ALBERT R. MANN LIBRARY New York STATE COLLEGES OF AGRICULTURE AND HoME ECoNoMICS AT CoRNELL UNIVERSITY Corneil University Library QL 363.S57 | mi ini 3 1924 0 Cornell University Library The original of this book is in the Cornell University Library. There are no known copyright restrictions in the United States on the use of the text. http://www.archive.org/details/cu31924003418229 ANATOMY OF THE INVERTEBRATA bark Sherdgr Synat vin TH. y SIEBOLD, Translated from the German with Additions and Notes BY WALDO I. BURNETT, M.D. BOSTON: JAMES CAMPBELL, 18 TREMONT STREET. 1874. (ees eee pee nel / CORNELL » (university \ LIBRARY 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. Entered according to Act of Congress, in the year 1874, by JAMES CAMPBELL, In the Office of the Librarian of Congress at Washington. PRINTED BY J. E. FARWELL & COQO,, 34 MERCHANTS Row, BOSTON. Zo MY ESTEEMED FRIEND, LOUIS AGASSIZ, PROFESSOR OF ZOOLOGY, &o., In Harbarh Wnibersity, WHOSE WELL-KNOWN RELATIONS TO COMPARATIVE ANATOMY REQUIRE WO MENTION HERE, AND WHOSE SPLENDID GENIUS HAS DONE SO MUCH TO AWAKEM, IN THIS COUNTRY ESPECIALLY, A LIVELY INTEREST IN OBJECTS OF NATURAL HISTORY, O Auscribe this Volume, WITH ADMIRATION AND SINCERE GRATITUDE, WALDO I. BURNETT. PUBLISHER'S NOTICE. For some years there has been a constant and increasing demand for a thorough and reliable text-book on the Anatomy of the Invertebrata ; and no other book having appeared upon the subject to meet the requirements and to supersede Dr. Burnett’s translation of Von Siebold’s Lerhbuck der vergleichenden Anatomie, which, to- gether with the translator’s valuable and extensive notes, is believed to be incomparably the best and most complete treatise on the science, and the same having been highly commended by Professors Agassiz, Silliman, Hitchcock and others, the publisher feels him- self justified in offering this edition to the student, confident that it will supply a want not at present met by any other work in our lan- guage. Boston, May, 1874. NOTICE OF THE TRANSLATOR AND EDITOR. In issuing an English translation of the Lehrbuch der ver- gleichenden Anatomie of Von Sr1esoLD and SrTannivs, 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 from all other treatises of the kind that have preceded it. In the text will be found a lucid yet succinct exposition of tha 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 Stebold has said in his preface, the anatomy of these lower forms is scarcely reliable unless based upon histological investigations. VIII 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 hag 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, I 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. Edward 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 honurably recorded by their own important labors in science, to which I have so frequently referred in these volumes. WwW... B. 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,.&s , 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 I 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 miné 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 (IN Breiseau), Feb. 27, 1848. C. Tu. v. SIEBOLD. TABLE OF CONTENTS. Classification of the Invertebrate Animals,. « . 2 eee eee Bibliography, « «se ee eee eer cere ere rseee Introductory Note to the Infusoria. I, THE INFUSOBIA AND RHIZOPODA. Classification and Bibliography,- « » « 1, External Covering, . . ig eS o-. 2. Muscular System, and Locomotive Organs, 8, 4. Nervous System, and Organs of Sense, 5. Digestive Apparatus, 2... s+ ee 6, 7. Circulatory and Respiratory Systems, 8, Organs of Secretion,. . . . 22 +> 9. Organs of Reproduction,. . . . » « Introductory Note to the Zoophyta. Il. THE POLYPI. Classification and Bibliography, «+» -s+« « © 1, Cutaneous Envelope and Skeleton,. . .. . 2, Muscular System, and Organs of Locomotion, 8, 4. Nervous System, and Organs of Sense, . 5. Digestive Apparatus, . . 2+ 2 eee Digestive Cavity of the Anthozoa, . . . Digestive Cavity of the Bryozoa, ... 6, 7. Circulatory and Respiratory Systems, . 8. Organs of Secretion,. . 2. see ee 9. Organs of Generation, . .» 2+ s+ . ° ° . . . . eer eevee . e . . . . . e . . eee eee ew eae eeeree eee “ -I0. THE ACALEPHAE. Classification and Bibliography,» » « « «.« 1. Skin and Cutaneous Skeleton,. . . » ee ee 2. Muscular System, and Organs of Locomotion, . 8. Nervous System, 4, Organs of Sense, ibe (0) 6: coi ve se: ia ey ce 5. Digestive Apparatus, 6. Circulatory System, - 7, Respiratory Bystem, . 0.0 sacs cee ew ee ee ewe eee eevee ere eee ee coe eee ee eee SECTION XII 8. Organs of Secretion, 9. Organs of Generation, . . .» ODOT Hp od ee © GOTH Sup oo bo ee PCoOronpnre Classification and Bibliography, . . . Cutaneous Envelope and Skeleton, - . . Muscular System, and Organs of Locomotion, . . . . . Nervous System, ‘ . Organs of Sense, . . Digestive Apparatus, Circulatory System, . . Respiratory System, . . Organs of Secretion, . Organs of Generation, Classification and Bibliography, . Cutaneous System, . . . Muscular System, and Organs of Locomotion, . Nervous System, Organs of Sense, . Digestive Apparatus, . Circulatory System, Respiratory System, . Organs of Secretion, . - . Organs of Generation, . Classification and Bibliography, .. .« . Cutaneous System, . . Muscular System, and Locomotive Organs, . . Nervous System, and Organs of Sense, . . Digestive Apparatus, Circulatory and Respiratory bc amed . Organs of Secretion, . Organs of Generation, . . Classification and Bibliography, . . Cutaneous System, Muscular System, and Locomotive Organs; eu . Nervous System, and Organs of Sense,. . . Digestive Apparatus, Circulatory and Respiratory Systems, . Organs of Secretion, . see Classification and Bibliography, . . Cutaneous System, . CONTENTS. Iv. THE ECHINODERMATA Muscular System, and Locomotive Organs, «+... .. SECTION ee i Bh wh ee ee, Gel 65 Sigheiiel acl uae decent sata ara:. (OG270 shea hee aleal feast “GI ah hte al Bisse avis eo wie a a OPER TB See eae 2 1678 cS So eo wh ina a Be we 99280 Sain ee ew Sa Giahe sols Bee 81 Sime goede a qs a8 Sle eects 82-86 te ee ee ee 87-88 Nis Sap dao jel cey ah Carchad. tet eyo a eee eee ew ee 689-98 Bsc GaGn thay thus. ee erat aa a3 fe ; 94 Ble nay ad tea) We Pa ods e wile te es) 106298 VY. THE HELMINTHES. arias Tas Bc Macy os er a 99 Bob . aouelss ihn ae oe ee OOO oe Be 3 ee eee © 102-108 eee ee wine ae 104 ee ce a Bs eae 6 208 iene ee sae «6106-109 eat oie oad te ew LLOSTET oe eH 8 8 we we 112 era a he! eo fer te ww 113 Se ea ae a eR T19 VI. THE TURBELLARIA, tee RHR DED © & 120 aa ee ae 121 eee ee eS PS ie ables eh ah de cit ios ans we DBT Gita tal airehe evutiwery. | aOR se Tate ete Keel GEL Shahar 126 Bana Belie wee sig op ohtes da wae eyo AT . see ee 6 128-129 VI. THE ROTATORIA. CRE Saaee: F180 5 gy “efias eee : ree i) ios wiles a Gis vo LBD=TBS 8 esi a oo 184-185 eae yi cue YI ‘tHe ANNELIDES. 3 SO Yee ah 142 (eee eM we Be 143 wee 144-145 CONTENTS. 8. Nervous System, «+--+ see ee en etre 4 Organsof Sense, . 2-2-1 eee eee ee ene I. Organs of Touch,. .. 2. + ee ewe veee IL Organs of Vision, . 2... 1... ee ee eee III, Organs of Hearing, »... 1-224 eee 5. Digestive Apparatus, . . Pee er ae I. Organs of Deglutition and Mastication, Bae! 2a te YS II. Intestinal Canal,. . 1 2s we ee ee we wwe III, Glandular Appendages, . 2... 0.000 6. Circulatory System, . 2... +e ee eee eae 7. Respiratory System, .. 1... + see eee ene 8. Organs of Secretion,. 2... 6 2 2 se eee ee 9. Organs of Generation,. . 2 2 6 ee ee ee ee Ix. THE ACEPHALA. Classification and Bibliography,. ........4- 1. Cutaneous System, .. 1.1.1 es we ee eae 2. Muscular System, and Organs of Locomotion,. ... 8. Nervous System, . 1... 2 ewe ee eee nee 4. Organs of Sense, . 2... ee ee eee tees 5. Digestive Apparatus, BoBC OR TRL se! HOSEN ar See 6 Circulatory System, . 2... 6 ee ee ere eae 7. Respiratory System,. . 1. 2s we se ee ee 8. Organs of Secretion,. +... +... ee eee ae 9, Organs of Generation, ... 2... ee ee eee X. THE CEPHALOPHORA. Classification and Bibliography,. .... +. ..6+ 1, Cutaneous System, ...... & Be he Ks 2. Muscular System, and Organs of Locomotion, Chr oe 8. Nervous System, . 2... ee ee ee eee 4, Organs of Sense, . 2.2 1 ee ewe ee wee 5. Digestive Apparatus, . 1... 2 eee eet eee 6. Circulatory System, . . 2. 1 1 ee ee ee eee 7. Respiratory System, .. 2... + ee eee eee T,, Branchiae;,. ay 2) ao ses fener ye alee eRe Be TE Lungs: se: 6 sar ep eo eos go) ve Ee ka ee BGP Ga ea III. Aquiferous System, . . 2.2 e+. ee eee 8. Organs of Secretion,. . 2 2. 2 ee ee et ee I. Urinary Organs, . - ee ee ee tee ee II. Organs of Peculiar Secretions,. .......-. 9. Organs of Generation, ........- aaa Sr fe XI. THE CEPHALOPHODA. Classification and Bibliography,. ..... + +e 1. Internal Skeleton,. . 2... 1 2 eee eee ae 2, Cutaneous Envelope, .. 1. ee ee eee eae 8. Muscular System, and Organs of Locomotion,. ... 4, NervousSystem, 2. + ee es eee een eee 5. Organs of Sense, «0 6 ee eee ee ee es 6. Digestive Apparatus, . 2. 2 ese ee eevee 7. Circulatory System, . 2 + 0 se ee ee eee 8. Respiratory Organs,. . 2 2 2 +e ees ee eee 2 ee rT ee © © & ow ww XIItr SECTION 146-148 198-195 196 - 197-200 201 202-2038 204-205 206-209 - 210-212 213-215 216-218 219-222 220 221 222 223-224 223 224 + 225-229 280 - 231-232 + 233-235 + 236-238 » 239-242 « 248-247 » 248-260 - 251-552 - 2538-254 XXIV 9 10. WITH Op po does > BMAP TP ONHE MAD ow oboe . Digestive Apparatus, . Circulatory System,...... . Respiratory System, ...... . Organs of Secretion, . . Digestive Apparatus, . . . Circulatory System, ..... Sy Fen a= cae SS . Respiratory System,. . 2. 6 2 6 ee ee ee ee . Organs of Seeretion,. . .... Sie el et . Organs of Generation, . . . CONTENTS. Organs of Secretion,. . . + . « I, Urinary Organs, ...... II. Organs of Special Secretions, Organs of Generation,. . . « « Introductory Note to the Crustacea. XII. THE CRUSTACEA. Classification and Bibliography, er ae ee External Envelope, and Cutaneous Skeleton, Nervous System, .... 2.2... Organs of Sense, ....... I. Urinary Organs, II. Organs of Special Secretions, . ee eo eye Organs of Generation, ........- I. Hermaphrodite Crustacea, .. . JI. Female Crustacea, ...... III. Male Crustacea; . ee ee ew ew . Muscular System, and Organs of Locomotion, . . . . . eo . . . . XUI. THE ARACHNOIDAE. Classification and Bibliography, . . Organs of Sense, .....-- ae I. Urinary Organs, II. Organs of Special Secretions, I, Hermaphrodite Arachnoidae,. . TI. Female Arachnoidae,. .. . III. Male Arachnoidae, XIV. THE INSECTA. Classification and Bibliography, . . Organs of Secretion,. .. .. - I. Urinary Organs, ... . II. Organs of Special Secretions, Organs of Generation,. . . . . I. Female Genital Organs, .. . If. Male Genital Organs, Tndex,... . External Envelope, and Cutaneous Skeleton, Muscular System, and Organs of Locomotion, . Nervous System, . External Envelope, and Cutaneous Skeleton, . Muscular System, and Locomotive and esas Organs, . Nervous System, ...-. +e. . Organs of Sense, ... +... . Digestive Apparatus, ..... . Circulatory System, ...... . Respiratory System,. ..... Swe es we er ee rd Ce ee eee ey ee eee ee ee Pr er ee ee ee wee ee SECTION 257-261 . 262 « 263-266 . 267-269 - 270-278 CLASSIFICATION OF THE INVERTEBRATE ANIMALS. 8 § 1. Tux 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. Crass I. Inrusorra. Cuass II. Rutzopopa. 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 oesophagus. Crass III. Potyrr. Cuass IV. AcaLerua. Quass V. Ecninopermata, 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. Crass VI. Hetminvues. Crass VII. TourseLvari. Crass VIII. Rorarortz. Crass IX. ANNOLATI. 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. Crass X. ACEPHALA. Crass XI. CrpHaLornora. Crass XII. Cepuatopopa. FIFTH 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. F Crass XIII. Crustacea. Ciass XIV. Aracunipa. Cuass XV. Insecta. BIBLIOGRAPHY. § 2. 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. Gét- tingen, 1824. 2Lecons d’Anatomie comparee. Paris, 1799- 1805. Translated into German and published with notes and additions by Meckel and Froriep. 4 vols. Leipzig, 1809-10. 2nd edit. Paris, 1835-45. System der vergleichenden A i Halle, 1821-33. 4 Lectures on Comparative Anatomy. 6 vols. London. 1814-29. 6 vols. 5 De l’Organisation des Animaux, ou Principes d’Anatomie comparée. Tom. I. Paris, 1832. : 6 Tstituzioni di Anotomiae Fisiologia © Napoli, 1832. 7 Lehrbuch der vergleichenden Anatomie. 2nd ed. Leipzig, 1834. ; eo of Comparative Anatomy. London, * A General Outline of the Animal Kingdom, and ie lof ive A y. London, 1841. parata. $ 2. BIBLIOGRAPHY. 17 Dirckheim, 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. Delile Chiaje.—Memorie su la Storia e Notomia degli Animali senza Vertebre del regno di Napoli. 4 vol. Napoli, 1823-49. 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. I-CLXXII. Sars. — Beskrivelser og Jagttagelser over nogle moerkelige eller nye t 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. — Elémens de Zoologie, ou Lecons sur |’Anatomie, la 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 dek Prof. G. Meneghini. Venezia, 1847. Con tavol, I-XVI. Deux. 0 Traité pratique et théoretique d’Anatomie om, . 2vol. Paris, 1842. 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; Erschei und Gesetze des organischen Le- bens. 2vol. Bremen, 1831-33. 18 Grundriss der Physiologie. 1821-28. . 14 Praité de Physiologie comparée de "Homme et des Animaux. 3 vol. Montpellier, 1838-39. 16 Die Physiologie als Erfahrungswissenschaft, erste Aufiage, mit Beitragen von C. v. Baer, Dieffenbach, J. Muller, R. Wagner. 6 vol. Leipzig, 1826-40. 2 te Auflage, mit Beitrfigen 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. 2 vol. Berlin, 2% VW Lehrbuch der Physiologie. 2nd edit. Leipzig, 1843 Berlin, 1829-33. 18 Medicinische Zoologie. 2 vol. i Anato- 19 Erla@uterungstafeln zur vergl mie. 6heft. Leipzig, 1826-43. 20 Icones physiologice. Erlduterungstafeln zor Physiologie und Entwickelungsgeschichte. Leip- zig, 1839. Also, Icones Zootomice. Handatlas zur vergleichenden Anatomie. Jeipzig, 1841. 2% Iconographie du Régne Animal de G. Cuvier, ou Représentation W’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, 1830-38. 2 Régne Animal de Cuvier, nouvelle édition, ac~ compagnée de planches gravées, &c. &. Paris 1836-47. Still unfinished. INTRODUCTORY NGTE 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 2 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 Kolliker t 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 Kélli- ker’s view of a stomachless animal prove correct, the inverse condition of 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. Stebold, Kolliker, 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- uae.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 + has raised the point of their belonging to the Worms. But, aside from such grounds, I was led, somestime since, after considerable study of infusoria-forms, to veuture an opinion quite at variance with that just mentioned of Szebold and Kciliker. 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 much, — 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. Siebold and Kélliker’s Zeitsch. + Bruch. Siebold and Kélliker’s Zeitach. I. p. 270. IL. p. 110. + Kélliker. Siebold and Kélliker’s Zeitsch. § Burnett. Proceed. Boston Soc. Nat I. p.1. Hist. V. p. 124. BOOK FIRST. INFUSORIA AND RHIZOPODA. CLASSIFICATION. § 3. Tux 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 off the so-called Polygastrica. In fact, a great number of the forms included under OClosterina, 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, &¢., 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 che earlier forms of many conferve,® in which last can 1 Mikroskopische Untersucl , &c. Berlin, teurs des spores des Algues. Ann. des Sc. Nat 39 Botan. 1843, XIX. p. 266, Pl. XI. fig. . 2 Thuret. Recherches sur les organes locomo- 8 The same. Pi. X. ee $$ 4, 5. 21 often be seer. 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 Bacillareee 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 Naviculz can protrude ciliary locomotive organs through openings of their carapace ; but this has not been observed by other naturalists. 4 INFUSORIA AND RHIZOPODA. § 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 Also, Kitzing, Ueber die Verwandlung der 4 Asan may be d the various Infusorien in niedere Algenformen. Nordhausen, and dissimilar opinions of naturalists upon the 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 Nov. Act. Acad. Leop. Carol, vol. XX. part ii. . 18. e 5 See Unger, Die Pflanze im Momente der Thierwerdung. Wien. 1843. 1844. In an academic paper (Dissertatio de finibus inter regnum animale et vegetabile constituendis, Erlangae, 1844), I have attempted to show that this confusion between the two kingdoms does not exist. 6 Abhandl der Akad der Wissen- schaften zu Berlin, 1836, p. 134, Taf. I. fig. 19, and 1839, p. 102, Taf. IV. fig. 5. 22 INFUSORIA AND RHIZOPODA. $e orders, Anentera and Enterodela, appears unfounded, the following class- ification seems more natural : ; PROTOZOA. Cuass INFUSORIA. Organs of locomotion chiefly vibratile. ORDER I. ASTOMA. Without an oral aperture. Famity: Astastaza. Genera: Amblyophis, Euglena, Chlorogonium Faminy: Prana. Genera: Peridinium, Glenodinium. Famity: Opatinara. Genus: Opalina. ORDER II. STOMATODA. With a distinct oral aperture and cesophagus. Famity: VorticELLina. Genera: Stentor, Trichodina, Vorticella, Epistylis, Carchesium. Famity: Oparypina. “Genera: Vaginicola, Cothurnia. Faminty: Encwerta. Genera: Actinophrys, Leucophrys, Prorodon. Famity: TRACHELINA. Genera: Glaucoma, Spirostomum, Trachelius, Loxodes, Chilodon, Phialina Bursaria, Nassula. Famity: Koxpopga. Genera: Kolpoda, Paramecium, Amphileptus. Famity: Oxytricuina. Genera: Oxytricha, Stylonychia, Urostyla. Famity: Evuptora. Genera : Euplotes, Himantophorus, Chlamidodon, $ 5. INFUSORIA AND RHIZOPODA. 23 Cuass RHIZOPODA. Organs of locomotion consisting of completely retractile, ramifying prolongations of the body. ORDER I. MONOSOMATIA. Famity: AMOEBAEA. Genus: Amoeba. Famity: ARCELLINA. Genera: Arcella, Difiugia, Gromia, Miliola, Euglypha, Trinema. ORDER II. POLYSOMATIA. Genera: Vorticialis, Geoponus, Nonionina.