RENAL AND REPRODUCTIVE SYSTEMS. 267 



it : the rectum in front, the genital aperture in the 

 middle, and the urinary sinus behind. 



B. The Male. 



1. The testes are a pair of soft elongated bodies lying along 



the dorsal wall of the abdominal cavity, and in the 

 adult united with each other at their hinder ends. 

 Like the ovary, they are attached to the body-wall 

 by delicate folds of peritoneum which are very 

 easily torn, so that in many specimens the testes 

 appear to lie free in the abdominal cavity. 



2. The vasa efferentia are a number of very slender ducts 



which arise on each side from the dorsal surface of 

 the testis, and run forwards in the fold of peritoneum 

 to the Wolffian body, which they enter at its anterior 

 end. 



3. The kidneys. Each kidney is, as in the female, divided 



into an anterior part and a posterior excretory 

 part. The anterior half differs from that of the 

 female in being secondarily connected with the 

 reproductive system forming the epididymis or 

 genital portion. The hinder part, as in the female, 

 is a laterally compressed mass of considerable size, 

 especially thick at its hinder end. This part is the 

 functional kidney. 



Dissect off the 'peritoneum from the ventral surface of one 

 of the kidneys, so as to expose it along its whole length. At 

 the hinder end dissect the kidney from the body-wall along its 

 outer side t so as to see its full size. 



4. The Wolffian ducts are a pair of thick-walled tubes 



running in a very sinuous course along the ventral 

 surface of the genital portion oi the kidney, from 

 which the ducts receive numerous segmentally 

 arranged tubules. Opposite the junction of the two 

 portions of the kidney they dilate rather suddenly 

 into two wide thin-walled tubes, the vesiculae 



