146 THE COMMON FROG. [chap. 



urinary gland is what is called the " Wolffian body," 

 which after a time ceases to grow, and ultimately 

 more or less disappears, becoming an appendage to the 

 glandular structure related to the oviduct or to its 

 analogue in the other sex. Thus, though the kidney, 

 with its duct the ureter, never has any direct con- 

 nection with the oviduct or its appendages, neverthe- 

 less, a renal structure, with its excretory duct, has such 

 a connection at one time of life, even in the highest 

 animals. 



In fishes the primitive renal (or urinary) organ per- 

 sists throughout life. It answers rather to the tem- 

 porary Wolffian body than to the true kidney of 

 higher animals. It is also a fact that in some fishes 

 {e.g. Ceratodus and Lepidosireii) a connection does exist 

 between the renal ducts and the oviducts, anterior to 

 the termination of either. 



Now in the frog (and in its class-fellows) this highly 

 important excretory organ presents a noteworthy con- 

 dition. In the adult frogs and toads the renal or 

 urinary gland pours its secretion by minute canals 

 into the renal duct. This duct, however, does not 

 open into the cloaca, as does the ureter of birds and 

 reptiles, but into the oviduct, the oviduct and renal 

 duct of each side thus opening into the cloaca by 

 a single and common aperture. An analogous con- 

 dition exists in the male frog and toad, and in most 

 members of their order. 



In the genera Bombinator and DiseoglosstiSy how- 

 ever, as also in the male Urodela, a still more intimate 

 union exists between the renal organs and those de- 

 voted to functions complementary to oviposition. The 