™ BIBLICGRAPHY O. F. Miller. Animalcula Infusoria. Hafniee, 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. Llustrated by nearly 800 colored engravings of these curious creatures, highly magnified. London, 1841. Kutorga. Naturgeschichte der Infusionsthierchen, vorztiglich nach Eh- 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 Siebold & Kolliker’s Zeitsch. III. Hft. 3, and IV. Hft. 3. Ecker. Zur Entwickelungsgeschichte der Infusorien, in Siebold & Kdl- 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.— Ep. 1In 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 CHAPTER I. EXTERNAL COVERING. § 6. The Prorozoa are surrounded by a very delicate cutaneous envelopes 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 II. 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. Tus Visratite Oreans on the surface of Infusoria serve as organs of locomotion. j With many species they are found much developed at certain points, and are arranged in a remarkable order and manner. With Peridiniwm, 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 Trichodina 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 T'richodina 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. 3 Amphileptus, Chilodon, Opalina, &c. 2 Ehrenberg has entirely overlooked the ciliated 1The peduncle is simple with Vorticella, but border of Trichodina pediculus, and bas regarded ramified with Carchesium. With Epistylis it is the stiff serrations of the ring as movable hooks. ot muscular, See “Die Infusionsthierchen,” p. 206. $$ 9, 10. 25 tical action of the water. But with others the locomotive organ is a long retractile proboscis.” With the Oxytrichina and Euplota, there are fleshy 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 in the other genera they are elongated and filamentous. INFUSORIA AND RHIZOPODA. t CHAPTERS III. AND IV. 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 necessarily 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 8 Amblyophis, Euglena and Peridinium, have 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 strigilata, Euglypha tuberculosa, Tri- nema acinus, according te Dujardin (Ann. des Se. Nat. Zool. IV. 1835, p. 343, pl. IX.; also, V- 1836, p. 196, pl. IX. fig. A. See, also, his Histoire des Infusoires, 1841, p. 249, pl. I. fig. 14-17; pL II. fig. 1, 2, 7—10 ; pl. TV. fig. 1); Geopvonus stel- la borealis, Nonionina germanica, according to Ehrenberg. Abhand. d. Berliner Akad. 1839, p. 106, Taf. I. IL. 1 Amblyophis, Euglena, Chlorogonium, &c. 2 AbhandJ. d. Berliner Akad. 1831, p. 12; alsc, “ Die Infusiousthierchen,” p 491. 26 $$ 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.* INFUSORIA AND RHIZOPODA. CHAPTER V. DIGESTIVE APPARATUS, § 11. 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 eonnection 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 Opaline 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 ag 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 cav- ities. In many cases there is at the end of the body opposite the mouth an anvs, through which the refuse material is expelled. But, when this is 8“ Die Infusionsthienzhen,” p. 492. 1 Auserlesene mikroskopische Entdeckungen, 1777, p. 51; also, Abhandlung iiber die Saamen- und Infusionsthierchen, 1778, p. 140. * Some recent researches of T'huret (Ann. d. Sc. Nat. 3rd 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 th yes and germi pr ds. The 2The genus Opalina was first established by Purkinje & Valentin. Many species are found in the rectum of frogs, and itis not rare to meet with them in the alimentary canal of Planarieae.t fact is a very interesting one in this connection. — Eb. +[§ 11, note 2.) According to Agassiz (Amer. Jour. Sc. XIII. 1852, p. 425), Opatina is only & larval form of Distoma. — Ep. § 12. oT 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 msophagus, 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 oesophagus, 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 an 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. i 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 Amada, Arcella and Diffiugia, it appears that the Rhizopoda ‘ingest their food like the Stomatode Infusoria, INFUSORIA AND RHIZOPODA. neck. ( Miiller’s Arch. 1839, p. 80; also Monats- bericht der Berliner Akad. 1841, p. 103.) But, de- tailed as they may be (see Ehrenberg Abhandl. d. Ber. Akad. 1830, Taf. IfI.; 1831, Taf. III.; also “Die 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. TV. 1835, p. 364; V. 1836, p. 193; X. 1838, p. 280; also Hist. Nat. des Infus. 1841, p. 57), in Meyen (Miller’s Arch. 1839, p. 74) and in Ry- mer Jones (Ann. of Nat. Hist. ITI. 1839, p. 105 5 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, 1858, p. 341) has recently published an t, panied 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 Infusionsthierchen,” Taf. XXXII. XXXVI. and XXXIX.), they are not representations of nature. The organ whichin Trachelius ovum has been taken by Ehrenberg (“Die Infusionsthierchen,” p. 828, 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 ta internal pressure, and so small as to be microscop- ic ; this bag, filled with particles of sand, shells of INFUcORIA AND RHIZOPODA. $$ 18, 14. 28 § 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 Trachelius 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, which, in the first case, are often absent, and in the second are often par- tially dissolved. This last violet liquid has been regarded by Ehrenberg® 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. ts 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- derg,® 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, 326, 329. Ehrenberg has, rooreover, in T'rachelius melea- p. 75. gris, confounded the contractile cavities with those 2 Focke loc. cit.; also Erdl, Miller’s Arch. 1841 non-contructile, and which receive the food. p. 278. me p. 786; also Meyen, Muiller’s Arch. 1839, 2 Abhandl. d. Berliner Akad. 1833, p. 179 5 also “ Die Infusionsthierchen,” pp. 319, 338, 339.* 1 Vaginicola and Vorticella. See Focke, Isis, Diatomacez, 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 tnese heterogeneous particles, and, on the whole, present characteristics as remarkable az 8 Loe. cit. p. 262. 4 Muiler’s Archiv. 1839, p. 81. those of any animaleule with which we are ac quainted. — Ep. *[§ 13, note 2.) In this connection should be noticed the experiments of Will (Miiller’s Arch. 1848, p. 509). He found evidences of a biliary ap- paratus, with Vorticella, Epistylis, and Bursaria. These evidences are based on chemical re&ction, 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 VI. AND VII. 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- Junar ciliated lobe. 8 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-lilye teeth are arranged in a cylinder so as to resemble a weir. 6 The cesophagus is short in Oxytricha, Sty- lonychia, and Eupjotes ; but is elongated or spi- ral in Vorticella, Carchesium and Epistylis ; *[§ 15, note 1.] Kélliker ( 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 dof ab sub- while it is long and arcuate in Bursaria trunca- tella and cordzformis. 6 The undigested matters accumulate about the anus, and when this opens are expelled from the parenchyma with a certain force. With Nassula elegans, the greater or Jess portions of the Oscil- latoria gracillima (K#utzing) 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 di ion, gradually 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 Nassufa 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 ita interior. — Ep. 30 $ 1T. These movements succeed each other at more or 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 jirst attempt at a circulation of nutritive fluids. From an optical illusion similar to the one mentioned as belonging to the vacuole ($ 13) the liquid of these pulsating cavities has a reddish hue. INFUSORIA AND RHIZOPODA. § 17. A round, pulsating cavity is found in the genera Vorticella, Epistylis, Loxodes, and in the following species: — Ameba diffluens, Paramecium kolpoda, Stylonychia mytilus, Euplotes patella, §&-c. With Actinophrys, Bursaria, Trichodina, there are from one to two; with Arcella vulgaris, three to four ; with Nassula elegans, there are four placed in a longitudinal line on the dorsal surface. With Trachelius 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 Trachelius 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. 321, Taf. XXXIII. fig. viii.), deceived by this illusion, has taken the eight totwelve 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. 168.) 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. 355). A ding to him, the | vesicles, upon con- traction, pour the sperm upon the eggs contained in the body. It really seems very strange that * these animals should practise uninterruptedly these pollutions throughout their entire life. These ani- mals have neither testicles nor ovaries, and the function of these cavities is not, therefore, that ‘assigned to them by Ehrenberg, —but is, as L think, with Wiegmann (Arch. f. Naturg. 1835, I. p. 12), analogous to that of a heart. 1 Dujardin, ‘Ann. d. 8c. Nat. Zool. tome X. PL. XY. fig. 35 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. § 18. 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 Actinophrys 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 ahead 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 caleareous, 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. II. fig. xvii. 1 Bhrenberg (Ibid. p. 303, Taf. XXXI. fig. v1.1) appears to have taken the protrusion of these cou tractile vesicles for that of a snout. INFUSORIA AND RHIZOPODA. $$ 20, 21, 22. 32 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. s § 21, Nearly all the Infusoria and Rhizopdda 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 isabout 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 (Vestcule seminales of Ehrenberg). § 22. 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. 1That 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, Lorodes, and Bursaria. 4 Bursaria, Opalina, Glaucoma, Chilodon, Pa- ramacium, 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 taker this nucleus for a seminal gland. (Abbandl. d, Berliner Akad. 1835, p. 163. Also, loc. cit.) $ 23. INFUSORIA AND RHIZOPODA. as It is not rare that a variable number of these round nuclei, arranged 1 in a row, traverse the body in a tortuous manner. This is so in Stentor coeruleus and polymorphus, in Spirostomum ambiguum, and in Trachelius moniliger. In many instances the nucleus has the form of an elongated band, which is slightly curved in Vorticella convalluria, Epistylis leucoa, Prarodan 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 Lozodes bursuaria, 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 enicaltlats, the nucleolus has a similar dot, and thus the nucleus as a whole resembles a cell. § 232. |: 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 long time, or even inereases 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. That the nucleus contained in Infusoria plays an 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. 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. Wirutw 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. 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 Midler, their position in this department has long been established. Muiller’s researches have been mostly on the Hchinoderms, 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. 385 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 Hydroid Polypi, as though they were referred to the Mollusca and Acal- ephae, where truly they respectively belong. Horror. BOOK SECOND. POLYPI. CLASSIFICATION. § 24, Tue Poxyer 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: Gor@onrna. Genus: Gorgonia. Famity: Isrpga. Genera: Corallium, Isis. Famity: Tusrporina. Genus: Tudipora. Famity: ALcyonrna. Genera: Alcyonium, Lobularia, Alcyonidium. Famity: Pernnatoina. Genera: Veretillum, Pennatula, Vir gularia. § 24, THE POLYPI. 37 Famity: SErruLaRIna. Genera: Sertularia, Campanularia. Famity: ZoanTaina. Genus: Zoanthus. Famity: Hypgina. Genera: Hydra, Eleutheria, Synhydra, Coryne, Syncoryne, Corymorpha. Famity: Actrnina. Genera: Actinia, Eumenides, Edwardsia. ORDER II. BRYOZOA. The digestive canal is closed from the general cavity of the body, and opens behind through an anus. Famity: REereporina. Genera: Eschara, Cellepora, Flustra, Bicellaria, Retepora, Telegraphina, Tendra. Famity: ALCYONELLINA. Genera: Cristatella, Alcyonella, Bowerbankia, Vesicularia, Lagenella, Plumatella, Lop Bg BIBLIOGRAPHY. Ellis. Essai sur )’Histoire naturelle des Corallines et d’autres produc- tions marines du méme genre. La Haye, 1756. Pallas. Hlenchus zoophytorum. Hagae 1766. Cavolini. 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. 18382. 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 l’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 _ my notes, and especially those of Aliman. D. 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 he 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 azial, 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 df 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, Anon. d. Sc. Nat., Zool. IV. 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. *It 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 4g generally an internal skeleton, as. for instance, p. 403, Taf. I.-III.) has described and figured these. spicula under the names of Spongolitkis and. Lithostylidium. 5 The Madreporina. 6 Millepora, Madrepora, Oculina and Astraeae ? 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, ’50, 51. — Ep. $$ 27, 28. THE POLYPI. 39 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 Nats, 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 given by Owen (Trans. of the Zool. Soc. I. p. 325, Pl. XL fig. 18, or Cyclop. Anat. and Phys. II. p. 130, fig. 78), and Diesing (Ann. d. Wiener Mus. I. Abth. 1, p. 18, Taf. L. I1.).t He says: ‘I believe the nervous system described by Blanchard to be bands of muscular fibres which cross each other between the fossae of the probos- cis : at least, this is so in the new species of Taenia from Amia calva which was observed alive for sevy- eral hours; and I could discover no nervous threads, but only muscular fibres, which had ex- actly the srrangement of Blanchard’s nervous sys- tem.” See, however, Valenciennes’ report to the Acad. des Sc. in the Comp. Rend. 1847, XXIV. p. 1034, also Blanchard’s response to Dujardin, Ibid. 1849, XXIX. p. 60.— Ep. t [§ 104, note 3.} Blanchard has found with Linguatula ano*her ganglion above the cesopha- 110 THE HELMINTHES. § 104. ‘The central nervous system of the Acanthocephali is very distinct. It is always concealed at the bottom of the sheath of the proboscis, which this last, being never in a state of complete retraction. does not fill. Tt consists of a dense mass of ganglionic, cellular globules blended together, and here and there may be seen through the cell-membranes their nuclei and corpus- cles. This comparatively large mass sends off nerves in every direction, but the tenuity of these prevents their being traced, especially after they have entered the muscular walls of the proboscideal sheath. With the Gordiacei,™ and Nematodes, a nervous system has been found with certainty only in Strongylus gigas. Here a cord arises from a swell- ing in the head, traverses the whole length of the body upon the median ventral line, and terminates at the posterior end of the body in another swelling. nervous system of the Sipunculidae. 4 Ihave thus found the nervous system of the , Acanthocephali in Echinorhyncus gigas, angus- tatus, haeruca, and proteus. It can be easily ob- served by carefully pressing or tearing the probos- cideal sheath. In thus tearing, you sometimes completely expose the ganglionic mass with the roots of the nerves. In no species that I have dis- sected have I been able to find the ganglionic ring mentioned by Henle (Froriep’s neue Not. No. 285, p. 330, and Miiller’s Arch. 1840, p. 318) as found about the genital orifice of Echinorhyncus nodulosus. Dujardin also (Hist. Nat. d. Helm. p. 495, 491, Pl. VI. fig. D. 4), has not observed it, but he dis- tinctly perceived the central mass at the base of the proboscis, and has figured and named it as un corps glanduleux ou ganglionaire. - 5 As yet no nervous system has been found in the Gordiacei. Berthold (Uber den Bau des Gor- dius aquaticus, 1842, p. 12) has been inclined to regard as nerves two delicate filaments which traverse the cavity of the body of Gordius ; but, as these give off no lateral branches, this opinion - cannot be admitted.* 6 Many Helminthologists have err ly taken for nerves the delicate projecting lines which, situ- gus, which he regards as a brain; these observa- tions have since been confirmed by Van Beneden (Ann. d. Sc. Nat. XI. 1849, p. 319), who, however, regards this mass as belonging to the sympathetic system. But, however viewed, an cesophageal col- lar has been distinctly made out, thus confirming the views of Cuvier. In regard to the splanchnic system of nerves with these animals, Van Beneden (loc. cit.) de- scribes it as consisting of two ganglia lying on the cesophagus back of the wsophageal collar, and from which pass off two filaments, which run along the cesophagus, and enter the collar laterally. He thinks the two ganglia are united by a transverse It sends off in its course lateral filaments, thus resembling the ated directly subcut and often blended with the skin, traverse the whole length of the body of many Nematodes, and have been called the ventral and dorsal lines. Their lateral branches, as already observed, are only transverse muscular bands. Quite different from these is the longitudinal cord, which Otto (Magaz. d. Gesellch. naturf. Freunde au Berlin, 7th Jahrg. 1816, p. 225, Taf. V.) has described and figured as belonging to the nervous system ; a view which I am disposed to adopt, in spite of Nitzsch (Ersch and Gruber’s Encyclop. VI. 1821, p. 45) and other Helminthologists. In a large female Strongylus gigas, now under my eyes, there is a simple longitudinal cord beneath the muscular envelope, and therefore in direct con- nection with the skin, and which extends along the ventral surface. In its course it sends off less lateral branches, which in their inti- mate structure are quite different from the trans- verse muscular bands. But neither here nor upon the nerves of other worms have I ever seen the enlargements spoken of by Otto. Grant’s figure of a double nervous filament traversing the body of Ascaris is probably imaginary 3 see Outlines of Comp. Anat. p. 186, fig. 82, A. commissure. Further behind is another and larger ganglion on each side, and from which pass off filaments to the digestive cavity. See also my note under § 99. — Ep. ’ * [ § 104, note 5.] This view of Berthold is sup- ported also by Blanchard (Ann. d. Sc. Nat. 1849, XII. p. 6), who affirms that he has observed on both sides of the body a double longitudinal cord, which is usually very. distinct. This, examined microscopically, appeared to be composed like the nerves of the other Helminthes. Blanchard, how- ever, did not succeed in tracing these cords to any cephalic centres. Nothing of special value, there= fore, is known on this subject. — Ep. $$ 105, 106. THE HELMINTHES. 