Essentials of Animal Breeding. 



37 



laws for the explanation of the 'facts which they observe and not 

 try to explain them as due to supernatural causes. To summarize 

 very briefly, let us bear in mind the following fundamental facts : 



1. All animal forms on the earth have developed gradually from 

 lower forms by very slow changes. This is the process known as 

 evolution. 



2. The young animal starts on its career when two bits of heredi- 

 tary material (germ plasm) unite, one from the female (the egg) 

 and the other from the male (the sperm). When the union is com- 

 plete, the sex, identity, and individuality of the animal are settled. 

 Chance plays a most important part in determining these factors. 



3. From now on the fate of the animal depends on its nourish- 

 ment and environment. 



Why Cloud a Boy's Dreams With This Kind of Stock? 



FIG. 32. Give the youngsters well-bred pigs, calves, sheep, and chickens, and they will 

 be much more likely to stay on the farm and become producers of useful, profitable 

 animals to the advantage of their own pocketbooks and the wealth of the Nation. 



4. The breeder can do much to bend the operations of the laws 

 of chance to his own ends by careful selection of breeding stock. 

 u Breed the best to the best." 



5. Next to selection the best means at the command of the breeder 

 to fix type in his animals is inbreeding. It is a powerful tool, but 

 a dangerous one in unskillful hands. Inbred sires are more im- 

 pressive as a rule than sires which are not inbred. 



6. Nature does not work lawlessly. Occurrences attributed to 

 supernatural means can be more rationally explained as a manifesta- 

 tion of some operation of a law of heredity. 



If a breeder has a clear conception of these facts, he can usually 

 explain by one or the other nearly every occurrence which he may 

 observe. The clearer he thinks on these subjects the more successful 

 he will be as a breeder. 



