296 



HORMONES 



and the appearance of male characteristics pecuHar to the species. In 

 man these include a typical distribution of body hair, deep voice, mascu- 

 line shape of body and muscular development, and growth of the beard. 

 Substances producing these effects are called androgens, or androgenic 

 hormones. A typical effect is shown by androgens on the growth of the 

 comb and wattles of the chick (Fig. 11-4). This response has been 



Courtesy of University of Wiscon.sin, Department of Poultry Husbandry. 

 Fig. 11-4. Effect of androgen on growth of comb and wattles of imma- 

 ture cockerels. Both birds were 19 days old when photographed, but the 

 one on the right had been treated with 15 mg. of testosterone propionate 

 9 days previously. 



!■ 



made the basis for a quantitative assay method. 



Chemical Nature. The chemical formulas of the more important sex 

 hormones obtained from natural sources are given below: 



Estrogenic hormones 



