional horny piece like a third penis. With most Nematodes, the penises are sulcated, and those of Strongylus have a singular form due to the presence of numerous appendages. ‘The two delicate, retractor muscles of this organ, arise from the internal surface of the cavity of the body, and when the penis is double there are two pairs. With Ascaris osculata, vesicularis, and spicu- ligera, I have found these four muscles very long. See upon the penis of the Nematodes, Mayer, Beitr. Taf. I., and Dujardin, Hist. d. Helm. Pl. I-VI. 8 For the spermatic particles of the Nematodes, see Bagge, Dissert. de Strongylo, &c., p. 12, fig. 27, 28. The development of these cell-like spermatic particles may be easily observed with Ascaris paucipara, where the parent-cells are very large. In the posterior end of the testicle the *(§ 117, note 8.] The statement here made that Reichert has observed the development of the spermatic particles of an Ascaris by fours in each cell, deserves attention from its histological relation. According to my own observations,the histological formative conditions of the development of the spermatic particle are exactly analogous to those of the development of the embryo. The nucleus of the sperm-cell divides or segments like the vitel- lus of the ovum, and this process continues until the sperm-cell which has now attained a large size, is filled with numerous small nucleated cells (daughter-cells) ; and the nucleus of these last is changed into the spermatic particle. I think, therefore, that, invariably, the spermatic particle is only a metamorphosed nucleus of a nuclei with their nucleoli are first formed ; after- wards these nuclei are surrounded by a finely- granular substance around which the cell-mem- brane is formed. In this state the testicle exactly resembles an ovary filled with germinative vesicles and eggs. Still later, the parent-cell membrane increases more and more, and the granular substance is found only upon the internal surface of the cell. During these changes, the nucleus which resembles a ger- minative vesicle, is transformed into a long, solid, and neatly-circumscribed corpuscle. With Stron- gulus auricularis, the spermatozoal [laughter ?} cells are pyriform ; and with Oxyuris ambigua their form is similar (Kélliker, loc. cit. p. 73, Taf. VII. fig. 26). It is very probable that Mayer’s assertion (Neue Untersuch. aus dem Gebiete der Anat. u. Physiol. 1842, p. 9) that he had seen thread-like spermatic particles with Oxyurtis vermicularis, has led Kaélliker to regard these pyriform cells as so many bundles of filamentoid spermatic particles. But never have I seen filaments of this kind in the Ne- matodes. The pyriform spermatic particles of Strongylus auricularis, which have a short peduncle, as well as the round, cell-like, and nucleated ones of As- caris acuminata, have been figured by Reichert (Beitr. zur Entwickel. der Saamenkérp. bei den Nematoden). This same naturalist has shown that these spermatic particles arise by endogenous gen- eration, by fours in each cell; see Muller’s Arch. 1847, p. 88, Taf. VI.* 9 The large caudal valve of the male Strongylus, and the spiral tail of the male Spiroptera, may be here instanced. With very many male Ascaris, there are two rows of papillae upon the sides of the genital opening, and with Ascaris vesicularis, and inflexa, I have found a copulatory sucker directly in front of this opening. The male of Hedruris androphora winds himself about the female during copulation, and the caudal valve of the male Strongylus trachealis glues itself so daughter-cell (see my Memoir, The Origin, De- velopment, and Nature of the Spermatic Particles in the four classes of Vertebrata, in the Mem. Amer. Acad. of Arts and Sc. V. 1853). The view of Reichert, therefore, that four spermatic parti- cles are here formed in one cell, does not appear to me admissible, although I have no observations upon the instance in question. It appears to me explicable in this way: the nucleus of the parent sperm-cell underwent here only a