§164. 



TUE ANNELIDES. 



177 



vitellus is usually whitish or yellowish, but rarely of a more marked 

 color/'" 



With the Hirudinei and Lurabricini, the spermatic particles are filaraen- 

 toid and very active, while with the other Annelides they have the form of 

 Cercariae.^''^ 



§ 164. 



^Yith the Hirudinei, and Lumbricini, the two sexes are always united in 

 the yame individual. The sexual organs consist of testicles, vasa deferen- 

 tia, and vesiculae seminales ; then, ovaries, oviducts, and the male and 

 female copulatory organs. The female copulatory organs are upon the 

 ventral surface of the anterior part of the body and behind the male 

 organs — so that two individuals by placing together their anterior ventral 

 surfaces in an inverse position, can be mutually impregnated.'^' 



The excretory ducts of both sexes are often lined with a very delicate 

 ciliated epithelium. 



from the eggs of other Annelides, in containing be- 

 tween the vitellus and vitelline membrane a layer 

 of caudate ceUs. These cells, of variable number 

 and size, but always of uniform size in the same 

 egg, have often been compared, from their form, to 

 Naviculacae ; see Henle, in MiiUer^s Arch. 1S35, 

 p. 591, note, and Hojfmeister, De vermibus qui- 

 busdam, &c., Tab. II. fig. 14-17. 



3 The vitellus is rose-colored, or greenish, with 

 Clepsine, and violet with Polynoe. 



4 The development of the spermatic particles of 

 the Hirudinei and Lumbricini is very remarkable. 

 The cell-racmbrane of the parent cells, in which the 

 spermatic particles are usually developed, disap- 

 pears before these last are developed. There are then 

 small cells groui)ed around a discoid nucleus. These 

 cells lengthen out, and finally become spermatic 

 particles, and they remain attached to the disc until 

 fully developed. If a bundle of these is placed 

 in water, they separate and become intertwisted in 

 the usual manner ; see Henlc, in Muller''s Arch. 

 1835, p. 584, Taf. XIV. fig. 4, 6, 7, 9 ; Kolli/cer, 

 Beitr. zur Kenntn. d. Geschlecl its verbal tnisse, p. 

 17, Taf. II. fig. 16, 18, 19 ; H. Meckel, Muller's 

 Arch. 1844, p. 477, Taf. XIII. fig. 2-10 (Sangui- 

 suga, Pontobdella, and Branchiobdella) ; and 

 Hojfmeister, De vermibus quihusdam, &c.. Tab. 

 II. fig. 6-10. From Stannius' description and fig- 

 ures of the sperm of Arenicola (Mtil/er^s Arch. 

 1840, p. 375, Taf. XI. fig. 3-6); and Rathki of that 

 of Amphitrite auricoma (Danzig. Schrift. loc. cit. 

 p. 67, Taf. V. fig. 13) ; and quatrefages, of that 

 oiNemertcs mandilla (Regneanim. illustr. Zooph. 

 PI. XXXIV. fig. 3-5), we can conclude that the 

 spermatic pai'ticles of the other Annelides are de- 



* ( § 163, note 4.] For the spermatic particles 

 of the Hermella, see Quatrefages (Ann. d. Sc. 

 Nat. X. 1S48, p. 167) ; he describes them as being of 

 a cercaria-form. My own results on the spermatic 

 particles of the Annelides and their development, 

 do not agree with the view above expressed. Here, 

 as elsewhere, I have found them to be the metamor- 

 phosed nucleus of the daughter-cells. It is true 

 that with the Lumbricini they present some pecu- 

 liarities, but these are apparent only. The mul- 

 berry-like mass to which they are here found ad- 

 herent, is composed of the remains of the develop- 

 ment, and the spermatic particles which seem to ra- 

 diate from it in all directions present this appear- 



veloped like those of the Hirudinei and Lumbricini. 

 While in the excretory ducts of the sperm, tlie 

 spermatic particles are found in bundles ; and when, 

 as at the procreative period, many of these Ijundles 

 are collected together, their very active, undula- 

 tory movements give a most wonderful appearance 

 beneath the microscope ; see Morren, loc. cit. p. 

 178, Tab. XXIV.-XXVIII., and myself in MiiUer's 

 Arch. 1836, p. 42. Among the fllamentoid sperm- 

 atic particles of Hirudinei, those of Branchiob- 

 della are worthy of special mention. One of their 

 extremities is delicate and spu'ally turned (see my 

 observations, Miiller^s Arch. 1836, p. 42, Taf. II. 

 fig. 8), and terminates, according to Kolliker, by a 

 small vesicle (loc. cit. p. 18, Taf. II. fig. 16, f.). 

 With the Branchiati, the cercarian-form predomi- 

 nates, according to Quatrefages (Comp. Rend. 

 XVII. 1843, p. 424). With the Neraertini, tliey are 

 either simply fllamentoid (Notospermus, accord- 

 ing to Orsted, Eatwnrf. einer Emth. d. Plattwiirra. 

 loc. cit. Taf. III. fig. 54) or more cercarian-form 

 (Nemertes, according to Quatrefages, Kegne 

 anira. illustr. Zooph. PI. XXXIV. fig. 6 ; and Kdl- 

 liker, Verhandl. d. schweiz. naturf. Gesellsch. bei 

 iiirer Versammlung zu Chur. 1844, p. 91). 



For the spermatic particles of the Annelides, see 

 especiallv Kiilliker in the Neue schweiz. Denkschr. 

 VIII. p. 33.* 



" See Bojanus, Isis, 1818, Taf. XXVI. fig. 1 ; 

 Brandt, Med. Zool. II. Taf. XXX. fig. 25 (Sangui- 

 suga wedicinalin) ; Leo, jyiiiller'.i Arch. 1835, 

 Taf. XI. fig. 3 (Piscicola seometra) ; Morren, 

 loc. cit. Tab. XXVII.-XXXI.; and Hojmeinter, 

 De vermibus quibusdam, &c.. Tab. I. iig. 29, 30 

 (Lumbricus and Enchytraeus).\ 



ance because they are then just escaping from the 

 daughter-cells, and the more or less adherence of 

 the membrane of these last to the particles, gives 

 the appearances above mentioned in the note. I 

 have observed the same appearances with some of 

 the Coleopterous insects, where the development 

 occurs unmistakalily in special cells. These par- 

 ticles are, according to my own observation, liaU- 

 like with the Hirudinei, and Lumbricini, but are 

 pin-shaped with some of the Capitibranchiati. — Ed. 

 t [ § 164, note 1.] See also Leydig, Sicbol «/a!uI 

 Kiilliker's Zeitsch. HI. lift. 3, p. 318, and quatre- 

 fages, Ann. d. Sc. Nat. XVIII. 1852, p. 299 

 (Branch el/ion). — Ed . 



