REPRODUCTIVE SYSTEM; 59 



1. The male organs. 



a. The testes are nine pairs of spherical sacs lying 

 in the somites from the eighth to the sixteenth 

 inclusive. They are situated in the ventral region 

 of the body at the sides of the ventral sinus. 

 Each pair lies mainly in the second, but partly 

 in the first annulus of the somite in which it 



occurs. 



The segmental repetition of the testes is note- 

 worthy. Sometimes a tenth and even an eleventh 

 pair of testes may be present, and occasionally 

 the numbers are unequal on the two sides of the 

 body. 

 Remove- one of the testes, and tease it on a slide in salt 



solution. Cover, and examine with low and high powers. 



Stained preparations can be made by following the directions 



given on page 82. 



Spermatozoa in various stages of develop- 

 ment will be seen. 



b. The vasa efferentia are a series of short sinuous 



ducts which run outwards from the testes, and 

 open into the vasa deferentia. 



c. The vasa deferentia are a pair of longitudinal tubes 



which run forwards in a sinuous course along 

 the ventral body-wall, about midway between the 

 testes and the vesicles of the nephridia. 



In front of the first pair of testes they continue 

 their course through the seventh somite, and in 

 the sixth enter the epididymes. 



d. The epididymes are a pair of convoluted tubular 



bodies with thick white walls lying in the sixth 

 somite. They secrete a substance by which the 

 spermatozoa are aggregated into spermaphores. 

 From the inner side of each a short duct leads 

 to the base of the penis, the duct of the right side 

 passing under the nerve-chain. 



e. The penis is a pyriform body lying in the sixth 