second segment- ation, thereby only four daughter-cells being pro- duced. The nucleus of each of these became a spermatic particle, and these four particles passed into the cavity of the parent-cell. Reichert there- fore, probably saw four spermatic particles in o parent and not in a daughter cell. — Ep. 128 THE HELMINTHES. $ 118. The few observations hitherto made upon the genital organs of the Gor- diacei have shown that they are wholly tubular as in the Nematodes. But their intimate structure, and the development of their spermatic particles are so strikingly different, that this point alone would justify their separ- ation from the Nematodes.“ , § 118. With the exception of the Nematodes, and Gordiacei, the development of all Helminthes, which reproduce by means of genital organs and eggs, is metamorphotic. A complete series, from beginning to end of these meta- morphoses has yet never been observed with any species. From the separate parts of it here and there which have been observed, there appears the remarkable fact, that the embryos after escaping the egg, are not always changed at the end of the metamorphosis, into individuals like the parent, but appear as larva-like animals, capable in their turn of producing other larvae. These last larvae alone, change into individuals, which are like the parent. This particular kind of transformation and development which is quite common among the Trematodes, has received the name of Alternate Gene- ration.” Whether it occurs among the Cestodes and Acanthocephali, cannot now be stated positively, for as yet we are unacquainted with the first period of their metamorphosis, — the embryo as it escapes from the egg. In many Cestodes and Trematodes, the embryos are developed before the eggs are cast, and in some of the last order, they make their escape while the eggs are in the uterus. The development of the Cestodes occurs as follows: After the disap- pearance of the germinative vesicle, large, transparent embryonic cells appear in the midst of the vitellus, which undergoes fissuration. These multiply by division, increasing at the expense of the vitellus, which in the tightiy to the vulva of the female in this act, that they cannot disengage themselves (Stebold and Nathusius, in Wiegmann’s Arch. 1836, I. p. 105, Taf. IIL. 1837, I. p. 60, 66). With many other species of Strongylus, and Ascaris, it is not rare to find a brownish gum about the vulva, and in which there is, sometimes, the very distinct impress of the male caudal valve (Mehits, Isis,1831, p. 87).* 10 In the genus Mermis formed by Dujardin, the tubular uterus, the muscular vagina, and the vulva situated far from the caudal extremity, — all remind one much of the Nematodes. The eggs of Mermis nigrescens, like those of Ascaris den- tata, have long fibrillated appendages (Dujardin Ann. d. Sc. Nat. 1842, XVIII. p. 133, Pl. Vi., and Siebvold, in Wiegmann’s Arch. 1845, IT. p. 309) 5 and at the caudal extremity of the males of Mermis albicans, mihi (Entom. Zeit. 1845, p. 79), there are, as in most Nematodes, two horny penises. But with Gordius, the structure of the genital organs is very different (see Siebold, and Dujar- din, loc. cit.). In both sexes the cavity of the body is completely filled with a double genital tube, straight, and simple posteriorly, the sides of which ae formed of large cells. The genital _* [§ 117, note 9.] For many details of the re- productive organs of Ascaris infecta,with beauti- ful illustrative figures, see Lezdy, A Flora and Fauna, Xc., loc. cit. 4 B. Pl. VII. 14, 16, b. 19.— Ep. + [| § 118, note 2.] The view here suggested of opening is always at the posterior extremity of the body. The testicular tubes of Gordius aquaticus contain anteriorly, cell-like bodies ; but posteriorly there are others, staff-like, and which, being found among the eggs in the uterine tube, [ have regarded as perfect spermatic particles. The genital open- ing of the male Gordius is between the two more or less prominent lobes of the caudal extremity, and is without copulatory organs. The simple, round, colorless eggs, are bound together at the posterior part of the uterus by an albuminous sub- stance, and are deposited in a very long row. It is this row of eggs which Léon Dufour has described as Filaria filariae (Ann. d. Sc. Nat. XIV. 1828, p. 222, Pl. XII. fig. 4). 