Comparative anatomy / by C.Th. v. Siebold and H. Stannius ; translated from the German, and edited with notes and additions recording the recent progress of the science by Waldo I. Burnett.

  • Karl Theodor Ernst von Siebold
Date:
1854
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Licence: Public Domain Mark

Credit: Comparative anatomy / by C.Th. v. Siebold and H. Stannius ; translated from the German, and edited with notes and additions recording the recent progress of the science by Waldo I. Burnett. Source: Wellcome Collection.

Provider: This material has been provided by The University of Glasgow Library. The original may be consulted at The University of Glasgow Library.

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    bricini at this period, is of an analogous nature. It is also composed of numerous cutaneous glands, closely aggregated, and extending completely over many segments of the body.<4) 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 can 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 tilled throughout.® It is possible that the scarcely visible orifices said to be concealed be- 4 Saenuris, Nais, &c.j see Gruithuisen, loc. cit. Tab. XXXV. fig. 5, b.b. 0 With the large species of Lumbricus, each co- coon has from one to six eggs (L. Dufour, Ann. d. Sc. Nat. XIV. 182S, p. 216, PI. XII. B. or, Froriep's Notiz. No. 472,1828, p. 149, fig. 13-16 ; and Hojf- meister, De vermibus quibusdam, Tab. I. and Die Arten aus der Familie, &c., p. 16, 25, 42). With the smaller Lumbricini, as with Saenuris, Euaxes, Nais, &c., the cocoons contain nearly always five to eight eggs (Dugas, loc. cit. XV. PI. VII. fig. 5, Nais). Most of these cocoons have appendages by which they are attached to vegetables and other bodies. Hojfmeister (Die Arten aus der Fam. &c. 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) ; Rathka, De Bopyro et Nereide, p. 39, Tab. II. fig. 12, 1. (Nereis), and Danzig. Schrift. loc. cit. p. 66, Taf. V. fig. 6, hh. fig. 11, aa. (Amphitrite) ; Grube, Zur Anat. d. Kiemenwfirmer, p. 16, Taf. I. fig. 1, 2, m. (Arenicola), p. 44, Taf. II. fig. 6, y. z. (Eu- nice); also, Nov. Act. Acad. XX. p. 201, Tab. X. fig. 13, 15, m. (Ammo try pane). Rathke's and Grubers 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 Rathke and Grube, are * [§168, note 2.] According to Quatrefagcs (Ann. d. Sc. Nat. X. 1848, p. 46) the sexes are sep- arate with the Hermella. 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 tern- 16 of the opinion 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 : Terebella, Sabella, Aricinella, Nephtys, Syllis, Glycera, Eunice, Sigalion, Phyllodoce, Nereis, and Aphrodite ; see Comp. Rend. XVII. 1843, p. 423. But before this, Stannius had concluded that the sexes were separate with Arenicola, from a difference in the contents of the cavity of the bodies of different in- dividuals (Muller''s Arch. 1840, p. 375). The glands at the cephalic extremity of the Branchiati which live incases,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.) * 3 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 (Muller's Arch. 1840, loc. cit.). Ac- cording to Krohn (IViegmann's Arch. 1845, I. p. 182), the eggs and the spermatic particles, with Al- 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, Arnmotry- pane, Ephesia, Hermella, Perm ilia, Fabricia, and Spirorbis ; they speak of the presence of ova- ries and testicles in certain Annelides (Aphrodite, Arenicola) 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. — Ed.