lo March, 1909.] The Dairy Bull. i35 



The onh' variation is that the deteriorating effect is postponed until the 

 progeny of the second bull matures. In such a case it is almost a cer- 

 tainty that the breeding of this second bull would be blamed for any such 

 deterioration ; whereas the whole trouble would be in the mongrelLzing 

 result which had thus thoughtlessly been brought about by the owner. 



Breeders of stock recognise several laws which apply to all animals. 

 Among these are the laws of " heredity " and " atavism." _ The former 

 is explained to a certain extent by the phrase " like begets like." This 

 law is reliable only when dealing with pure-bred stock of known breeding 

 and fixed traits of character. By atavism, on the other hand, is meant 

 a reversion to the type of some more or less remote ancestor. The occur- 

 rence is commonly known as " throwing back." The result is the 

 revival of some tendency which had previously been eliminated by per- 

 sistently breeding against it. All domestic animals have their origin in 

 ^ome wild species. Through many generations past breeders of cattle 



RESULT OF JUDICIOUS MATING. 



have culled out animals that showed undesirable characteristics, and bred 

 only from such as possessed those which it was sought to perpetuate. In 

 this way the various breeds have been formed and perfected, but behind 

 them all lies their wild ancestry. If stock are permitted to breed indis- 

 criminately they tend to revert towards their original types with amazing 

 Tapiditv ; thus showing the potency of this power of ' ' atavism ' ' or 

 "throwing back"; or, in other words, the strength of the blood of the 

 original species. Where a breed has been kept pure for a long period 

 the tendency to atavism is held in check. One object, therefore, of 

 maintaining and intensifying purity of breeding in dairy stock is to 

 prevent reversion or throwing back to an undesirable type. 



The dairy-farmer, therefore, who uses any other than a pure-bred dairy 

 bull is working backwards from year to year ; and, in the end. he must 

 ■either give up dairying or begin over again by buying fresh stock. On 