1 See Steenstrup, Ueber den Generationswech- sel, &c., 1842. 2 In various marine fish thee is a trematode larva of a Tetrarhynchus (Miescher, Bericut ueber die Verhandl. d. Naturforsch. Gesellsch. in, Basel. 1840, p. 29, and in Wiegmann’s Arch. 1841, IL. p. 802), which would lead one to con- clude that alternate generation exists also with the Cestodes.t the alternating generation of the Cestodes, has recently been confirmed most thoroughly by Sie- bold, who has treated the subject in a most com- prehensive manner, in a Memoir in Stebold and Kiolliker’s Zeitsch. IL, 1850, p. 198. — Ep. §$ 118. THE HELMINTHES. 129 end they completely replace. When this has taken place, there is a mass of extremely small cells, which, being covered with a delicate epithelium, form a round or oval embryo, upon one extremity of which there are grad- ually formed six small horny hooks. The embryos of the Acanthocephali are perhaps developed in the same manner, but they have only four hooks.“ The Trematodes are developed exactly like the Cestodes, excepting that their oval embryos have usually ciliated epithelium, and there is an oral sucker in place of the hooks, Beside this first period of development, or other more advanced or larval states, during which many Helminthes have been described and figured as separate species in the science.© Among these may be especially noticed two forms of the Trematodes — the cylindrical and the cercarian larvae. The first (the germinative tubes of Baer), form one of the phases of the alternate generation, and have a more or less complete organization. In the cavity of their body, germinative corpuscles are formed; these consist of a vesicular, granular substance, and resemble eggs neither by their structure nor mode of development. These corpuscles produce larvae of a cylindrical or cercarian form, which, deprived of their tail, are changed into perfect animals which have genital organs; and thus the series of metamorphoses is terminated. 83 For the embryonic development of Bothrioce- phalus, and Taenia, see Siebold (Burdach’s Phys. loc. cit. p. 200), Dujardin (Ann. d. Sc. Nat. X. 1838, p. 29, Pl. I. fig. 10, also XX. 1843, p. 341, Pl. XV., and his Hist. d. Helm. Pl. [X.- XII.), and Kélliker (Miiller’s Arch. 1843, p. 91, Taf. VII. fig. 44-56). The small hooks which the cestoid embryos so actively protrude and retract, somewhat resemble those which are circularly arranged with the adult Taenia.* 4 As yet, with Echinorhynchus gigas alone have I succeeded in liberating the embryos from the egg by compression. The four hooks of these embryos resemble, by their form and position, those of the Cestoid embryos. It does not appear, how- ever, that the embryos of all Echinorhynchus have them ; at least Dujardin has not found them with those of Echinorhynchus transversus, and globocaudatus (Hist. d. Helm. Pl. VII.). 5 For the embryonic development of Monosto- mum, and Distomum, see Siebold (Burdach’s Phys. loc. cit. p. 206), and Kélliker (Miiller’s Arch. loc. cit. p. 99). The embryos which swim about like Infusoria by means of ciliated epithelium, and which escape the egg while yet in the uterus, have been observed of Distomum hians, by Meh- lis (Isis 1851, p. 190) 5 of Distomum nodulosum and globiporum, by Nordmann and Creplin (Microgr. Beitr. Hft. 2, p. 189, and in Ersch and Gruber’s Eneyclop. XXIX. 1857, p. 324); of Distomum cygnoides, longicolle, Amphisto- mum subclavatum, and Monostomum mutabile, by myself (Wiegmann’s Arch. 1835, I. p. 66, Taf. I.). See also Dujardin, in the Ann. d. Sc. Nat. VIII. 1837, p. 303, Pl. IX. fig. 3. I haveseen the embryos of* Distomum tereticolle, and Aspido- gaster conchicola, without the ciliated epithelium. *{§118, note 3.] The history of all our best embryological studies shows that the segmentation of the vitellus is the invariable preface to the be- ginning of development with all true ova. In the case of the Cestodes, if, as above mentioned, there is no such process, it is highly probable that such Those of Distomum longicolle, cygnoides, Mon- ostomum mutabile, and Aspidogaster conchi- cola, have an oral sucker. In this last species, there is another sucker also, at the posterior ex- tremity of the body (Dujardin, Hist. d. Helm. p. 325). 