12G THE HELMINTHES. •§> 117. 



cells ; in the anterior portion, these cells are more numerous and begin to 

 be surrounded by a granular vitelline substance, in which the primitive 

 nucleated cells are still seen; these cells therefore, ought perhaps to be 

 regarded as gerniinative vesicles. In front, these eggs, which are of a dis- 

 coidal form, are arranged in a row, or are grouped closely around a rachis 

 which traverses the axis of the ovary. In the Fallopian tube, which may 

 be known by its less diameter, the eggs become more mature, and, having 

 been surrounded by a double colorless envelope, pass into the base of the 

 uterus.'-' This last is the largest portion of the genital tube, and is dis- 

 tinguished by its well-marked power of peristaltic action. The vagina, 

 which is distinguished from the uterus by its narrowness and its muscular 

 walls, opens at very different points of the body. Generally, as for 

 instance in Ascaris, Spiroptera, Strongylus, Oxyuris, CucuUanus, and Tri- 

 chocephalus, the Vuhm, consisting of a transverse fissure, and often sur- 

 rounded by a very remarkable fleshy swelling, is situated either a little in 

 front of, or near the middle of the body ; but sometimes it opens just in front 

 of the anus.'"* The sperm is usually so accumulated in the bottom of the 

 uterus, that this is probably the locality of fecundation.'^' 



In the males, the posterior portion of this tube is the testicle ; another 

 portion of it, which is short and constricted, is the Vas deferens, which 

 passes into a dilated portion, — i\\QVesicula scminalis. Usually this last is 

 separated by a constriction from the Ductus ejaculatorius, which opens into 

 another muscular tube (sheath of the penis). <■"' At the anterior portion of 

 this last, is a horny, copulatory apparatus. The simple or double penis is 

 of variable length, and is protruded by the muscular contractions of its 

 sheath through the external opening, which is always situated at the poste- 



2 The formation of eggs in various Nematodes borders of the vulva appear quite swollen. With 



has been described by Hiebold {Hurdacli's Phys- Trichosoma, this swelling is so attached to the 



iol. loc. cit. p. 203), by Ba^ge (Dissert, de. Stron- vulva as to resemble a prolapsus of the vagina 



gylo, &c., fig. 1-5), and KbUiker (Mutter's Arch. (Diijardin, Hist. d. Helm. PI. I.). 



1843, p. 63, Tuf. VI. fig. 20). I have found a Witli Filaria attenuata, injiexo-caudata, mihi 



rachis in the ovaries of Ascaris aucta, tumbri- (from the pulmonary cysts of Detphinus pho- 



coides, mi/stax, oscalata, Cucutlanus etegans, caena), and papillosa (see Lcbtond, Quelques 



and Strongytus irtjlexus. The eggs of these, materiaux pour servir & I'histoire des Filaires et 



while yet immature and flattened, have a point on des Slrougles, 1S36, PI. II. fig. 1), the vulva is at 



one of their extremities by which they are attached the side of the mouth, 



to the rachis. With Strongytus paradoxus, it is swollen to the 



With those of Ascaris lumbricoides, this point form of a bladder, and is situated near the caudal 



is very long during a certain period of develop- extremity; while that of Ascaris paucipara is 



ment, and the opposite end has many deep sulca- directly upon the anus. 



tions, giving it a remarkal)le appearance ; see -4 See Basge, loc. cit. p. 12 ; and Kiilliker, in 



Henle, in Mutter's Arch. 1835, p. 602, Taf. XIV. Mutter's Arch. 1843, p. 72. 



fig. 11. 5 For the male genital tube, see Mayer, Beitr. 



In the mature eggs, which are nearly always oval. Tat I., and Ctoquet, Anat. &c. PI. I. tig. 5, PI. 



it is rare that the double colorless envelope can be II. fig. 8. As yet I have observed only a few 



clearly perceived. With Trichosoma, and Tri- exceptions to this tyiiical form with male Nema- 



chocephatus, there is a short diverticulum at each todes. 



extremity of the egg. But in Ascaris dentata. With Filaria attenuata, the posterior portion 



tliere is at this same i)lace a long flbrillated filament; of the testicle is bifurcate, and with Ascaris vesi- 



see Ma^er, ISeitr. Taf. II. fig. 8, and A'o/Zi^er, cMter/.t, there are two moderately large caecal pro- 



in Mutter's Arch. 1843, Taf. VI. fig. 16-19.* longatiuns which arise from the Vesicuta semi- 



'•i W-ith Ascaris dactyturis, Cucuttanus ele- natis at the place where it empties into the Kas 



gans, SIrongytus nodutaris, and striatus, the deferens. 



* [§ 117, note 2.] Primitively, the ova of J sco- become developed into cells, and in this way the 



ris consist of nucleolated cells, which are polyhe- mature ova are formed. Probably no better op- 



dral from mutual pressure. These increase in size portunity is afforded to perceive that morphologi- 



gnuiually, in their passage down towards the ovi- cally the ovum is at first only a nucleolated or 



duct, and the granules of the liquid lying between nucleated cell ; see Leidy, loc. cit. p. 43, PI. VII. 



the nucleus or germiaative vesicle and the cell-wall fig. 14, c. — Ed. 



