THE EFFECTS OF CASTRATION 133 



the development of these structures and colors is a by- 

 product of sex itself, and calls for no further explana- 

 tion. 



But the question cannot be so hastily dismissed. 

 This can best be shown by taking up at once the ma- 

 terial at hand. 



OPERATIONS ON MAMMALS 



In the deer, the facts are very simple. If the very 

 young male is castrated before the knobs of the antlers 

 have appeared, the antlers never develop. 



FIG. 67. Merino; male (horned) and female (hornless). 



If the operation is performed at the time when the 

 antlers have already begun to develop, incomplete 

 development takes place. The antlers remain covered 

 by the velvet and are never thrown off. They are called 

 peruke antlers. If the adult stag is castrated when 

 the horns are fully developed, they are precociously 