6In this category are the genera Cercaria, Histrionella, Bucephalus and others, which as yet have been founded only upon different species of Trematode larvae. The Helminth described by Leblond (Ann. d. Sc. Nat. VI. 1836, p. 289, Pl. XVI. fig. 3) as Amphistomum ropaloides, is only a larva of a T'etrarhynchus. The species forming the genus Scolex are certainly only imperfect Bothriocephalus ; and the Gryporhynchus pu- sillus of Nordmann (Micr. Beitr. Hft. I. p. 101, Taf. VIII. fig. 6, 7), is probably only a young Taenia. There may also be a doubt here, if the Cystici can be considered as real species. It is very probable that they are imperfect Ces- todes whose genital organs are to be afterwards developed, as with Cysticercus fasciolatus, while the Rodents in which it lives are devoured by car- nivorous animals. T'aenia crassicollis is, per- haps, to Cysticercus fasciolaris, what Bothrioce- phalus nodosus is to Bothriocephalus solidus ; see Creplin, Nov. Observ. &c. p. 90. 7 The cylindric larvae of the Trematodes have been termed by Steenstrup (loc. cit. p. 50) nurses (Ammen). They are yet known only as living parasitically upon Mollusks, as for instance, upon Paludina, Lymnaeus, Planorbis, Ancylus, Suc- cinea, Anodonta, and Unio; also upon Helix pomatia, and Tellina baltica, according to Boja- nus, Baer, Carus, Steenstrup, and myself. The cylindric larvae of Bucephalus polymorphus, are very long tubes, varicose here and there, some- times ramified, and which do not exhibit any development is not from true eggs but rather from buds, a view which is the more worthy of attention from the recent developments made by Siebold with Gyrodactylus ; see below, my note under § 118, note 7. — Eb. » embryonic state, there are’ 1380 THE HELMINTHES. $ 119. § 119. With the Nematodes, of which very many are viviparous, the embryos are developed within the egg in two movements (Baer, in the Nov. Act. Acad. Leop. XIII. pt. 2, p. 570, Tab. XXX.). Those of Dis- tomum dupiicatum have simple, oval, and rigid germinative utricles (Baer, Ibid. p. 558, Tab. XXIX.). Those of Cercaria ephemera, are also very simple, but of a cylindrical form (Szeboid, in Burdach’s Phys. loc. cit. p. 187, and Steenstrup, loc. cit. p. 78, Taf. III. fig. 1-6). Those of Cer- caria furcata are simple and cylindrical, but very long and endowed with quite active peristaltic motions (Baer, loc. cit. p. 626, Tab. XXXL. fig. 6). The curious animal, Leucochloridium paradox- um, consisting of only a cylindrical sac with a tail, is only a trematode larva (Carws, in the Nov. Act. Acad. Leop. XVII. pt. 1, p. 85, Tab. VIL.). With the slow-moving, cylindrical, orange-colored nurses of Cercaria ephemera, there may be easily seen a mouth, a pharynx, and a simple coecal intestine (Siebold, in Burdach’s Phys. loc. cit. p. 187). Those of Cercaria echinata, are similar, but they have also two short oblique prolongations in front of the obtuse caudal extremity (Baer, loc. cit. p. 629, Tab. 31, fig. 7, and Steenstrup, loc. cit., p. 51, Taf. Il. fig. 2-4). The germinative bodies from which Cercaria is developed, have nothing comparable to a chorion or germinative vesicle. Their larvae have always a tail, which is simple (Cercaria armata, ephemera, Distomum dupli- catum), or bifurcated (Cercaria furcata), or double (Bucephalus polymorphus). The move- ments of this tail are very slow with Distomum duplicatum, but extremely lively and vortical with Cercaria. With Bucephalus, the two fili- form tails lengthen and shorten considerably, at the same