111 CHAPTER IV. ORGANS OF SENSE. § 105. The sense of touch is probably the only one well developed with the Hel- minthes. The granulations, warts, papillae, filaments, and retractile lobes, found upon the head of some species,” are, without doubt, the organs of this function. The red and black points upon the back of many, both adults and larvae, and which have been regarded by some naturalists as organs of vision, appear to be only pigmentary spots; for they contain nothing like a light-refracting body. CHAPTER V. DIGESTIVE APPARATUS. § 106. The digestive organs with the Helminthes have a variable degree of development in the different orders. In the Cystici, Cestodes, and Acanthocephali, neither mouth nor alimentary canal is perceived. In the first two orders, there is, however, a system of vessels which may be regarded as a digestive apparatus; but these are designed for circulation, rather than for digestion, since their walls are com- plete throughout and have no openings, as has erroneously been supposed, which communicate with the suckers of the head; and their contained nutri- tive material is received by them through the skin in an endosmotic manner.” 1 These tactile granulations are found with many species of Ascaris, as, for instance, in Ascaris osculata, between the large oral collars ; in Physa- optera alata, they surround the oral extremity of the body as a single row ; but they form a double one in Ascaris trunculata. With Distomum daureatum, and nodulosum, they are found upon the borders of the oral sucker. With Holostomum exrcavatum, and podomorphum, there are two re- tractile lobules protruding from the sides of the mouth; and in Holostomum alatum, these have antenna-like filaments ; see Nitzsch’s figures of Holostomum, in Ersch and Gruber’s Encyclop. IIL. p. 399, IX. : 2 These dark pigment-dots upon the infusori- form embryos of many Trematodes when they es- cape from the egg, and of which there is only one upon the neck of Distomum nodulosum, and hians, and two upon Monostomum mutabile, have been taken for eyes by Nordmann (Microgr. Beitr. Hft. 2; p. 189), and formerly by myself also (Wiex- mann’s h. 1835, I. p. 69, Taf. I. fig. 3, 4, 5). Three of these dots have been observed upon a darva of a Monostomum which Nitzsch (Beitr. zur. Infusorienkunde, p. 29, Taf. I.) has deseribed in Cercaria ephemera; I have seen only two upon the back of many cercarian larve. Of this same nature are the two red dots of Scolex poly- morphus (Muller, Zool. Danica. Tab. LVITI. fig. 16, 17), as also the brown ones upon the neck of Gyrodactylus auriculatus (Nordmann Microgr. Beitr. Hft. I. p. 108, Taf. X. fig. 4). Finally may be mentioned Amphistomum subclavatum, which has two large oval black dots upon its neck. These pigment-cells are physiologically, without doubt, simply colored spots, which in Polystomum inte- gerrimum are highly developed, forming a widely- spread subcutaneous net-work. Sometimes, and especially in the various Cercariae, and in many in- dividuals of Amphi. subcl , these dots have a very effaced aspect; this is probably due to a dissolution of the walls of the cells, — the pigment-granules being then scattered through the Bkin. 1It bas already been observed that the four suckers of Taenia, regarded by Nitzsch as oral orifices, are imperforate at their bottom. Owen (Cyclop. Anat. &c. II. p. 181) has fallen intea THE HELMINTHES. $ 107. 112 The food enters the cavity of the body of Echinorhyncus probably in the- same manner, for their skin has great power of absorption. The Acanthocephali have this peculiarity, that between the skin and the: muscular walls of the cavity of the body there is a thin layer of finely-. granulated parenchyma, often of an orange or yellow color, which is traversed by longitudinal and transverse canals. ; These canals, having no proper walls, form a continued vascular system,. and contain a liquid filled with granules and vesicles. As this system is. completely closed, and cannot therefore receive nutritive substances from without, it must be regarded as nutritive or circulatory, and not digestive,. as it has been by many naturalists. § 107. In the other groups of the Helminthes the digestive organs are pretty: generally well developed. : The Trematodes have a mouth situated usually upon the border of the. cephalic extremity, and where there is asucker occupying its bottom. From this there passes along the middle line of the neck a thin-walled cesophagus,. which is often of an S-like form. Directly behind the mouth or oral sucker, but sometimes a short distance removed from it, the oesophagus is surrounded by around or oval muscular pharynx.” From the extremity of this pass off, usually, two blind intestinal tubes, which, passing along both sides of the body, extend generally to its posterior extremity.” The other forms of the digestive canal are as follows: in Monostomum mutabile,” and fla- vum, the two intestinal tubes, instead of ending coecally, form the are of a circle; in Aspidogaster, a simple and uniform intestine succeeds upon the pharynx, and ends in a coecum at the posterior extremity of the body ;® in Gasterostomum fimbriatum, this canal is very short, and terminates in. the same way, but there is a mouth in the middle of the ventral surface; in Bucephalus polymorphus,® the structure is similar; and in Pentastomum, similar error in regarding these organs as mouths, not only in Taenia and Cysticercus, but also in Bothriocephalus. I have been unable to find a mouth upon the cephalic extremity of the Cestodes, as has Mehlis (Isis, 1831, p. 131), or upon that of Taenia solium, as has Owen (Lect. on the Comp, Anat. &c. p. 48, fig. 21, a.). The fossa sometimes found upon this last, is due to the retraction of the circle of hooks, or of the proboscis, within the sheath, : . 2 Most Helminthologists admit that Echinorhyn- chus receives its food through a small orifice at the extremity of the proboscis, the sheath of the last aiding in suction and deglutition. I have been unable to convince myself of the existence of this orifice, and never have found food in the cavity of the sheath. On the other hand, I have often, like Creplin and Mehlis, seen Echinorhynchus re- ceive and reject liquids through the skin, 1 With Distomum globiporum, the pharynx is somewhat removed from the oral sucker ; see Bur- meister, in Wiegmann’s Arch. 1835, IL. fig. Taf. 1, 3. In Distomum echinatum, militare and allied species, the cesophagus is usually very long. ‘But in Distomum oxycephalum, it is very short; and in Distomum appendiculatum, it is entirely wanting, and consequently the intestinal bifurcation is directly behind the pharynx. 2In Mon Amphist Hy, lost mum, Distomum, and Polystomum, the intestinal bifurcation extends to the posterior* extremity of the body. With Distomum chilostomum, and many other species of this genus living in the Neu roptera, the whole intestine is reduced to two short right and left coeca, which are given off from the end of the cesophagus. $ 3 Creplin, Nov. Observ. de Entozois, fig. 10, 11. 4This arrangement has been also, but errone ously, assigned to Distomum tereticolle ; see Wagner, Lehrbuch der vergleichenden Anat. 1834,. p. 75, and Creplin, in Ersch and Gruber’s Ency clop. XXIX. 1837, p. 314. This error is probably due to the inaccurate copy- ing of figures; see Ann. d. Sc. Nat. If. 1824, p. 493, Pl. XXIII. fig. 4, 5; and Schmalz, Tabulae Anat. Entozoorum, Tab. VIII. fig. 2,3. By refer- ring to the original figure inthe Memoir of Jurine ate de la Soc. de Phys. et d’Hist. Nat. de enéve, IT. pt. 1, 1823, p. 149, fig. 4, 5), from which these have been copied, there is found no trace of a closed, arcuate intestinal canal behind. More- over, Jurine expressly says that he has seen the- i 1 tubes of Dist terreticolle, as coeca. 5 Baer, in Nov. Act. Acad. &c. XIII. pt. 1, p.- 536, Taf. XXVIII. ; also Diesing, Med. Jahrbuch. d.k. k. ésterreichischen Staates. XVI. 1834, p. 423,. fg. 8-11. ? ? Bucephalus polymorphus is probably a larval $ 108. THE HELMINTHES. 118 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 esophagus, which is usually dilated claviform at its lower extremity. When the cesophagus is very long, it has one or more constrictions. of three longitudinal muscles which are united by longitudinal seams. It is nearly always composed 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 Lucioperca. 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 sp allied to Mon trigo 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. ITI. fig. 3. These lateral caeca are more or less ramified in Oc- tobothrium palmatum, sagittatum, Merlangi, Polystomunt appendiculatum, and Tristomum elongatum (Leuckart, Zool. Bruchstiicke, Hft. 3, p. 26, 64, Taf. I. fig. 4, c. b. Taf. U1. fig. 5, d. 5 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 Mehdis, 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. Tift. 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-Wwork already mentioned. 9 The digestive canal of Trematudes 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 10* 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. 1848, II. 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 Mehiis, Isis. 1831, p. 78, Taf. II. 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 svlid, horny pieces. 3 With Anguillula fluviatilis, Oxyuris vermi- cularis, Ascaris inata, 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- slve at short intervals ; see Mayer, Beitr. &c. Taf. I. Ul. 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 beem 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 esophagus. § 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 cesophagus to the beginning of the intestine. ® 4 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 «esophagus, was first observed by Mehlis (Isis. 1831, p. 91, Taf. IL. 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- $a, 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, IL. p. 322. 2 Mehlis (Isis, 1831, p. 81, Taf. II. fig. 6) has observed with Strongylus armatus, an annular vessel surrounding the mouth, which communi- * [ § 108, note 6.] See, for the alimentary canal 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. 134). 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. IL. Abth. 2, p. 224, 226, 228, Taf. XVII. fig. 8, 9, Taf. XVIIL. fig. 3). Iam 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. 3809) ; such are, Ascaris mucronata, angulata, oscu- lata, spiculigera, aucta, acus, and labiata. It is remarkable that with the exception 0 the last two, all these have also a caecum upon the intestine. 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- appendiculatum, there is this 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 jong, cap , 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 demmnisci, 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- cchyma of the proboscis. n many, the lemnisci are surrounded by muscular fibres, which, con- verging to the posterior uxtremity 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- aminthologists for a digestive canal, has been fig- ured by Westrumb (De Helminth Acanthocephalis Tab. II. 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 subcutaneous parenchyma is swollen, and the skin is raised here and there into vesicles. 2 With Echinorhynchus angustatus, acus, Susiformis, proteus, and polymorphus, the two femnisci have a riband-like form. In Echino- wrhynchus 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. 83 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, voluminoua, transparent and apparently vesicular bodies ; see Westrumb loc. cit. Tab. II. fig. 7. Similar bodies in the lemnisci and subcutaneous parenchyma, are found with Echinorhynch laviceps ; see Mil- ler, Zool. Danica. Tab. LXI. fig. 3. These bodies are, moreover, 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 piscium, 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. duces the circulation. Its canals have proper walls, the contraction of which pro- 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 I have been 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, nouy, Eait. Zoophytes, Pl. XXXYV. fig. 2.— Ep. Platner (Miller’s Arch. 1838, p. 572, Taf. XIIL..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 Taenia 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- riocephtius 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 Diplosti Word Microgr. Beitr. Uft.1, Taf. Tl. 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. Laurer also (de Amphis- tomo conico. p. 10, fig. 22), has not carefully dis- tinguished them 5 and Nordmann 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 ag + [§ 110, note 6.] Berthold (Ueber den Baw des Wasserkalbes. &c. loc. cit.) has described a vascular system with the Gordiacei; but Blanchard (Ann. d. Sc. Nat. 1849, XI. p. 7) has failed to- confirm his statements after very careful research. — Eb. $ 112. THE HELMINTHES. 117 CHAPTER VII. RESPIRATORY SYSTEM. § 112. A respiratory system has not yet been found with certainty in the Helminthes, i 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 Hchinoderms, 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 Muller’s Arch. 1846, p. 2, Taf. I. fig. 2.* 1 Bojanus (Isis, 1821, p. 187, Taf. ITI. fig. 51- 5) 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. 2T have quite distinctly seen these vessels with Diplozoon paradozum, Aspidogaster conchi- cola, Distomwm 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: 23) has recentiy 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 Nordmann 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 pletely closed trach apparatus (see below), admitting no air from with- out. the Cestodes and Trematodes, but see the | piates of Blanchard, Ann. d. Sc. Nat. 1848, X. Pl. XI. — Ep. with > 118 THE HELMINTHES. § ITS. CHAPTER VIII. ORGANS OF SECRETION. § 118. No orga 1s 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 Nardo (Heusin- ger’s Zeitsch. fiir organische Phys. 1827, I. 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 jfimbriatum, 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. 3 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 twocanals 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 Taeniae, and it may be asked if they are not an effete mate- rial, which, not being contained in proper organs, is with these H thus sub ly deposited. 8 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 Testudo 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 fisswration 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.” Gremmation 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 Cercaria, 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. § 1165. Tn 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 J'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 Taenia solium, cucumerina, and others, move freely, and are vo individualized, that they resemble some Trematodes. 2See Chemnitz, De Hydatibus Echinococci hominis commentatio, 1834 ; Muller, in his Arch. 1836, p. CVII. ; and Siebold, in Burdach’s Phys- iol. II. 1837, p. 183. 1 According to Nordmann (Microgr. Beitr. Hft. 2, p. 141), Diesing (Ann. d. Wiener Mus. I. Abth. 1, p. 9), and Miram (Nov. Act. Acad. XVII. pt. 2, p. 636), the male and female genital organs of the genus Pentastomum, classed by 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, 1835, I. p 325). The only way to settle this point is by analyzing accurately the contents of these organs ; a method pursued by Valentin (Repertorium II 1837, p. 185), 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 a simple 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 ® yeservoir, 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 egg-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 retinite 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. 1826, I. p. 217, Taf. VI., and in Miller’s Arch. 1836, p. 232, Taf. X. fig. 1. 3 The ovary here is always smaller than the testicle, and sometimes as to form very closely resembles it, as in Distomum globiporum, and dongicolle, mihi (from the urinary bladder of Cottus gobio); consequently it may easily be ‘taken for a third testicle. 4 With Monoastomum, it lies wholly at the pos- terior extremity. 5 In Polystomum, Octobothrium and Diplo- oon, the germs are so large that they may easily de taken for perfect eggs. There is here, moreover, between the cell-wall zand 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 thas 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 organs 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 ; 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 ag vitellus-secreting organs, are almost invis- ible. 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 enCogenous 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. 121 _ The neck of the internal seminal vesicle (Vesicula seminalis interior), ‘lischarges its contents at thissame place into the uterus, through a special Vas deferens from one of the testicles. The Uterus commences as a narrow tube, which may be regarded as a Tuba Fallopii. 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 Vesicula seminalis exterior. From each testicle there passes off, also, a third Vas deferens which opéns into the neck of the Vesicula 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 into a tubular penis.