INTERNAL SECRETIONS 



507 



more heat, or "oestrus/' in spayed animals. Further, the injection 

 of extracts of ovaries in an oestrus state, or the grafting of such into 

 these animals, produces the signs of heat in them. It is also stated 

 that as the result of transplantation of an ovary into the growing 

 male the teats and breasts become enlarged, and may even form milk. 



FIG. 241. SECTION THROUGH SUPRARENAL BODY OF DOG SHOWING ZONES OF CORTEX 

 AND MEDULLA. (Swale Vincent, drawn by Mrs. Thompson.) 



c, Capsule; /., medulla; z.f., zona fasciculata; z.g., zona glomerulosa; z.r., zona 



reticularis. 



The corpus luteum, into which a Graafian follicle develops after 

 discharge of the ovum, is believed to exert considerable influence by 

 yielding an internal secretion. This controls the fixation of the ovum 



