The Development of the Frog 85 



" A little later, after completion of metamorphosis and 

 the entire disappearance of the tail, this anterior end of 

 the segmental duct, in front of the Wolffian body, be- 

 comes divided somewhat obliquely into two ; an anterior 

 part, which is now isolated from the Wolffian body, and 

 will be called the Mullerian duct ; and a posterior part, 

 the Wolffian duct y which is simply the posterior part of 

 the original segmental duct, and receives the Wolffian 

 tubules of the kidney. 



" The Mullerian duct becomes connected in front with 

 the peritoneal epithelium, and acquires an opening into 

 the anterior end of the body-cavity. At its hinder end 

 it grows back along the outer side of the Wolffian duct 

 to the cloaca, into which it opens. So far the changes 

 are the same in both sexes. In the male frog the Mul- 

 lerian duct persists in this condition throughout life, and 

 may be recognized as a slender, longitudinal streak lying 

 in the thickness of the peritoneum a short distance to the 

 outer side of the kidney, and extending some distance in 

 front of it. In the female frog the Mullerian duct be- 

 comes the widuct, 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 ; while the posterior part 

 becomes greatly convoluted and acquires thick glandular 

 walls ; the hindermost part of the oviduct remains thin- 

 ner walled, but of much greater capacity. 



" The Wolffian 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 vesicula seminalis. 



