arose as a necessity on account of the danger of introduct- 

 ion of impure blood, wherQ impure individuals were com- 

 mon, and the great loss attending such introduction. 



In late years Advanced Registers have been formed in 

 which Performance is the basis of registration. 



Unrecorded animals may be (1) scrubs, those with 

 mixed strains, and (2) unregistered, or those of pure strains 

 but whose records have been lost, and whose ancestry in us- 

 known. 



Systems of Breeding.~ln general four systems are 

 practised : 



(1) Mixed breeding, where no attention is paid to 

 ancestry. In this system evidently no improvement can 

 take place or be expected. 



(2). Pure breeding, where only registered animals are used. 



(3) Grading, where only the sire is pure-bred. By care it 

 is possible to build up a sound herd without much trouble or 

 expense. With every succeeding generation the animals are 

 becoming more and more pure-bred. For economic pro- 

 duction such high-grade animals are equal to pure-breed. 



Discuss Co-operative Breeding. 



(4) Crossing, where pure breds of different races are cross- 

 ed. This system is not recommended except for the modifi- 

 cation of a breed ,with the chance of getting an improved 

 form. 



"Breed in to fix type; breed out to secure vigor; in gen- 

 real, compromise "sums up fairly accurately the experience 

 of breeders. 



It will be observed that the splendid achievements of 

 animal breeders have been made without a knowledge of 

 genetics as it is understood by the scientists of to day. The 

 lore of the breeder's craft is to a large extent the valuable 

 body of experience accumulated through long centuries after 

 repeated failures and successes. It differs from genetics in 

 that it gets results through the adoption of traditional rules 

 or methods while the latter seeks for the natural laws that 

 underlie and explain the methods. In this way genetics 

 often breaks down old erroneous ideas, suggests new meth- 

 ods, and makes for future progress in the art of breeding . 

 The best results, of course, will be secured when the breed- 

 er is thoroughly acquainted with both the art and the 

 science of breeding. 