“ There is on¢ 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- é ity. 18) 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. don nhiet, perceived unless they are quite isolated. When put in water they become twisted together, and assume a loop-like arr — their i instantly ceasing. For the development of the spermatic particles of the Trematodes, see Kélliker, Die Bildung du 98 Ihave found one testicle only, in mum subclavatum, and Aspidogaster conchicola, although I have seen three or four in Distomum appendiculatum, and cygnoides. With Di. tum, the two 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, woxyurum, echinatum, globiporum, and Amphis- icum, icles have many depres- ‘sions 3 see Bojanus, Isis, 1821, Taf. IL. fig. 25-27 ; Burmeister and Siebold, in Wiegmann's Arch. 1835, IL. 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. II. fig. 14-17, and Diesing Ann. d. Wiener Mus. I. Abth. 2, Taf. XXII. 12 In the of the Tr , the devel- opment of the spermatic particles occurs after the usual mode. The bundles 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 tod *[§ 115, note 12.] Thaer (Muller's Arch. 1850, Pp. 602, Taf. XXI. fig. 19) has described and fig- 11 8 faden in Blaschen, loc. cit. p. 44, fig. 31.* 18 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 Di. lima, le ; variegatum, and ovatum ; but it is especially so with Aspidogast hicola, and M 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 infront of the ventral sucker. With Distomum clavigerum, and ovatum, it is upon the sides of the neck, and with Distomum dale, and hol e bly, it is on :] ured the spermatic particles of Polystomum ap- pendiculatum as Cercaria-form. — Ep. 122 § 115. THE HELMINTIES. In the terminal, constricted portion of the uterus, eggs, vitelline cells, and spermatic particles are often found mixed together. It is probably here that the egos 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.“ Tn 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 Liguda, 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 around 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. 3, 6) has seen ten similar ribs with Octobothrium lanceolatum. Thave 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 receiving their usual contents. With Amphistomum subclavatum, Octobothrium lan- ceolatum, Polystomum integerrimum, and ocel- datum, and Diplozoon paradorum, 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 eggs 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. 24, Taf. II. 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, Muller’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 5 see Dujardin, Hist. Nat. d. Helminth. Pl. VIII. fig. G, B. 3.* 20 With Caryophyllaeus mutabilis, there is only a single cirrhus-sac upon the ventral surtace of the posterior body, and from which a delicate long penis often protrudes. 211 think I have seen an ovary in each of the segments of Bothriocephalus punctatus, and T'ae- nia ocellata. As such, ought, perhaps, to be re- garded those organs which Eschricht (Nov. Act. Acad. Leop. 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 Taenia ocellata, 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 3 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. Their simple, oval, brownish-yellow envelope, has also, sometimes, an operculum. 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 Taenia ocellata, and its arbo- rescent divisions with Taenia solium, are very easily seen; see Delle Chiaje, Compendio di Elmintografia umana, Tav. ILI. fig. 10. 2% The cirrhas-sac is either short and pyriform, or very long. With very many T'aeniae, as with Taenia amphitrica, lanceolata, multistriata, scolecina, and setigera, the penis has numerous small spines pointing backwards; see Dujardin, Ilist. d. Helm. Pl. IX.-XI. That of T'aenia infundibuliformis is surrounded with very large bristles ; and according to Dujardin (loc. cit. Pl. IX. B. 210) this is also true with Taenia sinuosa. 25 By very slight pressure, the spermatic parti- oles contained in the Vesicula seminatlis of the cirrhus-sac are pressed out through the penis ; this is so with Bothriocephalus punctatus, latus, Taenia cucumerina, planiceps (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.* 2% With Ligula, Bothriocephalus nodosus, latus, claviceps, ditremus, punctatus, and te- gilis, proboscideus, rugosus, and with most Tae- niae, the cirrhus-sac and the vagina open by a common genital orifice upon the lateral border, and usually through a papilla. With Taenia cucumerina, and bifaria, mihi-(from the intestine ot Anas leucophthaimus), I have found an orifice of this kind upon the two lateral borders of each segment, and behind which were the genital or- gans.t 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 Kélliker (Muller’s Arch. 1848, 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- tformis, proboscideus, Taenia porosa, lanceo- trapterus, the two genital op gS are ted 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 Triaeno- 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 Taenia. 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 lata, llata, setigera, and solium. With Tae- 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 Taenia 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 ot Taenia. The round and doubly-enveloped eggs years, by Blanchard (Ann. d. Sc. Nat. X. 1848, p. 821) 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 vecupy 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 fively-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 Ligamentum 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- lopit. 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- eles, one before the other, and attached to the Ligamentum suspensorwum. of Taenia cucumerina’ (Creplin, Observ. de Entozois fig. 12, 13) 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. Herethe 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. yp. 67), who has observed the eggs of the Cestodes 2 The long eggs of many Exhinorhynchi 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 otliers, 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 gee (Hist. d. Helm. p. 495, Pl. VII. fig. composed like those other animals,— with a germin- ative vesicle, &.—Ep. |; $117. THE HELMINTHES. 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 (Vesicula 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 Vusa deferentza. 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 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 ejaculatortus. 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. IL. fig. 245; and Nitzsch, in Ersch and Gruber’s Encyclop. VII. 1821, plate for the Acanthocephala, fig. 2, 3, i. With Echinorhynchus claviceps, I have found only one of these bodies. 6The copulatory organ, which protruded has mostly an oblique direction, has been very exactly figured by Dujardin (Hist. d. Helm. p. 493, Pl. VII. fig. D, 1, D, 2). 7 For the spermatic particles of the Acanthoce- phali, see my observations in Muller's Arch. 1836, p. 232. 8 This waxy sub incrusts sc 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. Ld . "1 For the simple genital tube with its various parts of the female of T'richocephalus dispar, see Mayer, Beitr. &c. Taf. Il. 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. 28), 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- faris, and striatus; or both pass side by side behind, as in Ascaris aucta, mystar, 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 inflexus has, posteriorly, numerous constrictions, giving it a moniliform aspect. animal nouy. édit. Zoophytes, Pl. XXXV. fig. 3v, 3c, 34, 8, 31). —Ep. 126 THE HELMINTHES. $ 117. 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 Vesicula 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 borders of the vulva appear quite swollen, With lias been described by Szebold (Burdach’s Phys- inl. loc. cit. p. 208), by Bagge (Dissert. de. Stron- gylo, &c., fig. 1-5), and Kélliker (Muller's Arch. 43, 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 inflecus. ‘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 Miller’s Arch. 1835, p. 602, Taf. XIV. fig. 1L. In the mature eggs, which are nearly always oval, it israre that the double colorless envelope can be elearly 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 Muller’s Arch. 1843, Taf. VI. fig. 16-19.* 3 With Ascaris dactyluris, Cucullanus ele- gons,, Strongylus nodularis, and striatus, the * [§ I17, note 2.) Primitively, the ova of Asca- ras 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 Trichosoma, this swelling is so attached to the vulva as to resemble a prolapsus of the vagina (Dujardin, Hist. d. Helm. Pl. I.). With Filaria attenuata, inflero-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 paradoxis, 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. Tl. fig. 8. As yet I have observed only a few exceptions to this typical form with male Nema- 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 Letdy, loc. cit. p. 43, Pl. VIL. 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 Filaria papiliosa are quite near the oral ori- fice. Ihave been unable to confirm this observa- tion, at least with Fidaria attenuata, inflexo-cau- data, and another species found in the thoracic cavity of Sturnus vulgaris. 7 With T'richocephaius, 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. L., and Dujardin, Hist. d. Helm. Pl. L-I0. With nearly all the other Nematodes the penis is double. it is very long with Ascaris acuminata, brevi- caudata, depressa, spiculigera, and Strongylus paradovus ; but is very short with Ascaris ensi- caudata, semiteres, Cucullanus elegans, Fila- ria attenuata, inflezo-caudata, Spiroptera an- thuris, and Strongylus inflexus. 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 N , the penises are sul ‘5 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, vestcularis, and spicu- digera, 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 pani ted *[§ 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 from its histological relati 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 ). — Ep. . 140 THE TURBELLABRIA. their chorion contains only loosely-arranged vitelline cells, among which there is seen no trace of one or more germinative vesicles. The vitelline cells always contain, beside a finely-granular albuminous substance, a round , nucleus which has a nucleolus. Both the nucleus and the granular sub- stance are shifted from one side to the other of the cell by the very re- markable peristaltic movements of the cell-membrane. After a time, these movements cease, the cell-membrane disappears, and the contents mix with those of other cells which have been affected in the same way: by these means, little collections of vitelline substance here and there are formed, which increase by the addition of other cells, — and finally are transformed into roundish, nicely-defined embryos which become covered with ciliated epithelium. From this time the embryos do not increase as before by the external fusion of cells, but there is a muscular, discoid oesophagus formed upon their periphery, and through this the remaining cells are ingested and $ 129. assimilated within the animal. Still later, the embryo, hitherto spherical, becomes flat and elongated at two opposite points ;— ultimately, and upon the appearance of the eye- specks, it assumes exactly the form of the adult Planariae. The size of the young Planariae depends upon the number of embryos developed in the Same egg, for the smaller this number, the larger the embryos at the time of their hatching, and vice versa. The cause regulating the number of embryos in an egg is yet un- known.* © 1 See my details upon this subject in the Bericht. ueber die Verhandl. d. Berl. Akad. 1841, p. 83. During the development of Planaria, one can, after a while, ascertain the number of vitelline cells assimilated by fusion and deglutition, by counting their nuclei which are easily seen in the parenchy- ma of the body. According to Focke (loc. cit. p. 201), the eye-specks, and the cesophagus are de~ veloped very early in the young Mesostomum Ehrenbergii ;— a species with which each egg contains a single embryo only, and which is devel- oped while the egg is in the uterus. * [End of §129.] Recent embryological studies have thrown some light upon this point —the alleged plurality of embryos in a single egg. The so-called egg in these cases is almost undoubtedly an ovarian sac, in which are developed many germs; some of these germs may perish, and the fewness of those remaining would give the appearance of an egg with many germs. — Ep. + [§ 129, note 1.] The development of Plana- ria has been also observed by Schmidt. Die Rhab- The remarkable movements of the vitelline cells in the eggs of the Planariae, and which I was the first to observe, have since been confirmed by Kél- liker, with Planaria lactea; see Wiegmann’s Arch. 1846, I. p. 291, Taf. X. Iam unable to say whether or not the spontaneous movements observed by Quatrefages (loc. cit. p. 169, Pl. VIL. fig. 6-9) upon the larger portions of the vitellus of Polycelis pallidus while in the oviducts, are of the same na- ture ; this naturalist himself supposes that these portions were the embryos of this Planaria.t doc. Strudelwiirmer, &c., p.17; by Agassiz (Proc. Amer. Assoc. Advancem. of Sc. 29d meeting, 1849, p. 438), who made the interesting observation that the Infusoria-genera, Ko/poda and Paramaecium, are only larve of Planaria; by Girard (Ibid. p. 398), and by Miller (Muller’s Arch. 1850, p. 485). Muller has here some interesting remarks on the relations of the study of these forms to the class Infusoria. — Ep. $ 180. THE ROTATORIA. 141 BOOK SEVENTH. ROTATORIA. CLASSIFICATION. § 130. Tur body of the Roratorta is covered with a smooth, hard epidermis, and, from transverse incisions, at least at its posterior portion, usually ap- pears articulated ; while its anterior portion has vibratory retractile parts — the so-called rotatory organs. The very indistinct nervous system is almost wholly comprised ina cervical ganglionic mass. The fully-developed digest- ive canal lies in the large cavity of the body, and its anterior portion is provided with masticatory organs, while posteriorly, it terminates in an anus, Female genital organs alone have as yet been found with certainty. No one would deny that the Rotatoria, whose organization is so high, ought to be separated from the Infusoria, whose structure is scarcely advanced above that of a simple cell-nature. One can be in doubt only as to their other and proper place in the animal kingdom ; — whether, with Burmeister, they are to be placed among the Crustacea ; or with Wiegmann, Wagner, Milne Edwards, Berthold, and others, among the Worms. But the choice here between these two classes will not be difficult, for, as will soon be shown, they differ widely from the Crustacea. Aside from the absence of a ven- tral cord and of striated muscular fibres, these animals have vibratile or- gans upon the surface of their body, as well as upon their respiratory and digestive organs —a structure not found with the Crustacea, nor with the Arthropoda in general. Their development is non-metamorphotic, and they do not have articulated feet when they escape from the egg; while the Crustacea, and even those which, from a retrograde metamorphosis, be- come vermiform, have at least three pairs of articulated legs when hatched. On the other hand, they have, in common with most worms, an articulated body, internal and external vibratile organs, absence of a ventral cord, and, with all, the want of articulated feet. Although the uniformity of their organization does not admit of these animals being divided into orders, they can at least be considered as a sep- arate class in the great section of Worms. 142 . THE ROTATORIA. $ 181, Famity: Monorrocwa. Genera: Ptygura, Ichthydium, Chaetonotus, Ocecistes, Conochilus. Famity: Scurzorroca. Genera: Megalotrocha, Tubicolaria, Stephanoceros, Lacinularia, Melicerta, Floscularia. Famity: Potytrocpa. Genera: Enteroplea, Pleurotrocha, Hydatina, Notommata, Synchaeta, Polyarthra, Diglena, Triarthra, Eosphora, Cycloglena, Theorus, Masti- gocerca, Euchlanis, Salpina, Stephanops, Squamella. Famity: Zyeorrocwa, Genera: Rotifer, Actinurus, Philodina, Noteus, Anuraea, Brachionus. BIBLIOGRAPHY. See the works already cited under Infusoria. ADDITIONAL BIBLIOGRAPHY. Besides the writings of Brightwell, Hualey, Leydig, and others, quoted in my notes, see the following: O. Schmidt. Versuch einer Darstellung der Organisation der Rader- thiere, in' Wiegmann’s Arch. 1846. Frey. Ueber die Bedeckungen der wirbellosen Thiere. Gottingen, 1851. See also the new edition of Pritchard’s Infusoria, given under Book. first. — Ep. CHAPTER I. CUTANEOUS SYSTEM. § 181. Nearly all the Rotatoria are covered with a smooth,hard skin,® which is thrown into folds by the contractions of the subcutaneous parenchyma ; at the anterior extremity only, it is very delicate, and covered with vibra- tile organs, which also move to and fro with the parenchyma. With many, 1 With Chaetonotus, and Philodina aculeata, spines. With Noteus, and Anuraea, there are the structure of the skin is quite different from species whose faceted skin is roughened by innumer- this ; for its surface bristles with stiff points and able granulations. $$ 132, 133. THE ROTATORIA. 143 the annular sulcations of the skin, partial, or over its whole extent, give the body an articulated aspect.® Many others have a skin so hard and stiff as to be like a carapace. CHAPTER II. MUSCULAR SYSTEM AND LOCOMOTIVE ORGANS. § 132. The muscular system of the Rotatoria is quite distinct in many parts of the body. There can at once be observed, distinctly separated from the general parenchyma, unstriated muscles, of which some are transversely annular, and many others narrow and longitudinal. The first, subcuta- neous and widely separated from each other, are usually upon the borders of the segments of the body. The second, divisible into dorsal, ventral and lateral portions, arise from the internal surface of the skin, and are inserted at the cephalic or opposite extremity. The posterior extremity of those species which move freely, has two stiff points of variable length, which are moved as tentacles by two cylindrical, or clavate, caudal muscles. Some have long, movable bristles or pedicles, by which they row along or move by quick leaps. § 133. The prominent characteristic of the Rotatoria is the retractile, vibratile apparatus at their cephalic extremity, known as the rotatory organs. By these, they swim freely about, revolving upon their axis, or, when at rest, produce vortex-like motions of the water. The form, number, and arrange- ment of these organs varies much according to the genera, and may be used even to characterize families. The rotatory organ is either single, double, or multiple. Often it con- sists of a disc, supported by a pedicle of variable length, upon whose bor- ders are successive rows of regularly-arranged cilia, the motion of which gives the appearance of rotation to the disc itself. This apparent motion 2 With Conochilus, Megalotrocha, Lacinula- ria, Brachionus, Noteus, Squamelia, Notom- mata, and Stephanops, the tail is transversely marked or articulated. With many species of Hy- datina, Rotifer, Philodina, Actinurus, and Eos- phora, not only the caudal extremity, but the whole ‘body, is regularly segmented, and capable, espe- cially at the posterior extremity, of being intussus- cepted or drawn out, like a telescope. 