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. 

 TK^ 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 tha 

 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 veu- 



1 See Du^is, Ann. d. Sc. Nät. XXT. 18S0, p. 76, 

 PI. Tl. fig. 5 (Polystemma (Prostomum) arma- 

 tum) ; Johnston, Mag. of Zool. I. p. 5.32, PI. XVII. 

 fig. 2", 6",. Pi. XVIII. fig. 3* (Nemertes and 

 Bor/asia) ; Orsted, Entwurf, einer Beschreib, d. 

 Plattwürm. p. 22, Taf. III. fig. 41 (Tetrastemma 

 varicolor) ; KöUiker, Verhandl. d. Schweiz, na- 

 turf. Versamml. zu Chur. p. 91 (Nemerten); and 

 Rathki, Danzig. Schrift, loo. cit. p. 98 (Bor/asia 

 striata). Tliis last author has not seen the orifices 

 of the genitiil organs. Quatrefai^es (Regne anim. 

 illustr. loo. cit. PI. XXXIV. tig. 1, n. n.) did not 

 see them with Nemertes Camilla, and Johnston 

 is also silent on this sulyect. Acordiag to Örsted 

 (Entwurf, kc. loc. cit. p. 25, Taf. III. fig. 47, of 

 Nolospermus 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 di'aw their bodies. 

 Something similar to this occurs with the Lumbri- 

 cini and Ilirudiiiei. See below. 



2 The Ni-mertini being of distinct sexes, this or- 

 gan can be regarded neither as a penis, nor as an 

 everted spirmatic vessel, as Huschke has done 

 (Isis, 1830, p. 682, Taf. VII. fig. 5). More prop- 

 erly could it be considered, witti Örsted (Entwurf. 

 kc. p. 25), as an excitatory organ; althtjugh Rathki 

 (Danzig. Schrift, loc. cit. p. 100, and Nov. Act. Acad. 

 Nat. Cur. X.K. p. 233) regards it as of a tactile, 

 and KöUiker of a prehensile nature (Verhandl. d. 

 Schweiz, p. 90). Other observers agree with 

 Khrenber^ (Syinb. pliys. loc. cit.) that it is iin in- 

 testine and an everted (usojjhagus, its orifice being 

 a mouth ; but this is undoubtedly erroneous. With 



Polystemma armatum (JOu^es, Ann. d. Sc. Nat. 

 loc. cit. p. 75, PI. II. fig. 5) Tetrastemma vari- 

 color {Örsted, Entwurf, kc. p. 23, Taf. III. fig. 

 41), and Nemertes {Johnston, Mag. of Zool. I. p. 

 530, fig. 2 ; Qiiatrefa^es, R^gne anim. illustr. loc. 

 cit. PI. XXXIV. fig. 2, and KöUiker, Verhandl. d. 

 Schweiz. &c.) there is at the centre of this organ a 

 dart pointing forward", which is horny, accord- 

 ing to Dugis, and calcareous, according to Örsted. 

 On each side of this dart, there is a reservoir of 

 many others, smaller and yet imperfect, destined, 

 liroliabjy, to replace the former when lost. Duges, 

 Johnston, and Quatre/ases, who regard this or- 

 gan as an intestinal canal, and KöUiker, who con- 

 siders it prehensile, all regard these darts as a kind 

 of teeth ; but Örsted thinks they serve to excite 

 the genital organs. For my part, they involunta- 

 rily remind me of the darts of the Helicina. 



[Additinnal 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 (^uatrefages) are not the points of 

 departure of the genital organs, as Quatre/ages 

 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 tlie preSeuce 

 of germs. 