time jerking all about. When the larvae are developed, they leave the corpuscles and pass into other animals to complete their final metamorphoses. Many Cercariae appear to prefer the larvae of insects whose bodies they en- ter by means of their cephalic hooks. In this way I have seen the Cercaria armata easily enter the larvae of Ephemera, Nemura,and Perla. By the aid of its sting it can perceive the intersegmental membrane of these larvae. Frequently it loses its tail in passing through a narrow opening it has made. Immediately upon reaching the cavity of the body of the larva, it is surrounded by a vesicular membrane, in which the sting is rejected, and the animal enters upon its final metamorphosis. But I have a doubt whether it is there completed, for among the numerous similar parasites which I have found in the most different insects whose larvae are *[§ 118, note 7.] In this connection should be noticed the remarkable phenomena of reproduction with Gyrodactylus as recently observed by Sie- bold (Siebold and Kélliker’s Zeitsch. I. 1849, p. 345). Individuals are here developed viviparously as in the so-called alternating generations, and Siebold has observed a mother in which was a daughter and in this last a grand-daughter, the series being therefore three-fold. These viviparous individuals contain no sexual organs proper, but the new individual is developed out of a group of cells situated within the body. The whole repro- ductive conditions which Siebold has detailed with his usual care appear to me to closely resemble those of the viviparous Aphides which I have different ways: Hither the embryo- aquatic, as of Libellula. Agrion, Ephemera, and Phryganea, I have never met with one whose genital organs were in astate of advanced deyvelop- ment. The full development of these organs, the deli- cate contours of which may be seen while the par- asites are in the bodies of these animals, is not perhaps attained, until the insects have been swallowed by birds and other animals, — being thereby furnished with more proper conditions for their complete formation. Some Cercariae lose their tail and are surrounded with a capsule without leaving the Mollusks which are their first habitat. This is probably so, be- cause these Mollusks are liable to be eaten by aquatic birds, in which these parasites may prop- erly reach their final development. It should, however, be remarked that when these larvae be- come chrysalides, their investing capsule or cyst, is a secretion from their bodies, and not a product of the animals in which they live. It is probable that very many of these larvae never attain a per- fect state, for, in their migrations, they fail to reach their destined and final habitat. These migrations undoubtedly occur with many Cestodes while young ; at least Miescher (log, cit.) has observed it with T'etrarhynchus. But although we have followed these in their migrations, and the transformation of many of them into Monostomum and Distomum has been observed, and therefore the completion of their metamorphoses, yet we are but slightly informed as to their beginning by the alternation of generation. e There is yet little known as to the manner in which these embryos are changed into the cylin- dric nurses. There are now only two isolated facts throwing light upon this point. According to my own observations (Wiegmann’s Arch. 1835, I. p. 75, Taf. I.), each embryo of Monostomum mutabile contains a germinative tube, which, at the death of the embryo, is freed and quite resem- bles the nurse of Cercaria echinata. I have also observed in the embryos of Amphistomum sub- clavatum a tubular body, but I could not satisfy myself of its germinative nature. According to Steenstrup (loc. cit. p. 98), there is an animal like a Paramaecium, and probably an embryo of a Distomum, living in Muscles, and which finally is deprived of its epithelium, and changed into the rigid, germinative tube of Distomum duplicatum ; see upon this, my Jahresbericht in Wiegmann’s Arch. 1843, IL. p. 300.