^^ 226, 227. 



THE CEPHALOPHORA. 



25T 



§ 226. 



Among all the hermaphrodite Cephulophora, the genus Sagitta stands 

 wholly alone, in having all parts of its genital apparatus double. 



The ovaries consist of two straight, non-ciliated tubes situated at the pos- 

 terior extremity of the cavity of the body ; these open externally by an 

 arcuate oviduct, situated upon the back directly over the median line of 

 each of the posterior lateral fins. 



The two internally ciliated testicles fill the caudal cavity, which is 

 divided into two chambers by a longitudinal septum. They send backwards 

 two short deferent canals, which open in front of the caudal fin, by two tumid 

 orifices, but are without copulatory organs. ^^' 



§ 227. 



As for the other hermaphroditic Cephalophora, to which belong the 

 Pteropoda and a majority of the Gasteropoda, the genital organs of the 

 Nudibranchia, Inferobranchia, Tectibranchia, and Pulmonata, have been 

 the most thoroughly investigated. But the different divisions of these 

 organs have been interpreted in a manner so varied and contradictory, that 

 one can almost despair of having any positive knowledge of their rela- 

 tions.*" 



1 See Krohn, loc. cit. p. 9, fig. 2, 7-9. The cil- 

 iated epithelium which covers the male genital 

 organs oi Sagitta, from the posterior extremity to 

 the genital on flee, produces a general up-and-down 

 movement of the sperm in the testicle, a phenome- 

 non which Darwin has compared to the motions 

 of the sap in Chara (Ann. of Nat. Hist. XIII. p. 

 3, PI. I. tig. 1, or Froriep^s neue Notiz. No. 633, p. 

 3, fig. 62, and Ann. d. Sc. Nat. I. 18i4, p. 362, 

 PI. XV. B). Far the genital organs of Sagitta, 

 see also the researches of fViims (loo. cit. p. 12). 



1 It has been quite diiticult to reconcile the fact 

 that, with these animals, the testicle and the ovary 

 are united in a single body, — the Hermaphrodite 

 gland. Cuvier, whose opinion has been followed 

 by Meckel, and Carus, in theii- üifferent publica 



observed exactly like Kö/liker.. IhAve found these 

 particles throughout this group, generally, to consist 

 of a delicate thread, one end of which is more or less 

 incrassated and twisted in a cork-screw manner 

 {^olis, Physa, Lymnaeus, Natica, Helix, Li- 

 max, &c.) ; in some, however, the form is remarka- 

 bly different. Thus, with Buccinum, it consists of a 

 thread with a terminal third somewhat incrassated, 

 but which terminates in a delicate filament. This, 

 as will be seen above, Kölliker has also noticed. 



As to the remarkable statements made above 

 upon two kinds of spermatic particles with Palu- 

 dina vivipara, they deserve our especial attention. 

 My own investigations have led me to regard it as 

 a law in Spermatology, that each animal had only 

 one kind of spermatic particle, the shape and size of 

 which in that animal, are invariably the same ; this 

 point I have regarded as so well established that 

 I have proposed the basis of an animal classifica- 

 tion from spermatological data. I was therefore 

 surprised to find an observer like Leydig who has 



22* 



tions, regarded this gland, with the Pulmonata. as- 

 an ovary, and the albumen-secreting organ, as a 

 testicle. Treviranus (Zeitsch. fur Physiol. I. 

 p. 3. V. p. 140) was of the opposite opinion ; he 

 considered the hermaphrodite gland as a testi- 

 cle and the other as an ovary. This view ha» 

 been adopted by Prevost ( Mem. d. 1. S;)C. Phys. 

 de Genöve, V. p. 119, and Ann. d. So. Nat. XXX. 

 p. 33, 43), and by Paasch (Diss. loc. cit. and 

 fViegmann's Arch. 1843, I. p. 71, 1845, I. p. 34). 

 In England, Rymer Jones adopts the view of Cu- 

 vier, and Owen that of Treviranus. fVohnlick 

 ( loc. cit. p. 32) names as ovary, the albumen 

 gland 5 and as testicle, the half-canal which runs- 

 al.mg the uterus ; but he is ui doubt as to the 

 function of the hermaphrodite gland. Erdl, who 



recently gone over the ground, according his views 

 with those of Siebold and others above-mentioned 

 (see Beitrag, loc. cit. in Siebold and Kölliker\'i 

 Zeitsch. II. 1850, p. 125, Taf. XIII. fig. 31-43). 

 Leydig, however, has watched their formatioa 

 from cells ; and here I may remark as being evi- 

 dence against their being spermatic particles, that,^ 

 according to him, they are produced by the meta- 

 morphosis of an entire nucleolated cell, and not, as 

 is the grand law with spermatic particles, from a 

 cell-nucleus. From this and from the above-men- 

 tioned reasons, based upon analogy, I cannot ad- 

 mit that these peculiar bodies are true spermatic^ 

 particles. Leydig's observations on their develop- 

 ment of course render invalid the hypothesis of 

 Gratiolet that they are modified spermatic parti- 

 cles, having undergone changes, like those of the 

 Helicina, in the Vesicula copulatrix ; see Jour, de 

 Conchol. No. 11. 1850, p. 116, and No. III. p. 

 230, PI. IX. flg. 3-7. — Ed. 



