20 LICE AND THEIR MENACE TO MAN 



here. A short vagina leads to the exterior from 

 the oviduct. 



The internal male organs consist of a pair of 

 testes, each of which is in two parts. Each testis 

 is connected by a fine tube with a wide seminal 

 vesicle which meets its fellow at the base, where 

 the two pass off into a narrowing duct which 

 carries the male elements to the penis and so 

 into the female during coitus. 



The remainder of the body space is filled up 

 by the muscles and the cells of the fat body. 

 The latter is highly developed and serves to store 

 the food among other functions ; but the detailed 

 physiology of insects is not well known, and it 

 would be useless here to describe special cells 

 and attempt to ascribe to them functions largely 

 hypothetical. 