* recently investigated ; and I believe this mode of reproduction to be only a peculiar form of gemmi- parity or budding suited to some ulterior, econom- ical purpose of the animal’s life. On afutwre page I shall speak more fully on this point and attempt to show that the whole set of phenomena known under the name of “ Alternation of Generations” is, when divested of its paraphernalia, only a kind of Gemmiparity. See also for further details on that curious ani- mal Leucochloridium paradoxum, Piper, in Wiegmann’s Arch. 1851, I. p. 318, but especially Siebold, in Siebold and Kélliker’s Zeitsch. IV. 1853, p. 425, Taf. XVI. B. This last-named ob- server has shown that this animal form is only a $ 119. THE HELMINTHES. 131 nic cells present the same successive phases as in the Cestodes and Trema- todes, without the appropriated vitellus undergoing any segmentation ; or, the whole vitellus after a complete segmentation, is changed into an em- bryo. In both cases, the embryo has the parent’s form. A muscular cesopha- gus and straight intestine appear in its body in the midst of the refuse vitelline granules; and thus the young animal attains its perfect state by simple increase and by the development of its genital organs, but without any metamorphosis. From the few observations hitherto made upon the development of the Gordiacei, it appears that the embryos exactly resemble the parents. 1 Kélliker was the first to call the attention to these two types of development with the Nema- todes (Miiller’s Arch. 1843, p. 68, Taf. VI. VII.). With Ascaris dentata, Oxyuris ambigua, and Cucullanus elegans, free embryonic cells are formed in the vitellus without its fissuration. But there is a complete segmentation with Ascaris nigrovenosa, acuminata, succisa, osculata, labiata, and brevicaudata, Strongylus auricu- laris, dentatus, Filaria inflexo-caudata, rigida, and Sphaerularia bombi. After I had already noticed this vitelline segmentation with the Ne- matodes (Burdach’s Phys. loc. cit. p. 211), which Bagge (Dissert. loc. cit.) described very fully, Kalliker (loc. cit.) attempted to reconcile it with the cell-theory, by regarding the cells which appear in the segmented, vitelline globules, as the embryonic cells, and in the multiplication of which by segmentation, the enveloping vitellus participates. 2 It appears that, as with the Trematodes, so in the Nematodes, a migration of the young precedes their complete development. In the tissues of the most different insects and vertebrates, there are found small Nematodes without genital organs, and contained in a cyst. They could not get there except by a migration, and they cannot attain the full development of kind of nurse of a Distomum, containing peculiar germ-bodies which are developed into Distomum. But the most important result obtained is that all Distomum are not developed by means of a cer- carian, larval stage,— the economy of some making it seemingly requisite that the developmental pro- cess should be more direct. — Ep. * [§ 119, note 2.) In regard to T'richina spi- ralis, the various researches upon its structure, made in England and America, would show that it is a true animal having genital organs. The fol- lowing are some of the references upon this sub- ject: Owen, London Med. Gaz. April and Decem- ber, 1835, or Transact. Zool. Soc. London, IV., or Cyclop. Anat. and Phys. Art. Entozoa; Wood, London Med. Gaz. May, 1835; Farre, Ibid. De- cember, 1835; Harrison, Report of the Brit. Assoc. for the Advancem. of 8c. 1835 ; Knox, Edinb. Med. and Surg. Jour. 1836, XLVI. p. 86; Hodg- their genital organs or their bodies in general, except through a transplantation upon other ani- mals ; exactly as occurs with the trematodal larvae. (See the observations of Creplin and myself upon the sexless Trematodes, in Wiegmann’s Arch. 1838, I. p. 302, 373.) The T'richina spiralis of man is undoubtedly an encysted and imperfect form of one of the Nema- todes, and in which one may seek in vain for gen- ital organs. Some of these Nematodes appear to increase in