THE DUCTLESS GLANDS 403 



differentiation of the developing animals, the glands producing 

 them have been called " puberty " glands. 



The Corpus Luteum. — The corpus luteum is the name 

 given to what is really a temporary endocrine organ in the 

 mammals. After an egg has vacated its Graafian follicle, the 

 follicle undergoes changes resulting in the increase in size 

 of the follicular cells, and the invasion of the follicle by 

 connective tissue and blood-vessels. Should the egg liberated 

 not get fertilised, the corpus luteum soon disappears. Should 

 fertilisation result, however, and the blastocyst become 

 attached to the wall of the uterus, the corpus luteum persists 

 and increases in size, until the end of pregnancy. During this 

 time it produces a secretion the functions of which are to 

 prevent other eggs from being released from the ovary, and 

 to control the growth of the uterus and the secretion of milk. 



Literature 



Riddle, O. Internal Secretions in Evolution and Reproduction. The 



Scientific Monthly, vol. 26, 1928. 

 Swale Vincent. Internal Secretion and the Ductless Glands. Arnold, 



London, 1924. 



