148 DEVELOPMENT OF THE FKOG 



outer side of the kidney, and extending some distance in front 

 of it. In the female frog the Miillerian duct becomes the 

 oviduct, the anterior opening being carried forward first as a 

 groove, and then by closure of the lips as a tube, to the position 

 characteristic of the peritoneal opening of the adult oviduct ; 

 whUe the posterior part becomes greatly convoluted and acquires 

 tliiok glandular walls : the hindmost part of the oviduct remains 

 thinner walled, but of much greater capacity. 



The WoMan duct becomes in both sexes the ureter. In 

 the female frog it undergoes no further change of importance. 

 In the male frog the hinder end of the Wolffian duct becomes 

 dilated into a much-branched glandular enlargement, the 

 vesicnla seminalis. 



5. The Vasa Efferentia. 



In both sexes at an early stage, as the Malpighian bodies 

 are forming in the Wolffian body, those nearest to the genital 

 ridges give off tubular branches from their capsules into the 

 ridges. 



In the female frog these tubules are said to expand very 

 greatly, and to give rise to the chambers or cavities present 

 in the adult ovary : but the point is not established with 

 certainty. 



In the male frog these tubules become the vasa efferentia : 

 they become connected with the spermatic tubules, and, as at 

 their other ends they open into the Wolffian tubules, they form 

 passages along which the spermatozoa can get from the testis 

 to the Wolffian duct or ureter, and so out. 



