RENAL AND, EEPRODUCTIVB SYSTEMS. 



255 



median aperture, and become converted into the oviducts ; 

 the Wolffian body is small and unimportant ; while the 

 metanephros and its ducts form the functional kidney and 

 ureters of the adult. 



In the male the Miillerian ducts are abortive and function- 

 less ; the mesonephric tubules become connected with the 

 testis, and act as vasa efferentia, conveying the spermatozoa 

 to the mesonephric or WolfQan duct which acts as vas deferens. 

 The metanephros and metanephric ducts, as in the female, 

 become the functional kidney and ureters. The tubules of 

 the kidney have persistent nephrostomes opening into the 

 body-cavity. 



TABLE SHOWING THE EMBRYONIC AND ADULT CONDITIONS OF THE IvIDNET! 

 AND THEIR DUCTS. 



A. The Female. 



1. The ovary, which is single, is an elongated soft lobu- 



lated mass, varying a good deal in size, but usually 

 about two or three inches long in specimens of the 

 size described. It lies in the abdominal cavity a little 

 to the right of the median plane, and is attached to 

 the dorsal wall by a narrow fold of peritoneum, which 

 is very easily torn. The ova form conspicuous 

 rounded projections on the surface of the ovary, and 

 when fully formed are half an inch or more in 

 diameter. 



2. The oviducts, which are formed from the Miillerian 



ducts of the embryo, are a pair of tubes running 



