104 THE BREEDING OF ANIMALS 



believed that sows with rather long bodies are more fertile 

 than shorter, more compact individuals. It seems to be 

 true also that females having a somewhat loose and open 

 conformation are generally more certain breeders. 



The milking function of animals is in a measure corre- 

 lated with the quality of fecundity. Breeds of animals 

 and individuals which have the milking function well 

 developed are more fecund than those in which the devel- 

 opment of this quality has been neglected. Tanner, 1 

 in his interesting discussion on " The Reproductive 

 Powers of Animals," says : " The formation of milk is 

 intimately correlated with the reproductive powers. 

 The secretion of milk is dependent upon the activity of 

 the mammary glands and these are either under the direct 

 influence of the breeding organs or else they sympathize 

 very closely with them. Those animals which breed 

 with the least difficulty yield the best supplies of milk 

 and produce the most healthy and vigorous offspring." 

 He also adds that, " Since a short supply of milk is indica- 

 tive of and associated with enfeebled breeding powers 

 every care should be taken to obviate this defect." 



It must be admitted that our knowledge on the sub- 

 ject of characters correlated with fertility is as yet frag- 

 mentary and indefinite. The importance of this quality 

 in practical breeding should make this a fruitful field 

 for further investigation. 



102. In-breeding and fertility. Continuous in-breed- 

 ing among domestic animals has in many instances been 

 followed by low fecundity or absolute sterility. It is 

 generally believed by practical breeders that of all the 

 ill effects supposed to result from in-breeding, lessened 



1 Tanner, "The Reproductive Powers of Animals," Journal 

 of Royal Agricultural Society, 1865, p. 270. 



