676 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 
Ly 
iy 
Fic. 95.—A median vertical section of the uterus of a mature Blow-fly. /, cuticular 
pad of the genital fossa; g, genital spine; od, oviduct; ~, duct of the par- 
ovarium ; xd, duct of the receptaculum seminis; 7s, receptaculum seminis ; 
s, sacculus ; #, uterus ; v7, vaginal tube. 
of eggs which are hatched within its cavity, so that these 
insects deposit living larve. In the pupipare, the uterus is 
also largely developed, and contains but one embryo at a time, 
which grows and develops until it is ready to become a pupa. 