their cysts without their genital organs being developed in the same proportion. Thus, the Filaria piscium are sometimes found very large, while their genital organs are very little developed ; and these last do not probably attain their perfect state, until, as with Bothriocephalus solidus, these worms have passed into other animals. For the same reason, I agree with Steenstrup (loc. cit. p. 115), who doubts that the Filaria piscium become, as Miescher has affirmed (loc. cit. p. 26), a globular capsule out of which there afterward appears an animal at first resembling a Trema- tode, but which finally becomes a Tetrarhyn- chus.* 3 See Dujardin (Ann. d. Sc. Nat. XVIEI. loc. cit. Pl. VI. fig. 15, 16) upon Mermis nigrescens, researches which I have been able thoroughly to confirm. kin, Lect. on Morbid Anat. of Serous and Mucous Membranes, I. p. 212; Curling, London Med. Gaz. February, 1836 ; Bowditch, Boston Med. and Surg. Jour. April, 1842; Luschka, Siebold and Kélliker’s Zeitsch. III. 1851, p. 69, Taf. III., and Gairdner, Edinb. Monthly Jour. of Sc. May, 1853. The subject is one that deserves especial attention from Helminthologists. — Ep. t [§ 119, note 3.] Grube (Wiegmann’s Arch. fiir Naturgesch. 1849, p. 358) and Leidy (Proc. Acad. Sc. Philad. V. 1850, p. 98) have observed the development of Gordius. It corresponds pretty closely with that of Ascaris as described by Bagge ; but the embryo on escaping from the egg is annulose and tentaeulated, and differs much from the adult form. Nothing is known of the history of the animal between these two conditions. — Ep. - BOOK SIXTH. TURBELLARIA. CLASSIFICATION. § 120. THe TurBELLARIA receive their name from the ciliated epithelium, which covers their whole body. Their flattened, or cylindrical, non-articulated body, is formed of a loose parenchyma, in which lie hid the viscera. The nervous system appears very little developed, and when visible, consists only of a cervical ganglion, from which there never extends a ventral cord. The multiramose intestinal canal is always without an anus. The genital organs are either very much developed, or entirely absent.” In the first case, these animals are always hermaphrodites, and have copulatory organs. The Turbellaria have been shifted from one zoological system to another, but their organization has sufficient peculiarities to entitle them to a special class by themselves. Ehrenberg was the first to found the group Turbellaria; but he has in- cluded therein many different animals; and we are, eretane, indebted to Orsted, for a late revision of this group. ORDER I RHABDOCOELL The alimentary canal is simple and cylindrical; the oesophagus, non- protractile ; locomotion, mostly natatory. Genera: Vortex, Derostomum, Gyratriz, Strongylostomum, Mesostomum, Typhloplana, Macrostomum, Microstomum. ORDER II. DENDROCOELL Intestinal canal dendritically ramified ; oesophagus completely protrac- tile; locomotion reptatory. 1 I cannot here omit the question, if these small era, and if they are not rather the larvae of other sexless Turbellaria, as for example, Derostomum, _ inferior animals. and Microstomum, really constitute distinct gen- $ 121. THE TURBELLARIA. 133 Genera: Polycelis, Monocelis, Planaria, Leptoplana, Eurylepta, Planoce- ra, Thysanozoon. BIBLIOGRAPHY. Baer. Ueber Planarien, in the Noy. Act. Acad. Leop. XIII. 1826, . 691. ; Dugés. Recherches sur l’organisation et les moeurs des Planariées, in the Ann. d. Se. Nat. XV. 1828, p. 189; and XXI. 1830, p. 72. See Isis 1830, p. 169, or Froriep’s, Not. 1829, No. 501. Mertens. Ueber den Bau verschiedener in der See lebender Planarien, in the Mém. de l’Acad. de St. Petersbourg, 6°"* Sér. Tom. IT. 1833, p. 1. Ehrenberg. Phytozoa turbellaria, in the Symbolae physicae, Ser. I. 1831. , Focke. Ueber Planaria Ehrenbergii. in the Ann. des Wiener Mus. I. Abth. 2, 1836, p. 193. F. F. Schulze. De Planariarum vivendi ratione et structura penitiori nonnulla. _ Dissertatio. Berolini, 1836. A. S. Orsted. Entwurf einer systematischen Eintheilung und speciel- len Beschreibung der Plattwurmer. Copenhagen, 1844. ADDLEE ON A bin Bil Bart O1G RA PHA, : Beside the writings referred to in my notes, see the following: Schmidt. Die rhabdocoélen Strudelwtirmer des siissen Wassers. Jena, 1848. Neue Beitrage zur Naturgesch. der Wurmer. Jena, 1848. Erster Abschnitt, Turbellarien. Handbuch d. vergleich. Anatomie, 1849, p. 294. M.S. Schultze. Ueber die Microstomeen, eine Familie der Turbellarian, in Wiegmann’s Arch. 1849, p. 280, Taf. VI. Beitrage zur Naturgeschichte der Turbellarien. 