350 PHILOSOPHY OF ZOOLOGY. 



In the males of this division, the testes, known by the 

 name of milts, are two in number, of a white colour, and 

 lengthened form. The surface is usually irregularly tuber- 

 culated. They are situate on each side of the abdomen, 

 and consist of gland ulous sacs destined for the preparation 

 of the impregnating fluid. Through the middle of each 

 milt there passes a ductus deferens, uniting with each other 

 at the posterior part of the abdomen, and forming a kind of 

 vesicula seminalis. This duct either terminates in the cloa- 

 ca, or by a small orifice near its caudal margin. 



We possess few accurate experiments on the chemical 

 composition of the seminal fluid of fishes. FOURCROY pub- 

 lished * some experiments on the milt of the carp. He 

 found that it was neither acid nor alkaline. It appears to 

 consist of albumen, gelatine, phosphorus, phosphat of lime, 

 phosphat of magnesia, and muriat of ammonia. More re- 

 cently, Dr JOHN subjected the milt of a tench to a chemi- 

 cal analysis, and obtained the following ingredients : water, 

 insoluble albumen, gelatine, phosphat of ammonia, phos- 

 phat of lime, phosphat of magnesia, and alkaline phosphat. 

 He could not detect the presence of any phosphorus, which 

 had been given as a constituent by FOURCROY and VAU- 

 QUELIN. In all these examples, however, the seminal fluid 

 was mixed with the substance of the testes. 



In \hejemales of this division, the ovary, usually termed 

 the roe, is double in the greater number of fishes, but in a 

 few it appears to be single. It occupies nearly the same po- 

 sition as the milt in the males. It consists of a thin delicate 

 folded membrane inclosing the ova, disposed in transverse 

 layers, and connected by means of bloodvessels. There is no 

 distinct oviduct. The external openings are similar to those 

 in the male. 



* Annales de Chim. vol. Ixiv. p. 3. 