3 A solid carapace, like the shell of Daphnia, is found with Brachionus, Anuraea, Noteus, Salpi- na and Euchlanis. 1 The muscles are smooth when at rest, but when contracted, they appear more or less distinctly pli- cated transversely. The assertion of Ehrenberg 4s therefore remarkable, that the longitudinal mus- cles of Euchianis triquetra are transversely stri- ated like those of the higher animals (Die Infus- ionsthierchen, p. 462, Taf. LVITI. fig. 8). 2 For the muscles of the Rotatoria in general, see Ehrenberg, loc. cit. and his description of the Hy- datina senta, in the Abhandl. d. Berl. Akad, 1830, p. 47. 83 Many Rotatoria use their caudal pincers as a fulcrum when creeping along. Philodina moves along in a leech-like manner, using its mouth and tail as suckers. Polyarthra has many bundles of bristles upon the sides of its body, which it uses as oars. Triarthra has under the throat and at the posterior extremiiy of the body, long stiff bristles, articulated with the body, and by which these ani- mals can leap like a flea. 144 THE ROTATORIA. $ 184. is quite remarkable with, those species whose single or double disc is not. crenulate, but entire.” With those whose organs are more numerous, but. smaller, this appearance is not observed. With Floscularia, and Stephanoceros, the rotatory organs have quite a different form. With the first, there are five or six buttdn-like processes. about the mouth, covered with very long bristles; these bristles produce usually but very feeble motions, and rarely give rise to vortexes. But Ste- phanoceros reminds one much of the Bryozoa, for its rotatory apparatus con- sists of five tentacle-like processes covered with vibratile cilia® The rota-- tory organs differ, moreover, from the ordinary vibratile cilia of epithelium, in being under the animal’s control, — that is, moved or kept at rest, at. will. CHAPTERS III. AND IV. NERVOUS SYSTEM AND ORGANS OF SENSE. § 134, Notwithstanding the transparency of the Rotatoria, and the distinctness with which their organs are separated from each other, yet their nervous. system has not yet been made out with certainty, for their bodies are so small that their peripheric nerves elude the microscope, and their principal nerves. and ganglia cannot be distinguished from the muscular fasciculi, the liga- ments, and the contractile parenchyma of the body. It appears certain, however, that in all, there is, as a nervous centre, a group of cervical ganglia, from which pass off threads in various direc- tions. 1 Conochilus, Philodina, and Actinurus. 2 Hydatina, Notommata, Synchaeta, and Dig+ lena. 8 See Ehrenberg, Die Infusionsthierchen, Taf. XLY. 4 According to Ehrenberg, there are, at the base of each cilium of the rotatory organs, many striated muscles, which, acting antagonistically, produce the motion (Abhandl. d. Berl. Akad. 1831, p. 34). . But neither Dujardin (Infusoires, loc. cit. p. 579), nor Rymer Jones (Compar. Anat. &c. p. 120), has been able to perceive this apparatus. The contractile parenchyma on which the virbra~- tile discs are situated, appears to be destined only for the protrusion and retraction of the rotatory organs.* 1 Ehrenberg, to whom we are indebted for our uliform body found upon most Rotatoria, and in- the neck of Hydatina senta, and Notommata col- laris (Abhandl. d. Berl. Akad. 1830, p. 52, Taf. VIII. 1833, p. 189, Taf. [X., and, Die Infusionsthier- chen, p. 386, &c.). Besides this ganglion, he has mentioned with Hydatina, Synchaeta, and Dig- Zena, many others scattered through the anterior part of the body, and connecting with the cerebral one by nervous filaments. Likewise, with Enter-- oplea, Hydatina, Notommata, and Diglena, he has regarded as a nervous loop, the two filaments which pass off from the cerebral ganglion, and go to the cervical respiratory orifice. Finally, he refers. to the sensitive system, a white sacculus, single'‘or double, and situated behind the cerebral ganglion, with Notommata, Digiena, and Theorus (Die Infusi chen, p. 425). Grant’s description of chief information upon the nervous system of these animals, first took for a cerebral ganglion the gland- * [§ 183, note 4.) Dobie (Ann. of Nat. Hist. 1848) speaks of two kinds of cilia with Floscularia ; “‘ one of the usual short vibratile kind, covering the inte- rior of the alimentary tube; the other extremely the nervous system of the Hydatina, as being composed of many ganglia and a ventral cord, Jong and filiform, of uniform thickness, and not. vibratile under ordinary circumstances.” They are: slowly moved, being spread out by the contractile substance of the lobes of the rotatory organ. — Ep. $$ 135, 136. THE ROTATORIA. 145 § 135. Beside the sense of touch, apparently located chiefly in the rotatory organs and their tentaculiform processes,” these animals have also an organ of vision. Usually this consists of a single or double eye-speck upon the neck; and sometimes, though rarely, of three or four red specks upon the forehead. These specks are usually very small, but nicely defined, and covered by a kind of cornea, They are situated immediately upon the cerebral ganglion, or are directly connected with it, by nervous filaments. CHAPTER V. DIGESTIVE APPARATUS. § 136. The digestive apparatus is well developed with the Rotatoria, and has the following parts: The mouth opens into a muscular pharynx which has two horny, masti- catory organs, which move laterally upon each other. Succeeding this pharynx is a narrow oesophagus of variable length, which leads to a stomachal (Outlines, &c., p. 88, fig. 82, B.), is founded, un- dly, upon supposition, and not upon real ob- servation.* 1 The vibratile disc of Conochilus has upon its centre, four cylindrical processes, terminating usu- ally by a bristle, and quite resembling antennae. The two or four styles projecting from the front of Synchaeta, are probably of the same nature. 2 The eye-speck is simple with Euchlanis, No- tommata, Synchaeta, Cycloglena, and Brachio- nus ; double with Conochilus, Megalotrocha, Diglena, Rotifer, and Philodina ; with Eosphora, there are three, and with Sguamedia, four ; while Hydatina, Enteroplea, Ptygura, Tubicolaria, and the adult Flosculariae, have none at all. 8 Ehrenberg, who was the first to regard these red dots as eyes, has given their intimate structure in none of his writings; this is the more to be *[§ 134, note 1.] Gosse (Ann. Nat. Hist. 1850, p. 21) describes the nervous system of Asplanchna priodonta as follows : ‘ Each of the three eyes rests -n a mass that appears ganglionic; the clubbed masses at the lateral apertures are probably of the same character ; and the interior of the body con- tains a number of very delicate threads, floating freely in the contained fluid, which have thickened knobs here and there, especially where they anas- tomose.”” Leydig (Zur Anat. und Entwickelungsgeschichte der Lacinularia socialis, in Siebold and Kélliker’s Zeitsch. Feb’y, 1852, p. 457) describes a very pecu liar nervous system with Lacinudaria, consisting of: “1, A ganglion behind the pharynx, composed 13 regretted since Dujardin has not regarded them as visual organs (Infusoires, p. 591). He sup- ports this view by the fact that they disappear with the adult individual ; but this objection will appear valueless when it is remembered that this is also true of certain parasitic Crustacea. At all events, the small ocular dots of Conochilus, Rotifer, and Philodina, are nicely-defined organs surrounded with a solid capsule, and appear to me wholly dif- ferent from the diffused masses of red pigment which Ehrenberg has erroneously taken for eyes with the Infusoria. The disproportionate size of the red dots which Ehrenberg (Die Infusionsthier- .chen, Taf. LI, LIT. LVI.) has figured with Notom- mata forcipata, Synchaeta baltica, Cycloglena, and Kosphora, lead one to suppose that they are: only collections of pigmentary granules. of four bipolar cells with their processes. 2. A gan~ glion at the beginning of the caudal prolongation, similarly composed of four Jarger ganglionic cells and their processes.” But, that these parts belong to the nervous system, appears by no means posi- tive ; for, as, this observer candidly observes, and it is, I think, a capital comment on this whole class of study: ‘‘ That these cells, with their radiat- ing processes, are ganglion globules and nerves, is w conclusion drawn simply from the histologicat constitution of the parts, and from the impossibility of making anything else out of them, unless in- deed, organs are to be named according to our mere will and pleasure.” — Ep. 146 $ 186. THE ROTATORIA. dilatation. This dilatation is continuous into an intestine which opens exter- nally by an anus.. The mouth is always between the rotatory organs, so that it receives what is drawn in by their vortical action, — the animal swallowing or re- jecting the particles at will. The pharyngeal masticatory apparatus is round, and composed of two jaws having one or several teeth, which are brought together laterally by the action of special muscles. ® Usually these jaws are formed of two knee-shaped divisions (Processus anterior and posterior). The posterior division gives insertion to the masti- catory muscles, but the anterior terminates with a tooth,® or as a multi- dentate apophysis.” With some which have this last arrangement, the two jaws are formed of three horny arches, and noted for their stirrup-like form. Two of these arches (Arcus superior and inferior), form the arched portion of the stirrup, pointing inwards, while its base is formed by the third arch (Arcus externus), pointing outwards. The masticatory muscles are inserted upon the inferior arch, and move against each other — the. transversely-arranged teeth passing over the other two. With the multidentate Monotrocha, and Zygotrocha, the pharynx rests always in the same locality; but with the unidentate Polytrocha, it can move up and down, and even be protruded through the mouth. In this last case, the teeth serve.as pincers for the seizure of food. The intestine usually traverses the cavity of the body in a straight line, rarely loop- ing, and is lined throughout with ciliated epithelium. From the stomachal dilatation to a point near the anus, its walls are very thick. The walls of the stomach and intestine are formed of large cells with a colorless nucleus, and which, as they contain a brownish or greenish granular substance, are of an hepatic nature. With most species, two caeca, rarely more, with thick walls and lined with ciliated epithelium, open on the right and left of the beginning of the stomach. Their walls are also composed of large cells, which, as they differ widely from the hepatic ones by their colorless contents, may perhaps serve the function of salivary glands or pancreas.” The term Rectum has been given to a short and terminal portion of the intestine, which has thin walls, capable of being widely distended by faeces. Its orifice is excretory not only of the faeces, but also of the contents of the genital organs and of the aquiferous system— and may therefore be regarded as a cloacal as well as an anal opening. It is nearly always at the base of the caudal extremity. 1 The tentaculiform, rotatory organs of Stephano- ceros, are also used for the seizure of food; see Ehrenberg, Abhandl. d. Berl. Akad. 1832, Taf. XI. fig. 1, e., also, Die Infusionsthierchen, Taf. XLV. fig. II. 5. 2 For the structure of the teeth, see Ehrenberg, Abhand. d. Berl, Akad. 1831, p. 46, Taf. ITI. IV. 3 Pleurotrocha, Furcularia, and many species of Notommata, and Diglena. 4 Hydatina, Euchlanis, Salpina, Anuraea, Brachionys, and many species of Notommata, and Diglena. 5 Philodina, Conochilus. 6 With Euchlanis, and Brachionus, the stom- ach is separated from the intestine by a constric- tion, and with Philodina, the intestine is of equal Lacinularia, Melicerta, and size throughout, except the rectum which is dilated. But it is coiled, especially with those which are enclosed in a carapace, as with Tubicolaria, and Melicerta, since here the anus is far in front. 7 These two pancreatic caeca are nearly always present, being wanting only with some species of Ichthydium. With Notommata clavulata, and Diglena lacustris, there are, besides these caeca which are Yong, attached to the stomach many smaller sacs, which are colorless and perhaps of the same nature. With Megalotrocha albo-flavicans, there are also two like caecal appendages entering the base of the stomach, and which are independent of the short pancreatic ones of the same locality ; see Ehrenberg, Abhandl. d. Berl. Akad. 1831, Taf. II. and, Die Infusionsthierchen, Taf. L. LIV. THE ROTATORIA. $$ 187, 188. 147 CHAPTERS VI. AND VII. CIRCULATORY AND RESPIRATORY SYSTEMS. § 187. As no sanguineous system has yet been found with the Rotatoria, it must be admitted that all the organs are bathed directly by the nutritive liquid which transudes through the intestine.® § 138. The vessels observed with the Rotatoria belong probably to the aquiferous system, which, from its structure and limited distribution, must be regarded as of a respiratory nature. In most species, a straight and riband-like organ is seen upon each side of the body, which contains a stiff, tortuous, vasculi- form canal. At the anterior extremity of these two lateral bands, their canals connect with many short lateral vessels which open into the cavity of the body, — their orifices being furnished each with a very active, vibra- tile lobule. These lateral orifices have the appearance of pyriform, or oval corpus- cles, in the interior of which, the vibratile lobule, produces the aspect, when its motions are diminished by pressure between plates of glass, of a small, flickering flame. The number of these organs varies with the species, and also, it would appear, even with different individuals of the same species. 1 The sanguineous vessels which Ehrenberg has frequently described and figured, have not ap- peared as such to Dujardin (Infusoires, p. 589), Rymer Jones (Comp. Anat. p. 125), Doyere sAnn. d. Sc. Nat. XVII. 1842, p. 201), and my- self, The so-called annular vessels encircling the body ‘of many species at regular and wide distances, and which, as he himself avows (Die Infusionsthier- chen, p. 415), are not connected by longitudinal ‘vessels, are undoubtedly only the transverse sulca- *[§ 187, note 1.] Dalrymple (Phil. Trans. 1849, p. 334) has described with Asplanchna Brightweliii what he regards as a peculiar cir- culatory system. It “consists of a double series of transparent filaments (for there is no proof of their being tubes or vessels), arranged, from above downwards, in curved or semicircular form ; sym- metrical when viewed in front. These filaments, above and below, are interlaced loop-like ; while another fine filament passes in a straight line, like ‘the chord of an arc, uniting the two looped extrem- ties. To this delicate filament are attached tags, Usually there tions, or muscles. From their extreme tenuity, it is difficult to determine the nature of the other fili- form organs in the body of the Rotatoria, and which Ehrenberg has also referred to the sanguineous system. But, equally well might they be taken for “ muscular fasciculi, ligaments or nerves.* 1 Ehrenberg was the first to point out these vibratile organs,and designated them as the inter- nal gill-like respiratory organs (Abhandil. d. Berl. Akad. 1833, p. 183). or appendices, whose free extremities are directed towards the interior of the animal, and are affected by a tremulous, apparently spiral motion, like the threads of a screw. This is undoubtedly due to cilia arranged round these minute appendices. The tags are from eight to twelve, or even twenty, in number, varying in different specimens.” He thinks these organs fulfil their function by the cil- iated tags producing currents in the fluid which fills the body of the animal. These observations are curious and deserve fur- ther attention. — Ep. 148 THE ROTATORIA. § 189. are two or three on each side, and sometimes there sre from five to eight airs,® but rarely more.® The lateral bands approach each other at the posterior extremity, and their canals join in a common, highly-contractile vesicle with thin walls, which empties externally its aqueous contents through the cloacal open- ing. kn orifice, situated usually upon the neck, and sometimes pedunculated, serves probably to introduce the water into the cavity of the body. This water enters the aquiferous system through the lateral vessels which float free in this cavity, and at last is expelled through the contractile vesicle. In this way, a constant renewal of water can occur, and the opening upon the neck may therefore be properly termed ‘a respiratory orifice or tube. There can be but little doubt that the rotatory organs also, have a respir- atory function, for their surface is covered with thin epithelium, and their cilia produce a constant change of the water. CHAPTER VIII. ORGANS OF SECRETION. § 139. Some of the Rotatoria secrete a gelatinous substance, which, hardening, forms the cells and tubes into which they can partly or wholly withdraw themselves. The organ of this secretion is yet-unknown; but the secretion appears to be derived from the posterior extremity, and especially from the cloacal opening.© 2 Notommata copeus, and syring. 