METHODS OF BREEDING 107 



practices grading in his herd because such animals usu- 

 ally are not for sale, and if they were he might not be 

 financially able to purchase them. The only advantage 

 that can be cited in favor of cross breeding is that the 

 pigs from such breeding are not likely to be inbred. 

 Hence they usually are fairly good individuals and, as 

 already said, may be as good as pure bred animals. Of 

 course a good cross bred pig is better than a poor pure 

 bred pig or a poor grade. To illustrate this, as well as 

 breeding in general, Cut 15 is presented. 



SWINE BREEDING. 



The cut on page 108 is not made from any experimental 

 data, or from any records whatever, but is simply an off- 

 hand drawing evolved in the mind of the writer to illus- 

 trate different degrees of breeding. The vertical dimen- 

 sions of the diamond-shaped figures represent de- 

 grees of variation in a breed, or in a herd, and 

 the distance of these above the base line the degree of 

 improvement. The dots within the figure represent the 

 individual pigs, as for instance the crop of pigs that is 

 produced in one season or the pigs of a breed. The hori- 

 zontal line through the diamond-shaped figure is to rep- 

 resent the average of the herd or of the breed. The dots 

 at the upper side of the axis of the diamond are to repre- 

 sent the pigs that are better than the average, while the 

 ones below the axis represent those that are poorer than 

 the average. 



It will be seen that the greatest number of the pigs are 

 similar in characteristics to the average of the breed or 

 herd, that those which are either better or poorer become 

 fewer in number as the distance from the center or aver- 

 age is increased. As will be seen, there are a compara- 



