l.\ THE BREEDING CLASSES 47 



of the ram is shorter and heavier and the neck has a heavy 

 ''scrag" or crest. The ewe's face is finer and the neck 

 much lighter. In swine the boar's head is short and in- 

 clined 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 character- 

 istics and their value, which will be discussed in what fol- 

 lows, 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 evi- 

 dence of the lack of procreative power. The effect of 

 castration is evidence of the fact that if anything inter- 

 feres with the maturity of the reproductive organs, the 

 cex characteristics fail to develop. If the operation is per- 

 formed early in life there is a decided approach to the 

 characteristics of the feminine type in the instance of geld- 

 ings, 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 characteris- 

 tics 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 possesses 

 the sex characteristics of the male as she has the coarse 

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

 ::o it will be found that she is invariably infertile. Ex- 

 treme effeminacy on the part of the male is equally indic- 

 ative 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 