8 With Notommata clavulata, and myrmeleo, the number of these organs is remarkable ; each lateral band has thirty-six to forty-eight; see Ehrenberg, Die Infusionsthierchen, Taf. XLIX. L. 4 Ehrenberg was the first to direct the atten- tion of naturalists to these two lateral bands and their contractile vesicles ; but he regarded them as two testicles with their vesiculae seminales (Abhandl. d. Berl. Akad. 1830, p. 51). The incor- rectness of this opinion, and which he has main- tained in his grand work, cannot be doubted, if it is considered that these two bands with their appendages are already developed and in activity with the young animals, and this even before they have escaped the cavity of the parental body. In all Ehrenberg’s published figures, one no- tices nothing of the flexuous canals of these or- gans, and which, therefore, he does not appear to have observed. 5 The respiratory orifice is cervical with Entero- plea, Hydatina, Diglena, and many species of Notommata; but, with Rotifer, Philodina, Brachionus, and some species of Salpina, Euch- lanis, and Notommata, it is replaced by a tube. With Actinurus, exceptionably, a simple res- piratory tube is placed under the throat ; and with Tubicolaria, and Melicerta, there are two in the same region. 1 With Conochilus, and Lacinularia, where several individuals are attached by their tails around a common centre, the nucleus of one of these colonies is formed by a loose, gelatinous sub- stance, in the cells of which these animals can par- tially withdraw themselves. With Oecistes, Tu bicolaria, Stephanoceros, Floscularia, and Lim nias, each individual occupies an isolated anc more or less hard gelatinous tube (Ehrenberg, Die Infusionsthierchen). The tubes of Melicerta, of which Schaffer has given an excellent figure (Die Blumen-polypen der siissen Wasser 1755, Taf. I. II.), are very remarkable, and according to Ehren ~ berg, are composed of brown polygonal cells which are excreted through the cloacal opening and glued together (Die Infusionsthierchen, p. 406). $ 140. THE ROTATORIA. 149 CHAPTER IX. ORGANS OF GENERATION. § 140. Although it is certain that the Rotatoria propagate only by genital organs, yet the female organs only are yet well known. These consist of a single or double ovarian tube of variable length, situated upon the sides of the intestinal canal at the posterior part of the cavity of the body, and opening into the cloacal cavity through a short oviduct. never develop but a few eggs at a time. oval and surrounded by a simple, solid, colorless envelope. These ovaries The mature eggs are always They contain a finely granular and usually colorless vitellus, in which there is a distinct germinative vesicle. parous.” Many species are ovigerous, but a few only are vivi- It would be naturally supposed that these animals, which have such dis- tinct female organs, would have also those of the other sex. But as yet the most minute researches have failed to detect them. It is therefore doubt- ful whether these animals are hermaphrodites or of separate sexes.t 1 For the various forms of the ovaries see the classical works of Ehrenberg. With Philodina roseola, Brachionus rubens, and Mastigocerca carinata, the vitellus of the eggs as well as the parenchyma of the body is of a reddish color. ‘With those species which live in the tubes, the eggs are usually deposited in the cavity of these dast. But with Triarthra, Polyarthra, and Brachionus, they remain glued to the cloacal opening. With Philodina, the young are often hatched in the cavity of the parental: body, and are, accord- * [§ 140, note 1.) The view here expressed that the young of the viviparous Philodinae may find their escape from the body of the parent through gn opening near the anus—the oviducts being perhaps wanting — is probably correct, since, in the viviparous Aphides, where the processes of repro- duction occur likewise by a kind of gemmiparity, there are, according to my observations, no ovi- ducts proper, but the young, having fallen into the abdominal cavity, thence escape through a Porus genitalis situated near the anus. — Ep. t [End of § 140.] The discovery of distinct males with the Rotatoria is due to Brightwell (Ann. Nat. Hist. Sept. 1848) who has positively determined it with Asplanchna. Here it is about half. the size of the female, being also of a different form; it is exceedingly transparent and easily eludes observation, The testis appeared as a round yes sel situated at the bottom of the body on one side, and filled with spermatic particles. This author 13* ing to Ehrenberg (Die Infusionsthierchen p. 483), always surr d with an ex ible membrane of the ovary (uterus), But it has always appeared to me that the mature eggs of the viviparous Phi- lodinae, are detached from the ovaries and fall into the cavity of the body, where afterwards the hatched young move about. Perhaps oviducts are here wanting and the young escape from their parent through an orifice near the cloacal open- ing.* : 2 Admitting that there are here male genital organs, the respiratory tube upon the neck of thinks also that he observed a well-defined intro- mittent organ connected with the testis, and a passage for its extension from the body of the animal. In verification of this observation it may be men- tioned that Brightwell observed the actual coitus between the sexes, and Gosse (loc. cit. p. 22) has witnessed the development of the males from the ovum. Huczley, on the other hand (Quat. Jour. Mic. Se. No. I. Oct. 1852, p. 1), has found with Lacin- ularia no trace of a male individual, but in some specimens he observed singular bodies which answered precisely to Kélliker’s description of the spermatic particles of Megalotrocha. He says, “They had a pyriform head about 1-1000 in. in diameter by which they were attached to the parietes of the body, and an appendage four times as long which underwent the most extraordinary contor- tions, resembling however a vibrating membrane THE ROTATORIA. § 141. § 141. Their embryonic development occurs, as in most invertebrate animals, through a complete segmentation of the vitellus; and the embryonic cells then appear in the segmented portions. The newly-hatched embryo has already rotatory and masticatory: organs, eye-specks, &c., and the general form of the adult animal.} many species was formerly taken for a penis. But the incorrectness of this view has since been seen, for no one has here observed the copulatory act.’ According to Ehrenberg, who regards these ani- mals as hermaphrodites, certain parts of the aquif- erous system represent the male organs. He regards the two lateral bands as testicles, and their inferior extremities as vasa deferentia, while the contractile vesicle is the vesicula seminalis. But these organs contain only an homogeneous aqueous fluid, in which there is at no time anything like spermatic particles ; moreover they are fully developed in the young individuals which then have no trace of female organs. It would be wholly anomalous that these ani- mals should constantly secrete sperm during their whole life. One would therefore wholly assent to the doubts of Dujardin (Infusoires, p. 587), upon this view of Ehrenberg, and some contradictions into which this last has fallen upon this subject, have been noticed by Doyére (Ann. d. Sc. Nat. XVII. 1842, p. 199). Kélliker has also thought this view unfounded, and has sought to remove the doubts by a search after the spermatic parti- cles. He regards as such, with Megalotrocha albo-flavicans, the peculiar trembling bodies which he has seen in the cavity of the body, since they are composed of a pryiform body, to which is attached a movable tail. These bodies he affirms animals (Froriep’s neue Not. No. 28, 1848, p.. 17). But this whole observation is somewhat sus-- picious, for Kadliker has very probably confounded the vibratile lobules of the aquiferous system with the spermatic particles, and of which there are four with Megalotrocha in the anterior extremity. The observation of R. Wagner (Isis, 1832, p. 386, Taf. IV. fig. 1, 7) is particularly worthy of atten- tion, for followed out, it might lead ‘to the discovery’ here of male genital organs. He has described peculiar eggs, found frequently by him with Hy- datina senta, and whose whole. surface is covered with very fine, thickly-set hairs. He has regarded. these as in their first stages of development, although Ehrenberg (obpandl: d. Berl. Akad. 1835, p. 154, and, Die Infusionsthierchen p. 415), has taken this villous envelope for an alga of the genus Hygrocrocis. But these villous envelopes have always reminded me of the masses of sperm- atic particles in the testicles of leeches and which have been figured by Henle as whitish felt-like globules (Muiller’s Arch. 1835, p. 584, Taf. XIV. fig. 6. a). [Additional Note.] Kélliker (Neue Schweiz. Denkschr. VIII. Taf. I. fig. 31, a.) having since figured the spermatic particles of Megalotrocha alboflavicans, my former view that he had con- founded these with vibratile organs, is incorrect.” 1 Kélliker was the first to observe the complete are developed in round cells, often l d, and he has often counted ten to twenty in the same individual. As he also asserts to have seen eggs at this time in the same individual, this would cer- tainly be a proof of the hermaphroditism of these more than the tail of a spermatozoon.” He very justly concludes that they cannot at present be definitely regarded as spermatic particles. — Ep. * [§ 140, note 2.] The subject of the form and character of the spermatic particles of the Rotatoria is quite interesting, as it may perhaps throw some light on the position of these animals in the animal kingdom. As yet, however, we have very few observations, and even these are not fully defi- nite. ~ Schmidt (Vergleich. Anat. &c. p. 268, note) speaks of the spermatic particles of Zuchlanis macrura, as being cercaria-form. Leydig (Siebold and Kélliker’s Zeitsch. III. Hit. 4, p. 471) has given those of Lacinularia as composed of a nuclear body from which radiate many tails, like these particles with the Decapods, See Taf. XVII. fig. 2.— Ep. + [End of §141.] We are indebted to Leydig (Zur Anat. u. Entwickelungsgesch. d. Lacinularia socialis, in Siebold and Kéiliker’s Zeitsch., III. p. tion of the eggs, with Megalotrocha (Froriep’s neue Not. loc. cit.). It wholly escaped the observation of Ehrenberg amid his numerous researches upon the eggs of these animals; see Abhandl. d. Berl. Akad. 1835, p. 152.$ 452) and to Hualey (loc. cit. p. 11-15), for extend- ing our knowledge in this direction. They have carefully observed the development of Lacinu- laria, and the phases correspond exactly with those of Megalotrocha as described by Kélliker. But beside this ordinary mode of reproduction, they have observed another which is a sexual and analogous if not identical with what has beet observed with some of the lower Crustacea (see infra § 292), — propagation by the so-called hiber- nating eggs. Their observations throw light on the whole of this interesting subject, and have fully confirmed me in my previous conjectures that these “Ova? are only gemmae having their exact repre- sentative in the bud-like eggs of the viviparous Aphides. — Ep. t[§ 141, note 1.] Kéllixer’s observation above- mentioned on Megalotrocha, has since been con- firmed by Leydig (Isis, 1848, p. 170) who has observed it likewise with Notommata and Euch- lanis.— Ep. BOOK EIGHTH. ANNELIDES. CLASSIFICATION. ' § 142. Tur ANNELIDES are distinguished from all other worms by their ventral, ganglionic cord, and by their annulated body, at the two extremities of which there is a mouth and anus. They resemble the Arthropoda, but at the same time differ from them in having a completely closed vascular sys- tem, and in wanting articulated, locomotive organs. The epithelium of their body is not ciliated except where it covers the external branchiae. The Nemertini, which have hitherto been classed among the Turbellaria, belong more properly to the Annelides, since their body is more or less dis- tinctly articulated, and its parenchyma closely resembles that of the Hiru- dinei. Moreover, the power which many of them have to divide sponta- neously into many segments, is another affinity with various Annelides. It will therefore appear proper to unite the Nemertini with the other Anne- lides in the following manner : ® ORDER I. APODES. Body without bristles. SUB-ORDER I. NEMERTINI. Posterior extremity of body without a sucker; cephalic extremity often provided with lateral respiratory fossa. 1 Since Kelliker (Verhandl. d. Schweiz. naturf. visit at Trieste in 1847, been convinced that Gesellsch. zu Chur. 1844, p. 89) and Quatre- these animals should be classed among the Tur- Jfages (Ann. d. Sc. Nat. VI. 1846, p. 173) have _ bellaria, and that they especially deserve this name published their researches on the anatomy of since their entire body is covered with-very dis- the Nemertini, I have, also, during my last tinct vibratile cilia. — Additional note. 152 THE ANNELIDES. §$ 142. Genera: Tetrastemma, Polystemma, Micrura, Notospermus, Meckelia, Polia, Nemertes, Borlasia. SUB-ORDER II. HIRUDINEI. Posterior extremity of body provided with a sucker. Genera: Branchiobdella, Prscicola, Clepsine, Nephelis, Haemopis, Aulaco. stomum, Sanguisuga, Pontobdella. ORDER Il. CHAETOPODES. Body provided with bristles. — SUB-ORDER III. LUMBRICINI (ABRANCHIATI.) Body without feet. Genera: Chaetogaster, Enchytraeus, Nais, Lumbriculus, Euaxes, Saenu- ris, Lumbricus, Sternaspis. SUB-ORDER IV. CAPITIBRANCHIATI. Body provided with feet; branchiae situated upon the cephalic ex- tremity. Genera: Siphonostomum, Chloraema, Amphicora, Serpula, Sabella, Am- phitrite, Terebella. SUB-ORDER V. DORSIBRANCHIATI. Body provided with feet; branchiae situated upon its segments. Genera: Arenicola, Ammotrypane, Chaetopterus, Aricia, Aricinella, Cir- ratulus, Peripatus, Glycera, Goniada, Nephtys, Alciopa, Syillis, Phyllo- doce, Hesione, Lycastis, Nereis, Oenone, Aglaura, Lumbrinereis, Eunice, Amphinome, Sigalion, Polynoé, Aphrodite. BIBLIOGRAPHY. Pallas. Miscellanea zoologica. Hague, 1766, p. 72. O. F. Miller. Von den Wirmen des stissen und salzigen Wassers. Copenhagen, 1771. Savigny. Description de Egypte. Histoire Naturelle. Tom, XXT. 1826. Annelides, Also, Isis, 1832, p. 937. a ae Monographie de la famille des Hirudinées, Morren. De lumbrici terrestris historia naturali, nec non Anatomia. Bruxelles, 1829. Paris, $ 142. THE ANNELIDES. 153 7 Andouin et Milne Edwards. Classification des Annélides, et descrip- ‘tion des espéces qui habitent les cétes de la France, in the Annales des Sciences. Tom. XXVIL-XXX. 1832-33, but published separately under the title, Recherches pour servir a Uhistoire naturelle du littoral de la France. Tom. II. Paris, 1834, Ehrenberg. Symbolae physicae. Phytozoa turbellaria. Mune Edwards. Cyclopaedia of Anatomy and Physiology, vol. 1, 1836, Art. Annelida. Grube. Zur Anatomie und Physiologie der Kiemenwiirmer. Kénigs- berg, 1838; also, Aktinien, Echinodermen und Wiirmer des Adriatischen und Mittelmeers, Konigsberg, 1840. Orsted. Grénlands Annulata dorsibranchiata. Kjébenhaven, 1848. Annulatorum Danicorum conspectus. Fase. I. Maricolae. Hafniae, 1843. Entwurf einer systematischen Eintheilung und speciellen Beschreibung der Plattwiirmer. Copenhagen, 1844, Hoffmeister. De vermibus quibusdam ad genus lumbricorum pertinen- tibus. Berolini, 1842. Rathké. Zur Fauna der Krim. St. Petersbourg, 1836, p. 117. De Bopyro et Nereide. Rigae, 1837. Beitrage zur vergleichenden Anatomie und Physiologie; in the Neuesten Schriften der Naturforschenden Gesell- achaft in Danzig, IIT, Hft. 4, 1842, p. 56. Beitrage zur Fauna Norwe- gens; in the Nov, Act, Acad, Nat, Cur. XX. pt. 1. 1848, p. 149. ADDITIONAL BIBLIOGRAPHY. Besides the references in my notes, see the following writings: Moquin-Tandon. Monographie de la Familie des Hirudinées. Nouv. ‘Ed. revue et augmentée, accompagnée d’un Atlas de 14 planches gravées et coloriées. Paris, 1846. Schmidt. Neue Beitrage zur Naturgeschichte der Wiirmer. Jena. 1848. {zweiter Abschnitt, Ringelwiirmer). Quatrefages. tudes sur les types inférieurs de l’embranchement des Annéles, containing: Memoire sur la Familie des Hermelliens, Ann. d. Sc. Nat. 1848, X. p. 1.; Sur la Circulation des Annélides, Ibid. XIV. 1850, p. 281; Sur la Respiration des Annélides, Ibid. XIV. 1850, p. 290; Mé- moire sur le Systeme Nerveux des Annélides, Ibid. XIV. 1850, p. 329; Mémoire sur le Systéme Nerveux, et les affinities et les analogies des Lom- bries et des Sangsues, Ibid. XVIII. 1852, p. 167; Mémoire sur le Bran- chellion de D’Orbigny, Ibid. XVIII. 1852, p. 279. Note sur le Systéme Nerveux et sur quelques autres points de |’Anatomie des Albiones, Ibid. XVIII. 1852, p. 328. Mémoire sur l’Embryogénie des Annélides. Ibid. X. 1848, . 153. . Leydig. Zur Anatomie von Piscicola geometrica mit theilweiser Ver- gleichung anderer einheimischer Hirudineen, in Stebold and Kelliker’s Zeitsch. I. 1849, p. 103. — —Ep. + [ § 164, note 1.] See also Leydig, Siebol dand Kélliker’s Zeitsch. 111. Hft. 3, p. 318, and Quatre- Jages, Ann. d. Sc. Nat. XVIII. 1852, p. 298 (Branchellion).—Eb. 178 $$ 165, 166. THE ANNELIDES. With the Nemertini, and Branchiati, the sexes are upon separate individ- uals, and the genital organs are composed simply of testicles and ovaries. § 165. The structure of the genital organs of the Nemertini is yet quite obscure. Th2 few researches hitherto made only furnish the general result that the sexes are separate. , There are numerous glandular follicles situated laterally in the paren- chyma of the body between the skin and the intestinal canal, which are closely aggregated and serially arranged. With some individuals, these follicles contain eggs, and with others, sperm. ‘They ought, therefore, to be regarded as ovaries and testicles. Each follicle opens separately upon the surface of the body.” There are very contradictory statements as to whether these animals have, or have not, copulatory organs. According to some Naturalists, the worm-like organ, concealed in a canal extending along the back, and which, with both sexes, is often protruded and moved actively about, ought to be regarded as an excitatory organ, — although no connection between it and the testicles or ovaries, has as yet been found. According to others, it is a proboscis unconnected with the genital organs. § 166. | The disposition.of the genital organs of the Hirudinei and Lumbricini, is essentially different. The first have only two simple genital openings, — one male, the other female, both situated, one after the other, upon the median line of the ven- 1 See Duges, Ann. d. Sc. Nat. XXI. 1830, p. 76, PL. II. fig. 5 (Polystemma (Prostomum) arma- zum) ; Johnston, Mag. of Zool. I. p. 532, Pl. XVIT. fig. 2°*, 6°*, Pl. XVIII. fig. 3° (Wemertes and Borlasia) ; Orsted, Entwurf. einer Beschreib. d. Plattwirm. p. 22, Taf. III. fig. 41 (Tetrastemma waricolor)} Kélliker, Verhandl. d. schweiz. na- turf. Versamml. zu Chur. p. 91 (Wemertes); and Rathké, Danzig. Schrift. loc. cit. p. 98 (Borlasia striata). This last author has not seen the orifices of the genital organs. Quatrefages (Régne anim. illustr. loc. cit. Pl. XXXIV. fig. 1, n.n.) did not see them with Nemertes Camilla, and Johnston is also silent on this subject. According to Orsted (Entwurf. &c. loc. cit. p. 25, Taf. IIL. fig. 47, of Notospermus flaccidus) the Nemertini secrete from the whole surface of their body, a gelatinous mucus, which surrounds the eggs, and thus forms an envelope into which they can draw their bodies. Something similar to this occurs with the Lumbri- cini and Hirudinei. See below. 