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
Catalogue details

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.

    182/482 (page 178)
    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. The 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.(1) 2 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 tire 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 Dupes, Aim. d. Sc. Nat. XXI. 1830, p. 76, PI. II. fig. 5 (Polystemma (Prostomum) arma- tum) ; Johnston, Mag. of Zool. I. p. 532, PI. XVII. fig. 2'*, 6*% Pi. XVIII. fig. 3* {Nemertes and liorlasia) ; Orsted, Entwurf. einer Beschreib. d. Plattwiinn. p. 22, Taf. III. fig. 41 (Tetrastemma varicolor) -y Kolliker, Verhandl. d. Schweiz, na- lurf. Versamml. zu Chur. p. 91 {Nemertes)-, and Rathkd, Danzig. Schrift. loc. cit. p. 98 (Borlasia striata). This last author lias not seen the orifices of the genital organs. Quatrefages (R££ne anim. illustr. loc. cit. PI. XXXIV. fig. 1, n. n.) did not see them with Nemertes Camilla, and Johnston is also silent on this subject. According to Orsted (Entwurf. kc. loc. cit. p. 25, Taf. III. fig. 47, of Notospermus Jlaccidus) 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 Ilirudinei. 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 (Isis, 1830, p. 682, Taf. \ II. fig. 5). More prop- erly could it be considered, with Orsted (Entwurf. kc. p. 25), as an excitatory organ-, although RathlU (Danzig. Schrift. loc. cit. p. 100, and Nov. Act. Acad. Nat. Cur. XX. p. 233) regards it as of a tactile, and Kolliker of a prehensile nature (Verhandl. d. schweiz. p. 90). Other observers agree with Ehrenberg (Symb. phys. loc. cit.) that it is an in- testine and an everted oesophagus, its orifice being a mouth ; but this is undoubtedly erroneous. With Poti/slcmma armatum {Dupes, Ann. d. Sc. Nat. loc. cit. p. 75, PI. H. fig. 5) Tetrastemma vari- coior {Orsted, Entwurf. &c. p. 23, Taf. III. fig. 41), and Nemertes {Johnston, Mag. of Zool. I. p. 530, fig. 2 Quatrefages, Iiegne anim. illustr. loc. cit. PI. XXXIV. fig. 2, and Kolliker, Verhandl. d. schweiz. kc.) there is at the centre of this organ a dart pointing forward*, which is homy, accord- ing to Dupes, 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. Dupes. Johnston, and Quatrefages, who regard this or- gan as an intestinal canal, and Kolliker, who con- siders it prehensile, all regard these darts as a kind of teeth 5 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 Tetrastemma, that the eggs can escape from the visceral cavity through numerous lateral openings in the wall of the body. I am 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.