178 THE ANNELIDES. <^§ 165, 166. 



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.'" 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.*^' 



§ 1G6. 



The disposition of the genital organs of the Hirudinei and Lumbricini, 

 is essentially dift'erent. 



The first have only two simple genital openings, — one male, the other 

 female, both situated, one after the other, u23on the median line of the vcu- 



1 See Duffc.s, Ami. d. So. Nat. XXI. 1830, p. 70, Pulystemma armaturn {Du^es, Ann. d. Se. Nat. 

 PI. II. fig. 5 {Polystemma {Prosturiium) anna- loc. cit. p. 75, PI. II. fi^'. 5) Tetrastemma var'i- 

 tum) ; Johnston, Mag. of Zool. I. p. 532, PI. XVII. color l^Orsted, Ent\7ui-f. &c. p. 23, Taf. III. fig. 

 tig. 2'", 6", Pi. XVIII. fig. 3* (Nemerte.s and 41), and iVejncrfcs (Jo/;n.sion, Mag. of Zool. I. p. 

 Borlania) ; Orsted, Entwurf. einer Beschreib. d. 530, fig. 2 ; ^uo/re/«s-es, Rigneanim. illustr. loc. 

 Plattwiirm. p. 22,. Taf. III. fig. 41 (Tetrastemma cit. PI. XXXI V. fig! 2, and Kolliker, Verhandl. d. 

 varicolor) ; KoUi/cer, Verhandl. d. schweiz. na- sohweiz. &c.) there is at the centre of this organ a 

 turf. Versamml. zu Clnir. p. 91 (jifeniertes); and dart pointing forward*, which is horny, accord- 

 Rathki, Danzig. Schrift. loc. cit. p. 98 (Borlasia ing to Dus'es, and calcareous, according to Orsted. 

 striata). This last author has not seen the orifices Ou each side of this dart, there is a reservoir of 

 of the genital organs. Quatrefages {Kigneaxnm. many others, smaller and yet imperfect, destined , 

 illustr. loc. cit. PI. X.X.XIV. tig. 1, n. n.)' did not probably, to replace the former when lost. Duifes. 

 see them with Nemertes Camilla, and Johnston Johnston, and (^uatrefages, who regard this or- 

 is also silent on this subject. According to Orsted gan as an intestinal canal, and Kolliker, who con- 

 (Entwurf. &c. loo. cit. p. 25, Taf. III. fig. 47, of siders it prehensile, all regard those darts as a kind 

 Notospermus Jlaccidus) the Nemertini secrete of teeth ; but Orsted thinks they serve to excite 

 from the whole surface of their body, a gelatinous the genital organs. For my part, they involunta- 

 mucus, which surrounds the eggs, and thus forms ril.v remind me of the darts of the Helicina. 

 an envelope into which they can draw their bodies. [Additional Note.] — I have now satisfied, myself 

 Something similar to this occurs with the Lumbri- upon living individuals of T'etrastevima, that the 

 cini and Hirudinei. See below. eggs can escape from the visceral cavity through 



!i The Nemertini being of distinct sexes, tliis or- immerous lateral openings in the wall of the body, 



gan can be regarded neither as a penis, nor as an I ara also satisfied that witli the Nemertini, the 



everted spermatic vessel, as Huschke has done walls of the digestive canal (the middle body-cavity 



(Isis, 1830, p. 682, Taf. VII. fig. 5). More prop- according to Quairefages) are not the jjoints of 



erly could it be considered, with Orsted (Entwurf. departure of the genital organs, as Quatre/ages 



&c. p. 25), as an excitatory organ; although Rathki thinks, and who also would regard as a digestive 



(Danzig. Schrift. loc. cit. p. 100, and Nov. Act. Acad, tube the snout of these animals, an organ which is 



Nat. Cur. XX. p. 233) re;;ards it as of a tactile, yet enigmatical. The very detailed figures which 



and Kolliker of a prehensile nature (Verhandl. d. this natui-alist has given (loc. cit.) of the walls of 



schweiz. p. 90). Other oljservers agree with the digestive canal of these animals, present nothing 



Ehrenberg (Symb. phys. loc. cit.) that it is an in- like an ovary, and show no trace of the presence 



testine and an everted ujsophagus, its orifice being of germs, 

 a mouth ; but this is uuiloubtedly erroneous. With 