2 The Nemertini being of distinct sexes, this or- gan can be regarded neither as a penis, nor as an everted spermatic vessel, as Huschke has done Asis, 1830, p. 682, Taf. VII. fig. 5). More prop- erly could it be considered, with Orsted (Entwurf. &Xc. p. 25), as an excitatory organ; although Rathké «Danzig. Schrift. loc. cit. p. 100, and Nov. Act. Acad. Nat. Cur. XX. p. 233) regards it as of a tactile, and Kélliker of a prehensile nature (Verhandl. d. schweiz. p. 90). Other observers agree with Khrenberg (Symb. phys. loc. cit.) that it is an in- destine and an everted oesophagus, its orifice being @ mouth ; but this is undoubtedly erroneous. With’ Polystemma armatum (Duges, Ann. d. Sc. Nat. loc. cit. p. 75, Pl. IL. fig. 5) Tetrastemma_vari- color (Orsted, Entwurf. &c. p. 23, Taf. ITI. fig. 41), and Nemertes (Johnston, Mag. of Zool. I. p. 630, fig. 2; Quatrefages, Régne anim. illustr. loc. cit. Pl. XXXIV. fig. 2,:and Kélliker, Verhandl. d. schweiz. &c.) there is at the centre of this organ a dart pointing forward, which is horny, atcord- ing to Dugés, and calcareous, according to Orsted. On each side of this dart, there is a reservoir of many others, smaller and yet imperfect, destined, probably, to replace the former when lost. Dugés, Johnston, and Quatrefages, who regard this or- gan as an intestinal canal, and Kélliker, who con- siders it prehensile, all regard these darts as a kind of teeth; but Orsted thinks they serve to excite the genital organs. For my part, they involunta- rily remind me of the darts of the Helicina. {Additional Note.) —I have now satisfied myself ' upon living individuals of I’etrastemma, that the eggs can escape from the visceral cavity through numerous lateral openings in the wall of the body Iam also satisfied that with the Nemertini, the walls of the digestive canal (the middle body-cavity according to Quatrefages) are not the points of departure of the genital organs, as Quatrefages thinks, and who also would regard as a digestive tube the snout of these animals, an organ which is yet enigmatical. The very detailed figures which this naturalist has given (loc. cit.) of the walls of the digestive canal of these animals, present nothing like an ovary, and show no trace of the presence of germs. $166. THE ANNELIDES. 179 tral surface. The posterior opening connects with a short muscular canal which may be regarded as a reservoir of eggs. _ From the base of this reservoir, a narrow spiral canal passes off, and bifurcating into two oviducts, terminates with two round ovaries, From the anterior opening, a long filiform penis may be protruded, which, when not erected, lies spirally concealed in a bulbous muscular sheath. A Ductus ejaculatorius extending from the seminal vesicles, opens into each side of this sheath. These seminal vesicles are formed each by a kind of continuation of the vas deferens into a varicose tortuous canal, which lies in the midst of a dense cellular tissue. The Vasa deferentia are narrow, and passing backwards along the sides of the body, receive upon their internal surface the short excretory ducts of the five, nine, or twelve pairs of ae isolated testicles, which form a double row near the ventral cord. With many Hirudinei, a portion of the skin is connected with the sexual function. Such is the case with Nephelis, with which numerous cutaneous glands are developed upon the back and belly near the female genital opening. The skin soon has a bloated, transparent appearance, so that the animal appears to have a girdle about its anterior extremity. Before the deposition of the eggs, these glands secrete a substance which hardens in water, and surrounds the body of the animal like a horny belt. This belt is filled with a greater or less quantity of eggs; the animal then withdraws, or slips out from’ it, while its two extremities are closed up by its own elasticity ; but the embryos developed in this egg-capsule are not thereby prevented from making their escape. — The Sanguisugae form cocoons in a similar manner; but they are sur- rounded with a very thick, spongy substance.” The various species of Clepsine form sac-like capsules for their eggs, and which they usually carry about with them, attached under their belly, —shielding them with their body at the approach of danger. five pairs of these organs ; with Haemopis, eight ; and with Aulacostomum, twelve (Moquin-Tan- don, Monogr. loc. cit. Pl. III. fig. 8; Pl. I. fig. 3, 1 See Brandt, Mediz. Zool. IT. p. 252, Taf. XXTX. A. fig. 45, 465; Moquin-Tandon, Monogr. loc. cit. p. 80, Pl. I.-III.; Leo, Miiller’s Arch. 1835, p. 424, Taf, XI. fig. 10 (Sanguisuga, Aulacosto- mum, Nephelis, Pontobdella, and Piscicola. According to the careful researches of Filippi qLettera sopra l’anat. e lo sviluppo delle Clepsine, p. 16, Tav. I. fig. 5), Grube (Untersuch. tib. d. Ent- wickl. d. Clepginen. p. 6, Taf. IIT. fig. 3), and Fr. Miller (Miller's Arch. 1846, p. 138, Taf. VIII.), the two ovaries of Clepsine and Nephelis, consist of long flexuous cords surrounded by two more or dess long muscular sheaths, which are uninterrupt- edly continuous into the oviducts ; they receive the ‘eggs as they are detached from the ovaries, and pass them along by peristaltic movements. 2 Sanguisuga has nine pairs of testicles (Brandt Med. Zool. II. p. 252, Taf. XXIX. A. fig. 32-44). The Vasa deferentia of the seven pairs with Pis- cicola are dilated before reaching the two seminal vesicles into two long and very flexuous tubes (Epi- didymis, according to Leo, loc. cit. 1835, p. 423, ‘Taf. XI. fig. 10). With Pontobdella, there are * [§ 166, note 2.] For many valuable details on the genitalia of the Hirudinei, see the often-quoted and valuable works of Leydig, loc. cit. p. 120. It ins histol 1, as well as ] results. ding to him, Pi. /a has six, and not seven (£0) pairs of testicles. — Ep. A Pl. IL. fig. 10). With Nephelis, the arrangement is different, there being on each side of the poste- rior part of the body, numerous testicular vesicles united in a botryoidal manner ; see Moquin-Tan- don, Monogr. loc. cit. Pl. III. fig. 4.* 8 See Rayer, Ann. d. Sc. Nat. IV. 1824, Pl. X. fig. 1-6, and Moquin-Tandon, loc. cit. Pl. VI. fig. 4,e-h. These cocoons are often found as brown scales, glued to aquatic plants. Piscicol/a forms similar cocoons, but they never have more than one egg each ; see Leg, loc. cit. p. 425, Taf. XI. fig. 6 ; ee Brightwell, Ann. of Nat. Hist. IX. 1842, p. 11 4 See Rayer, loc. cit. Pl. X. fig. 10, and Moguin- Tandon, loc. cit. Pl. V. According to Wedeke (Froriep’s neue Not. No. 452, 1842, p. 183), the medicinal leech ejects from the mouth as a scum, the spongy envelope of these cocoons. 5 See Grube, Untersuch. tiber die Entwick. @ Clepsinen, 1844, p. 1. t (8 166, note 3.) See, for an histological exami- nation of these genital glands in Piscicola, Ley- dig, loc. cit. p. 122, Taf. IX. fig. 43, e. 49, a.b. c. — Eb. 180 THE ANNELIDES. § 167, § 167. j The genital organs of the Lumbricini are very difficult of dissection ; for often those of both sexes are intimately united together into a common mass. It is certain, however, that the male and female orifices are always in pairs and situated at the anterior extremity of the body, near the ven- tral median line.” These orifices communicate with more or less numerous glands, sacs, and” pyriform or cylindrical vesicles. Their nature as testicles, ovaries or sperm-receptacles, is known only hy their contents. As yet it has been possible to trace only very imperfectly their excretory ducts. With some, two of these caecal organs have been observed intersuscepted in each other. The internal one contained sperm- atic particles, and should therefore be regarded as a testicle; while the outer one contained at its base, eggs and egg-germs, and cught therefore to be taken for an ovary.® The larger Lumbricini appear to be without copulatory organs, the collar situated back of the genital orifices, taking their place. With many, it is situated chiefly on the back, but terminates on the belly with two long lateral swellings, which, during coition, seize those of the other individ- ual.® This collar, moreover, is composed of a mass of glandular follicles, which copiously secrete, during the sexual period, a white, viscous liquid. It is then very fully developed, but at other periods it is scarcely visible. | The belt which is developed near the genital openings of the smaller Lum- 1 With Lumbricus terrestris, the two anterior‘ genital openings are male, and the two posterior, female. These have been figured by Montegre (loc. cit. fig. 2, a. .), Leo (De Struct. Lumbr. ter- restr. Tab. I. fig. 2), and by Morren (loc. cit. Tab. III. fig. 2). With Saenuris, and Nais, I have also found these two pairs of genital openings. 2 This invagination of the testicle in the ovary has been distinctly observed by me with Saenuris variegata, and Nats proboscidea. From H. Meckel’s late researches upon the very compli- cated genital apparatus of Lumbricus terrestris, it appears that there are three pairs of seminal vesi- cles and testicles ; these last being intimately joined with as many ovaries (Muller’s Arch. 1844, p. 480, Taf. XIII. fig. 12). It is probable that here the testicles and ovaries are also invaginated, and that the vesicles which have usually been taken for testicles are only vesiculae seminales; see Mor- ren, loc. cit. p. 175, Tab. VII.-X. and T'reviranus, in his Zeitsch. f. Physiol. V. p. 154, Taf. VII. How- ever, as yet I have been unable to trace to their ter- mination, the excretory ducts of the testicles and ovaries which are invaginated together. This point is all the more difficult, for, as Duges appears to represent (Ann. d. Sc. Nat. XV. 1828, p. 328, Pl. IX. fig. 2, or Isis, 1830, Taf. IIL. Tab. 9, fig. 2), the vas deferens is probably invaginated in the oviduct. Many observers have gone so far as to think that the eggs having escaped from the ovary, and fallen into the cavity of the body, pass gradually to its posterior portion, and are there evacuated through invisible openings. On this account, several of them have taken for eggs and embryvs, the collections of horny spines, and vibrios, which are often found in these animais. See above, § 145, note 1; and E. Home, Lect. on Comp. Anat. IV. 1823, Pl. CXLIX. I have always been astonished that, at the epoch of procreation with Saenuris, Euazes, and Nais, the two anterior genital openings should i bundles of spermatic particles, but never their cells of development. Dugés has made a similar obser- vation with his Nais filifoarmis (Ann, d. Sc. Nat. loc. cit..p. 320, Pl. VI. fig: 2), only he dees not specify the contents of the organs. Menge, also, | has observed these’ two caeca with Euaves, but he unhesitatingly regards. them. as testicles (Wieg- mann’s Arch. 1845, I. p. 32, Taf. IIL. fig. 2, aa. fig..3). Never having seen any connection between these caeca and the testicles behind them, I am disposed to think that the two posterior genitah openings of some Lumbricini, are the common ori- fices of the invaginated testicles and ovaries, while the anterior caeca, which are filled at certain times with sperm, are two isolated Receptacula seminis. During the mutual copulation, the sperm will pass- from the testicles into these reservoirs, in order to be used during the subsequent deposition of the eggs. From Hoffmeister’s description (Die bis jetzt bekannt. Arten aus der Familie der Regenwiirmer,. 1845, p. 15) of the copulatory act with Lumbricus agricola, it would appear that the sperm remains equally distant from the female organs, being re- ceived into special fossae, which correspond per- haps to the Receptaculaseminis. Nais probos- cidea, although having a pair of genital openings, has only one testiculo-ovarian canal, both of which although invaginated, have a very active and inde-~ pendent peristaltic action. They are bifurcated an~ teriorly. See Gruithuisen (Nov. Act. Acad. Nat. Cur. XI. p. 246, Tab. XXXYV. fig. 4, 5), who has very correctly perceived the eggs in the bottom of the ovarian sac, but not the nature of the invagi- nated testicular canal. th Lumbricus olidus,.he two copulating individuals seize each other su iightly py their col- lars, that each of these animais completely envel— ops the other by this organ ;, see Hoffmeister, in - Wiegmann’s Arch. 1848, I. p. 190, and, De ver~ . cate with two caeca which contain sperm and long mibus quibusdam, Tab. I. fig. 30. § 168. THE ANNELIDES. 181 bricini at this period, is of an analogous nature. It is also composed of numerous cutaneous glands, closely agyregated, and extending completely over many segments of the body.” The secretion of this collar is like that observed with the Hirudinei, probably for the formation of cocoons. But these cocoons differ from those of the Hirudinei in having the place of their opening prolonged into a long, narrow neck.” § 168. The Branchiati resemble the Arthropoda in their annulated body, their distinct head endowed with organs of sense, the structure of their nervous system, and the development of their locomotive organs; but, from the simplicity of their locomotive apparatus, and the complete absence of cop- ulatory organs, they would be carried towards the Zoophytes. Here the sexes are separate, and the genital organs of both the Capiti- branchiati, and Dorsibranchiati, appear as simple glandular bodies, ovaries or testicles, which project from the ventral surface into the cavity of the body between the fasciculi of the cutaneous muscle.” At the sexual period, they are filled with eggs, or spermatic particles, although at other times they ean scarcely be seen. Neither the testicles nor the ovaries have excretory ducts which open upon the surface of the body. The sperm and eggs escape into the cavity of the body, which, during this period is thereby filled throughout. It is possible that the scarcely visible orifices said to be concealed be- 4 Saenuris, Nais, &c.; see Gruithuisen, loc. cit. Tab. XXXV. fig. 5, b.b. 5. With the large species of Lumbricus, each co- coon has from one to six eggs (L. Dufour, Ann. d. Sc. Nat. XIV. 1828, p. 216, Pl. XIL. B. or, Froriep’s Notiz. No. 472, 1828, p. 149, fig. 13-16 ; and Haf- meister, De vermibus quibusdam, Tab. I. and Die Arten aus der Familie, &c., p. 16, 25, 42). With the smaller L ini, as with S is, Euares, Nais, &c., the cocoons contain nearly always five to eight eggs (Duges, loc. cit. XV. Pl. VII. fig. 5, Nais). Most of these cocoons have appendages by which they are attached to vegetables and other bodies. Hoffmeister (Die Arten aus der Fam. &. p. 42, fig. 9, c.) has figured a very remarkable husk-shaped cocoon of a new species, Criodrilus lacuum. 1 See Treviranus, Zeitsch. f. Physiol. III. 1827, p. 165, Taf. XIII. fig. 17, 18 (Aphrodite) ; Rathké, De Bopyro et Nerejde, p. 39, Tab. II. fig. 12, 1. ‘Nerets), and, Danzig. Schrift. loc. cit. p. 66, Taf. V. g. 6, hh. fig. 11, aa. (Amphitrite) ; Grube, Zur Anat. d. Kiemenwiirmer, p. 16, Taf. I. fig. 1, 2, m. (Arenicola), p. 44, Taf. II. fig. 6, y. z. (Bu- nice); also, Nov. Act. Acad. XX. p. 201, Tab. X. fig. 18, 15, m. (A4mmotrypane). Rathké’s and Grube’s opinion upon the presence of both male and female organs with the same individual is only an uncertain supposition, founded upon no histo- logical examination of the parts. 2 This condition of the genital glands after the pro- creative season, is the reason why, as yet, we pos- sess so few facts as to their structure. Most ob- servers, and among them Rathké¢ and Grube, are * [§ 168, note 2.] According to Quatrefages (Ann. d. Sc. Nat. X. 1848, p. 46) the sexes are sep- arate with the Hermedia. Both the testicle and the ovary consist of a delicate areolar tissue adherent to the inferior internal surface of the general cavity of the body. These genital organs are evidently tem- 16 ‘dividuals (Muller’s Arch. 1840, p. 375). of the op that the Branchiati, like the Lumbri- cini, are hermaphrodites. But Quatrefages, from -his knowledge of the development of the spermatic particles, has recognized separate sexes with the ‘most different species, thus: Zerebella, Sabella, Aricinella, Nephtys, Syllis, Glycera, Eunice, Sigalion, Phyllodoce, Nerets, and Aphrodite ; see Comp. Rend. XVII. 1843, p..423. But before this, Stannius had concluded that the sexes were separate with Arenigola, from -a difference in the contents of the cavity of the bodies of different in- The glands at the cephalic extremity of the Branchiati which live in cases, and which Grube has regarded as male genital organs, are certainly not such, for they occur with both-sexes, and do not change in size during the procreative season. (See § 161, note 4.)