1851.— Ep. CHAPTER I. CUTANEOUS SYSTEM. § 121. The whole body of the Turbellaria is covered with ciliated epithelium, under which lies a loose cellular parenchyma. In this parenchyma, and directly beneath the epithelium, there are found, in many species, particu- lar cell-like bodies, which sometimes remind one of the nettling organs of certain zoophytes, and sometimes exactly resemble the prehensile organs 12 134 of the arms of Polyps.” THE TURBELLARIA. § 122. These bodies contain six or eight, or even more, staff-like, colorless corpuscles, which are parallelly arranged side by side, or curved a little spirally. With their further development, the envelope disappears, and they then remain free under the skin, but sometimes pro- jecting through it. CHAPTER fI. MUSCULAR SYSTEM AND LOCOMOTIVE ORGANS. § 122. Although their parenchyma is extremely contractile, yet the Turbellaria have only a very feebly-developed muscular system. In many small species of the Rhabdocoéli, the parenchymal muscles may be made out; and in the larger Planariae, when the muscles are visi- ble, their fibres appear unstriated. The small Rhabdocoéli swim by means of their ciliated epithelium, like many Infusoria, their bodies revolving on its longitudinal axis; while the flattened Dendrocoéli crawl along like the Gasteropoda.” Many larger species of the first order,” appear to float from place to place by means of their epithelium, thus really neither creeping nor swimming. 1 With Microstomum. lineare, Orsted, these prehensile organs so closely resemble those of Hydra that they need not be described, According to Orsted they are urn-shaped glands in the centre of which are parabolic bodies which are constantly in motion (loc. cit. p. 73, Taf. IL. fig. 18). But had he pressed these organs between two plates of glass, he would have seen the protruding filament, together with its double hooks. 2 [have seen these corpuscles protruding through the lateral border of the body of Planaria lactea. In the dorsal papillae of Thysanozoon Diesingii, a part of these corpuscles are contained in cells ; but the others are free and often protrude through the skin. With Mesostomum Ehrenbergii, and rostratum, they are arranged in rows in the anterior half of the body, forming striae, which quickly catch the attention. Orsted has taken these: corpuscles for as many muscular columns (loc. cit. p. 70, Taf. II. fig. 26, 37). The spines which, according to him (loc. cit. p. 72, Taf. II. fig. 29, 34) cover the entire surface of Macrostomum hystria, are probably of the same nature, as may also be said of the delicate short bristles found everywhere under the skin of Derestomum leu- cops, Duges. Quatrefages, in his monograph on marine Planariae (Ann. d. 8c, Nat. TV. 1845, p. 146, Pl. VII. fig. 9, 10), also mentions various formations which, partly as spines, partly as nettling or- gans, are found in the skin of certain Dendrocoéli. 1 The mode of locomotion by which these animals move over solid bodies, or upon the surface of the water, has not yet been satisfactorily explained. The ciliated epithelium cannot here be the principal agent. According to Schulze, loc. cit. p. 32, the staff-like corpuscles projecting from the back of these animals, and which he terms bristles, are used as oars. According to Mertens (Mém. de l’Acad. de St. Petersbourg, 6e™me, sér. Il. 1833, p. 5), Planaria lichenoides moves by means of the protruded lobes of its pharyngx. 2 For example, Mesostomum. $$ 123, 124. CHAPTERS IIT. THE TURBELLARIA. 185 \ AND