IN THE BREEDING CLASSES 47 



ewe's face is finer and the neck much lighter. In swine the 

 boar's head is short and inclined to coarseness and the tusks 

 are strong and large. The neck is full and the bristles 

 abundant and with age the shields (thickening of the hide 

 over the shoulder blades) develop. The sow is smaller in 

 the face, the neck much lighter and finer just at the point 

 where it joins the head. These things are all features of the 

 sex characteristics and their value, which will be discussed 

 in what follows, will indicate the degree to which they should 

 be looked for in all breeding classes. 



79. Relation of Sex Characteristics to Sterility. When the 

 sex characteristics that have been described fail to develop 

 in the mature animal, it is invariably good evidence of the 

 lack of procreative power. The effect of castration is evi- 

 dence of the fact that if anything interferes with the maturity 

 of the reproductive organs, the sex characteristics fail to 

 develop. If the operation is performed early in life there is 

 a decided approach to the characteristics of the feminine type 

 in the instance of geldings, steers, wethers and barrows. 

 On the other hand, it is equally true of the opposite sex 

 thwarted or impaired development results in the production 

 of the characteristics that are peculiar to the male type. As 

 an instance of this the occurrence of ' ' free martins ' ' in cattle 

 may be cited. This term is applied to twins in which the one 

 is a male and the other a female. The female usually pos- 

 sesses the sex characteristics of the male as she has the coarse 

 appearance in the head, neck and horn, and when this is so 

 it will be found that she is invariably infertile. Extreme 

 effeminacy on the part of the male is equally indicative of 

 sterility as may be attested to by the effeminate appearance 

 and the sterility that results from inbreeding some classes of 

 stock. Low, referring to this says of closely in and inbred 

 animals, ' ' They become as it were sooner old; the males lose 

 their virile aspect and become at length incapable of recreat- 

 ing their race." Walker (Intermarriages) cites many 



