PRINCIPLES OF POULTRY BREEDING 65 



variation was continuous, or, if a sport or mutation did ap- 

 pear, it would suddenly disappear. In other words, all im- 

 provement was the result of selection selecting the best, 

 generation after generation, until finally the desired type 

 or characteristics became firmly fixed. This was the theory 

 of Darwin; but it has been shown that all improvement 

 is not a slow evolutionary process; that it is not all a 

 matter of selection, but that a new type may suddenly 

 appear and start a new variety or a new breed. The 

 vast majority of ''sports" or mutants may not breed 

 true; they may disappear as suddenly as they came, 

 but the breeder with a knowledge of the history of 

 new varieties of plants and animals will carefully test any 

 variations that point to higher excellence. 



During the past half century at least one breed of fowls 

 owes its existence to the appearance of the mutant. A white 

 "sport" came from a dark breed and resulted in one of our 

 popular breeds. The mutant may disgrace the yard of the 

 fancier who is breeding for uniformity, but the breeder who 

 wishes to perpetuate new and desirable characteristics or 

 establish a new breed must be on the lookout for and care- 

 fully preserve such characteristics when they appear. 



Two-hundred-egg hens may or may not breed true. Some 

 of them may and some may not, but the progressive breeder 

 will take his chances. So far as it is now known, it is a 

 chance, and the sure way to determine whether one hen or 

 one male will breed true is to test them in the breeding pen. 



Reversion. Variation, however, is not always in the line 

 of progress. Sometimes the offspring may vary away from 

 the line of improvement. Sometimes characteristics that have 

 a counterpart only in remote ancestors, appear suddenly. 

 This is called reversion or breeding back. The scientific 

 name is atavism. What causes reversion is one of the great 

 mysteries. There is a latent tendency, largely unknown, 



