Fig. 7. 





Pig. 8. 



Fig. 8. Young transparent egg. 



a. Yolk. 



b. Germinative vesicle. 

 e. Germinative dot. 



Fig. 9. 



SYESKI ON THE OEGANS OF EEPEODUCTION OF FISHES. 723 



In other fishes, the spermatic organs are composed of lobes united by 

 means of vasa deferentia. 



In the male eel, 

 these lobes form two 

 lateral rows (fig. 7), 

 extending nearly 

 the whole length of 

 the abdominal 

 cavity. 



The eggs of fish 

 (like those of other 

 animals) are, in the 

 beginning of their 

 development, of mi- 

 croscopic size, and 

 consist of a trans- 

 parent yolk, which 

 incloses the germi- 

 nal cell (fig. 8). In 

 the state of matur- 

 ity, however, they 

 differ considerably 

 in size, and in some cases, though rarely, in form, as to their contents, 

 and in their covering. The mature eggs of the "pesci-cani" (dog-fish), 



the " tremoli" (Torpedo), &c, which are as large 

 as hen or goose eggs, consist of a yellow yolk in- 

 closed in a membrane, and a germinative disk, 

 measuring about three millimeters in diameter, 

 placed on the surface of the yolk under the 

 membrane, and which contains the germinative 

 cell (fig. 9). From the disk of the fecundated egg 

 is formed the embryo, to which the yolk serves 

 as food. 



When the egg has entered the oviduct, it be- 

 comes covered with a layer of gelatinous matter, 

 and in the a gatte" (Scyllium), "rase" (Raja), 



Fig. 7. Testicles. 



a. Eight testicle. 



b. Left testicle. 



c. Deferent canal. 



d. Intestine. 



e. Seminal pouch. 



/. Part of the abdominal wall 



g. Anns. 



h. Uro-genital orifice. 



i. Urinary bladder. 



Fig. 10. 



Fig. 9. Egg. 



a. Yolk. 



b. Germinative vesicle. 



c. Germinative dot. 



&c.j also with a solid horny case, produced by 

 the glands of the oviduct (fig. 10). 



The mature eggs of osseous fish (fig. 11) are 

 about one to six millimeters in diameter, and 

 sometimes even less than one. When they are 

 half-matured, they are of a yellow or white 



t. Gelatinous matter , , , ., ,-, -, 



surrounding the color ; and when quite mature, they are almost 



yolk in the same 



manner as the white transparent. 



of the egg in birds' _,. „ „ , , ., , .,, . 



eggs. The sperm of fish, commonly called milt, is a 



thick, white liquid, containing innumerable small spermatic bodies, or 



Fig. 10. Egg. 



a. Corner of the shell. 

 6. Horney shell of the 



egg. 

 e. Yolk of the egg or 



nutrive yolk. 

 d. Germinative disk, or 



yolk of evolution. 



