AMPHIBIA 



223 



mesonephric tubules lose their communications with the 

 splanchnocoel. The nephrostomal part of the tubule in each 

 case is cut off from the Malpighian body, which thus becomes 

 terminal, and it establishes an opening into a factor of the 

 renal veins. 



The gonads appear as ridge-like thickenings of the peri- 

 toneum medial to the mesonephros. In the male the ducts 

 of the testis on each side are connected with the anterior 

 Malpighian bodies into which they open. The mesonephric 

 duct of the male thus is also a gonoduct. The kidney is the 

 Wolffian body, and its duct the Wolffian duct. In the females 

 the ovaries are not so connected, and the mesonephric duct 



Conad 



Gonad 



FIG. 112. Transverse sections illustrating two stages in the development 

 of the mesonephric tubule. 



functions only as a ureter. The oviduct, or Mullerian duct, 

 is like that of the Elasmobranch, and it opens anteriorly into 

 the body cavity. It has been said to be developed by a 

 splitting of the pronephric duct as in the Elasmobranch, but 

 most observers state it is developed independently from a 

 groove which forms in the peritoneum. The bladder is 

 developed as a ventral outgrowth of the cloaca. 



In the adult frog the kidneys lie one on each side of the 

 vertebral column in the abdominal lymph space. They are 

 elongated red bodies and are traversed ventrally by the 

 yellowish adrenal. The tubes of the kidney filter water from 

 the blood at their commencement in Bowman's capsules. 

 The arteries entering the kidney give rise to a multitude of 

 glomeruli, and the efferent vessels run into sinusoids, where 

 they are joined by the branches of the renal portal. Both 

 these, therefore, contribute to the capillaries which surround 