* 8 According to Quatrefages (Compt. rend. XVII. 1843, loc. cit.), the parent sperm-cells leave the testicle before the formation of the spermatic particles, which occurs in the cavity of the body. This is confirmed with Arenicola, by Stannius (Miller’s Arch. 1840, loc. cit.). Ac- cording to Krohn (Wiegmann’s Arch. 1845, I. p. 182), the eggs and the spermatic particles, with 4/- ciopa, are developed free in the visceral cavity, without the intervention of special organs, ovaries and testicles. Frey and Leuckart (Beitr. &c. p. 88) think they have observed the same fact with Nereis, Syllis, Phyllodoce, Aonis, Ammotry- pane, Ephesia, Hermella, Vermilia, Fabricia, and Spirorbis ; they speak of the presence of ova- ries and testicles in certain Annelides (Aphrodite, Arenicoia) as the exception. porary, for they are not found in many individuals, having, probably, quite disappeared from atrophy after the procreative period. This fact should be remembered in the study of the genitalia of other Annelides. — Ep. 182 THE ANNELIDES. $ 169. tween the feet of many Branchiati, serve for the escape of the sperm and eggs. With others, the cavity of the body opens outwardly, probably by a loss of the last.segment, especially with those which are viviparous, The water is undoubtedly the medium of fecundation, and receives the sperm from the males, probably through orifices like those which serve for the escape of eggs with the female. With the viviparous Branchiati, water filled with sperm can enter the body and fecundate the eggs through these same openings. § 169. The development of the Annelides as far as yet known, occurs after two different types; but it always commences with a-complete segmentation of the vitellus.: ; : I; With the Hirudinei, after the vitellus has divided into many large cells, a central one becomes distinguished from the others by its still further division; this becomes the digestive tube. The others, still dividing, form a primitive embryonic part in which appears the future ventral and nervous ortion. j : ’ The embryo is at first spherical, and ultimately is covered with a delicate ciliary ‘epithelium. A kind of sucker is then developed upon a certain point of its surface; this connects with the stomach, and through it is re- ceived, for food, the albumen surrounding the embryo. It then gradually lengthens, and, losing its ciliary epithelium before the escape from the egg, a sucker appears upon the posterior extremity, and it finally becomes fully developed without a Metamorphosis.® II, With the Branchiati, there is a complete metamorphosis. The seg- mentation of the vitellus is uniform throughout, and this last is finally changed into a round embryo — which, escaping from the egg, swims freely about like an Infusorium, by means of the ciliated epithelium which covers its whole body. ‘The embryo then lengthens, and the epithelium disappears 4 According to Milne Edwards’ observations upon several Capitibranchiati, as T'erebella, Ser- pula, Protula, &c., the eggs are glued together in roasses by an albuminous substance, and attached to the stones of the anterior border of their cases ; see Ann. d. Sc. Nat, III. 1845, p. 148, 161, Pl. V. fig. 1, Pl. VII. fig. 28, PI. IX. fig. 42. With Poly- noé cirrata, on the other hand, masses of eggs are attached and borne about on the scales of their body ; see Sars, in Wiegmann’s Arch. 1845, I. p. 18, Taf. I. fig..12. With the females of Exogone and Cystonereis, the eggs are situated in longi- tudinal rows upon the ventral surface ; see Orsted, in Wiegmann’s Arch. 1845, I. p. 21, Taf. IL. fig. 4, and Kélliker, in an as yet unpublished memoir for the Helvetic Society, titled: Einige Worte zur Entwickelungsgeschichte von Eunice, von H. Koch in Trieste, mit einem Nachwort von Kélliker. [Additional note.] The often-quoted memoir of Koch and Kélliker on the development of the An- * [§ 168, note 4.] According to Felix Dujar- din (Ann. d. Sc. Nat. XV. 1851, p. 298) Exogone pusilla is androgynous. Beside the well-known pediculated ovarian sacs on the ventral surface, each segment of the body, except the first two, has, with this species, a dorsal, fusiform cirrus, in which are developed spermatic particles. This ob- nelides has recently appeared in the Neue Schweiz. Denkschr. VIII.* 5 According to my friend H. Koch of Trieste (in the MS. just indicated), the eggs of a species allied to Eunice sanguinea, are developed in the cavity of the female body, whence the young escape through a rupture of its posterior extremity. 1 See F. de Filippi, Lettera sopra ]’Anatomia, e lo sviluppo delle Clepsine, Pavia, 1839, Tav. II. ; Grube, Untersuch. tiber die Entwick. d. Clepsine, p. 15, Taf. L., and Frey, Zur Entwickel. von. Nephe- lis vulgaris, in Froriep’s neue Not. No. 807, 1846, p. 228. The old observations of E. H. We- ber (Meckel’s Arch. 1828, p. 366, Taf. X. XI.) and R. Wagner (Isis, 1832, p. 398, Taf. IV.) agree: very well with those of Filippi As yet, we possess nothing upon the develop- ment of Lumbricini, whose young, as is known, like those of the Hirudinei, leave their cocoons without undergoing any metamorphosis.t servation, from its singularity, requires confirm- ation. — Ep. + [§ 169, note 1.] For the embryology of Ne- mertes, see Desor, Boston Jour. Nat. Hist. VI. p. 1. The general facts accord with those mentioned in the text. — Ep. $ 169. THE ANNELIDES. 183 except upon the belt-like parts of the two extremities. The future ante- rior extremity is directed in front during the motions of the animal, and eyes appear upon it; while the other extremity is gradually divided into segments upon which bristles and feet appear.@ While the embryos are thus acquiring the adult form, there appear upon the cephalic extremity and upon the sides of the body, tentacles, cirri, and branchiae, of forms which vary according to families, genera and species. The development of the digestive and circulatory organs occurs also with equal pace, 2 See Lovén in Wiegmann’s Arch. 1842, I. p. 302, Taf. VIL. (Nereis); Sars, Thid. 1845, I. p. 12, Taf I. fig. 1-21 (Polynoz); Orsted, Ibid. p. 20. Taf. II. peToe one) ; and Milne Edwards, Ann. da. Sc. Nat. Ill. 1845, p. 145, Pl. V.-IX., or, Froriep’s neue Not. No. 721, p. 257 (Tere- bella, Protula, and Nereis). Kaélliker (in MS. already cited) has also observed the development of an Exzogone, and of a Cystonerets, an allied ge- nus. Here the embryo is not formed through a complete and uniform segmentation of the vitellus, | but, as with the Hirudinei, the formation is preced- ed by an irregular division of that portion to be the ventral and nervous parts. He, at the same time, calls the attention to a figure of Milne Edwards, repr ing the devel of Protula, from which it would appear that other Branchiati also are developed like the Hirudinei; see Ann. d. Sc. Nat. loc. cit. Pl. IX. fig. 47.* 8 One ought therefore to be careful about form- ing distinct genera from these larval Branchiati. Thus, Sabellina brachycera, described by Du- sardin (Ann, a. 8c. Nat. XI. 1839, p. 291, Pl. VIL. * [§ 169, note 2.) or the embryology of Poly- noé, see Desor, loc. cit. p.12. It agrees closely with that of Nemertes ; see also Max Miiller, in Miller's Arch. 1851, p. 323. — Ep. fig. 6), is only a larval Terebella, as will be seen “by referring to Milne Edwards’ figures of the de- velopment of Terebella nebulosa (Ann. d. Sc. Nat. loc. cit. Pl. VII. fig. 24, 25). Anisomelus luteus, of Templeton (Transact. Zool. Soc. II. 1841, p. 27, Pl. XV. fig. 9-14), is perhaps only. a young Serpula. The absence of branchiae and _ blood-vessels which Quatrefages has noticed with many small Branchiati of which he has made new genera (as Aphlebine, and Doyeria, &c.), would lead one to suspect that they are only larvae ; see Ann. d. Sc. Nat. I. 1844, p. 18, or Froriep’s neue Not. No. 726, p. 341. H. Koch (see above, § 168, note 5) has lately observed that the young individuals found in the body of Eunice are identical with the Lumbrinereis of De Blainville. The new animal described by Muller and Busch (Miiller’s Arch. 1846, p. 104, Taf. V. fig. 3-5, and 1847, p. 187, Taf. VIII. fig. 1-3) under the name of Mesotrocha sexoculata, appears likewise to be only a young larva of an Annelid.+ + [§ 169, note 3.] See Quatrefages (Sur ’Em- bryogenie des Annélides, in Aun. d. Sc. Nat. X- 1848, p. 163). - Ep. BOOK NINTH. ACEPHALA. CLASSIFICATION. § 170. Tue Acrpuata are principally characterized in having a headless body, and a very large mantle, which so envelops the body, that there is 4 spa- cious and more or less closed cavity in which the oral and anal orifices are often entirely concealed. Their body is either wholly asymmetrical, or divided into a right and a left side. In this last case, the organs, excepting the digestive canal, are in pairs; and the two sides are perfectly symmetrical, or one is developed at the expense of the other. All Acephala are aquatic; many are perma- nently attached during life; others creep about, and a few only can swim freely. Copulatory organs are wanting throughout. ORDER I. TUNICATA. Body wholly asymmetrical and so enclosed in the mantle, that there are only two narrow openings. Famity: Ascrpraz. : Genera: A. Compositae. Didemnum, Diazona, Aplidium, Botryllus, Botrylloides, Leptoclinum, Eucoelium, Synoecium, Polyclinum, Sigillina, Perophora, Pyrosoma. B. Simplices. Clavelina, Phallusia, Rhopalaea, Boltenia, Cynthia, Chelyosoma. Famity: SaPinar. Genus: Salpa. ORDER II BRACHIOPODA. Animals which are symmetrical and bivalved, and whose widely-open mantle encloses two fringed, arm-like, protractile tentacles, $ 170. THE ACEPHALA. 185 Genera: Orbicula, Terebratula, Lingula. ORDER II. LAMELLIBRANCHIA. Animals which are symmetrical and bivalved, and whose more or less closed mantle encloses two pairs of lamelliform tentacles and branchiae. SUB-ORDER I. MONOMYA. ‘Famity: Osrracea. Genera: Ostrea, Anomia. Famity: Prctinga. Genera: Pecten, Spondylus, ‘Lima. Famity: Matgacta. Genera: Malleus, Perna, Crenatula. ‘SUB-ORDER II. DIMYA. Famity: AVICULACEA. Genera: Avicula, Meleagrina, ‘Pinna. Famity: ARcacza. Genera: Arca, Pectunculus, Trigonia, Nucula. Famity: Natapes. Genera: Anodonta, Unio. Famity: Mytimacna. Genera: Mytilus, Modiola, Lithodomus, Tichogonia. Famity: CHaMacra. Genera: Chama, Isocardia. Famity: Carpracza. Genera: ‘Cardium, Lucina, Hiatella, Cyclas, Piscidium, Tellina,.Psam=- mobia, Venus, Cytherea, Venerupis, Mactra, Lutraria, Ungulina. Famity: Pytorrpae. Genera: Mya, Solen, Solenomya, Panopaea. SUB-ORDER II. INCLUSA. Famity: TEREDINA. Genera: Pholas, Teredo. 16* 186 THE ACEPHALA. $ 170. Famity: ASpPERGILLINA. Genera, :: Aspergillum, Clavagella. BIBLIOGRAPHY. Poli. Testacea utriusque Siciliae eorumque historia et anatome. 1791-95. ; J. Rathke. Om Dammuslingen, in the Skrivter af Naturhistorie-Sels- kabet, IV. Kjébenhavn, 1797, p. 189. Cuvier. Mémoire sur l’animal de la Lingule, in the Ann. du Mus. WHist. Nat. I. 1802, p. 69. Mémoire sur les Thalides et sur les Bipho- res, Ibid. IV. 1804, p. 860. Both of these are included in his Mém. pour servir 4 Vhistoire et 4 ’anatomie des mollusques. Paris, 1817. Schalk. De Ascidiarum structura, Dissert. Hal. 1814. Savigny. Mémoires sur les animaux sans vertébres, Pt. II. 1816. Re- cherches anatomiques sur les Ascidies composées et sur les Ascidies simples. Also, Isis, 1820, lit. Anz. p. 659, Taf. XI.-—XXTI. Carus. Beitrage zur Anatomie und Physiologie du Seescheiden (Asci- diae), in Meckel’s deutsch. Arch. 1816, p. 569, and Nov. Act. Acad. Leop. Carol. X. 1821, p. 423, Tab. XXXVI. XXXVII. Cuvier. Mémoires sur les Ascidies et sur leur Anatomie; in the Mém. du Mus. d’hist. Nat. II. 1815, p. 10; also Isis, 1820, p. 387, Taf. 8, 9. Chamisso. ‘De animalibus quibusdam e classe vermium Linnaeana. Fasc. I. De Salpis. 1819. Bojanus. Ueber die Athem-und Kreislaufwerkzeuge der zweischaligen Muscheln. Isis, 1819, p. 42, Taf. I. IL., 1820, p. 404, and 1827, p. 752, Taf. IX. Eysenhardt. Ueber einige merkwiirdige Lebenserscheinungen an Ascid- jen, in the Nov. Act. Acad. Leop. XI. 1823, p. 250, Tab. XXXVI. XXXVII. Pfeiffer. Naturgeschichte deutscher Land-und Stisswasser-Mollusken. Abth. IL. 1825. 5 Unger. De Anodonta anatina. Dissert. Vindobon 1827. Carus. Neue Untersuchungen tiber die Entwickelungsgeschichte unserer Flussmuschel, in the Nov. Act. Acad. Leop. XVI. 1832, pt. I. Tab. I-IV. Meyen. Beitrage zur Zoologie. Abhandl.I.; Ueber die Salpen. Ibid. . p. 863, Tab. XXVIL-XXIX. Owen. On the Anatomy of the Brachiopoda, in the Trans. Zool. Soe. I. 1835, p. 145, Pl. XXII. XXIIL; also,‘in Isis, 1835, p. 143, and Ann. d. Se. Nat. ILI. 1835, p. 52. Deshayes. Conchifera. Cyclop..Anat. Phys. I. p. 694. London, 1836. Eschricht. _Anatomisk-physiologiske Undersdgelser over Salperne. Kjébenhavn, 1840; also, in Isis, 1842, p. 467, Taf. II. IIL, and: Anato- misk Beskrivelse af Chelyosoma Mac-Leayanum. Kjobenhavn, 1841. Miine Edwards. Observations sur les Ascidies composées. Paris, 1841. Garner. On the Anatomy of the Lamellibranchiate Conchifera, in the Trans. Zool. Soc. of London, IT. 1841, p. 87, Pl. XVITI.-XX. Neuwyler. Die Generationsorgane von Unio und Anodonta, in the Neuen Denkschrift. der allg. schweizerischen Gesellsch. f. die gesammten Naturwissensch. VI. 1842, p. 1, Taf. L-IIL $171. THE ACEPHALA. 187 Vogt. Anatomie der Lingula anatina. Ibid. VII. 1843, p. 1, Taf. I. IT. Van Beneden. Mémoire sur ’Kmbryogénie, l'Anatomie et la Physiologie ee cae simples, &c., in the Bullet. de l’Acad. royale de Belgique, - No. 2. ADDITIONAL BIBLIOGRAPHY. Kolliker. Ueber das Vorkom. d. Holzfas. im Thierreich., in the Ann. d. Sc. Nat. 1846, p. 198, Pl. V.-VII. Van Beneden. Recherches sur lEmbryogénie, |’Anatomie, et la Physi- hg des Ascidies simples, in the Mém. de Acad. Roy. de Belgique, XX. Frey and Leuckart. Beitragen zur Kenntniss der wirbellosen Thiere mit besonderer Berucksichtigung der Fauna des Norddentschen Meeres. Braunschweig, 1847, p..46, Anatomie des Pfahlwurmes (Teredo navalis). Deshayes. Exploration scientifique de lAlgérie, pendant les années 1840, 1841, 1842. Histoire naturelle des Mollusques, avec un Atlas de 117 Planches. Paris, 1847. Ed. Forbes and Hanley. A History of British Mollusca and their Shells. 4 vol. London, 1853. [Contains many anatomical details.] Dalyell, T. G. Rare and remarkable animals of Scotland, represented from living subjects, with practical observations on their nature. Vol. II. London, 1848, p. 138-173, Pl. XXXIV.—XLIIL. (Ascidiae). Lovén. Om utvecklingen af Mollusca acephala, Oversigt af k. Vet. Akad. Forhandl. 5te Argangen, Dec. 1848, Stockholm, 1849, p. 233-257 ; or, its translation in Madler’s Arch. 1848, p. 531; or, in Wiegmann’s Arch. 1849, p. 312. es Quatrefages. Mémoire sur le Genre Taret (Teredo Lin.), in the Ann. d. Sc. Nat. XI. 1849, p. 19. Mémoire sur 'embryogénie des Tarets. Ibid. p. 102. T. Rupert Jones. Cyclop. Anat. and Physiol. IV. p. 1185, Art. Tuni- cata. ; G. A. F. Keber. Beitrage zur Anatomie und Physiologie der Weich- theire, Kénigsberg, 1851. [Devoted to the nervous, circulatory, and res- piratory systems of the fresh-water Bivalvia.] — Ep. CHAPTER I. CUTANEOUS SYSTEM. § 171. The body of the Acephala is enveloped ina special mantle, which, with the Tunicata, is composed of a leathery, cartilaginous, or gelatinous substance, scarcely at all irritable. But with the Lamellibranchia, and Brachiopoda, it is composed of a contractile, fleshy membrane. With the Tunicata, it com- 1 The maritle is leathery with Cynthia. cartilagi- soft with Salpa, and gelatinous with Clavelina, Di uous and hard with Phallusia, cartilaginous and azona, Aplidium, Botryllus, and Pyrosoma. 188 THE ACEPHALA. § 172. ‘pletely surrounds the body and has only an oral and anal opening; ® and with the compound species, it is continuous with the common substance which contains the individuals and binds them into more or less regular groups, and is, therefore, analogous to.a corallum, With the Lamellibranchia, and Brachiopoda, it is more or less open, or even maybe wholly divided into halves; © it has here the property, especially upon its borders, of secreting calcareous matter for the formation of the shell. § 172. With the Tunicata, the mantle is remarkable both for its histological structure, and its chemical composition. Recent investigations have shown ‘that, with the Ascidiae and Salpinae, it is composed of Cellulose and there- fore of a non-azotized substance.” Its anatomical structure is quite complicated. ‘Usually it can easily be separated into two or three layers, the internal one of which is composed, in some species, of a lamellated epithelium formed of a single layer of poly- gonal nucleated cells. Its principal mass in both the compound:and simple forms of this order, is formed of a single, or a double confluent layer of .a homogeneous trans- parent substance, through which are scattered granules, nuclei, groups of pigment molecules, cells, fibres, and crystals of carbonate of lime, — all varying according to genera and species, and often differently arranged in one and the same species. ranged in the inner portion of this 2 These openings are properly only simple ori- fices of the cavity of the body, and correspond to the respiratory tubes of certain Lamellibranchia ; see below, § 190. 3 With Mya, Panopaea, Pholas, Teredo, As- pergilium, the mantle is almost entirely closed, but it has two long fissures ‘at each extrem- ity with Solen, Cyclas, Tellina, Mytilus, Litho- domus and others; with the Ostracea, Pectinea, Arcacea, Naiades, and Brachiopoda, it is entirely open. 1 This important fact was first stated by Carl Schmidt (Zur. vergleich. Physiol. d. wirbellosen Thiere. 1845, p. 61), with Cynthia mamillaris, and has subsequently been confirmed by Lowig and Kélliker, after the must careful investigations upon the entire order of Tunicata (Compt. rend. 1846, p. 38). These two authors found this non- azotized substance, particularly in the different spe- cies of Phallusia, Cynthia, Clavelina, Diazona, Botryllus, Didemnum, Aplidium, Salpa, and Py- rosoma; but not with the other Mollusca, nor with the Annelides, the Helminthes, the Echino- dermata, the Acalephae, and the Polypi. It is certainly wanting in the true Infusoria, for Frus- tulia salina, which Carl Schmidt cites as be- longing to this order and as containing cellulose, is evidently a vegetable. Lowig and Koélliker justly fear, moreover, that this discovery will be quickly seized by those who deny that there.is any limit between the animal and vegetable kingdom (see loc. cit. p. 8). They seek, therefore, to oppose this view by insisting upon the circumstance that this cellulose is never found in a pure state in the mantle of the Tunicata, but always combined with other substances, and that, mereover, no animal has as yet been found entirely composed of this substance. 2 Phallusia mamillarzs, sulcata, Cynthia papil- lata, pomaria, and Salpa bicaudata. But in each species, they are variously ar- mantle-substance.” In some species h and 8 This b: it sul is Ng ) has the same chemical properties as cellulose. 4 Kolliker has made very detailed investiga- tions upon the structure of this mantle. He has kindly allowed me to communicate his results, and authorized me to make use of them without waiting for the publication of his work in common with ‘Léwig (Ueber das Vorkommen von Holzfaser im Thierreich), According to them, the middle layer of the mantle of Phallusia monachus, and sul- -eata, Clavelina lepadiformis, and