THE GENERATIVE ORGANS. 



In the egg-laying female, the uterus often contains an egg in 

 which the embryo is in an advanced stage of development. In 

 Sarcophaga and Tachina it is developed into a large cavity, 

 which is rolled spirally on itself, and contains a large number 



l-'i<;. 95. A median vertical scciion of the uterus of a mature I'low-lly. /, cuticular 

 pad of the genital fn-sa ; ,:, r , genital spine; od, oviduct; /, duct of the par- 

 ovarium ; r J, duct of the rcceptaculum seminis ; r s, receptaculum scminis ; 

 s, sacculus ; //, uterus ; 7; vaginal tube. 



of eggs which are hatched within its cavity, so that these 

 insects (!(})< isit living larvjc. In the pupiparje, the uterus is 

 also largely devc loped, :md contains but one embryo at a time, 

 which grows and develops until it is ready to become a pupa. 



