APPLICATION OF PRINCIPLES OF BREEDING 481 



sections), the tendency is to make the decision of relative merits 

 turn on a few special features, to overvalue such features, and so, 

 by corresponding undervaluation of other features, to develop a 

 few favored characters at the expense of the rest. Many illustra- 

 tions of this kind might be given. There is hardly a variety in 

 the Standard that has not at some time suffered through such 

 partiality for some character. The most marked cases are those in 

 which the variety has lost popularity through the development of 

 a feature which finally became detrimental ; but the evil is by no 

 means confined to such. The craze for dead-white plumage for a 

 time made the white varieties conspicuous for lack of shape and 

 vitality. The craze for barring "to the skin" leads breeders of 

 Barred Plymouth Rocks to some neglect of shape and size. In 

 Leghorns and Polish the head points have been rated as high 

 as thirty per cent of the value of the specimen, with the result, in 

 case of the Leghorn, of so reducing size and neglecting shape of 

 body that the breed seemed at one time in danger of losing stand- 

 ing with the public. In breeding birds for exhibition the breeder 

 is forced to follow prevailing fads. Doing so does not necessarily 

 compel neglect of other characters, but as the fad develops it be- 

 comes more and more difficult to find and produce specimens 

 good in the favored section and also in other sections. 



Systems of selection. In selecting his breeding stock a poultry 

 breeder uses two principles, or systems, of selection, applying some- 

 times one, sometimes the other ; thus the common method of 

 selection is by irregular alternation of these systems. Selection by 

 a complex standard may be (i) progressive (or particular), consid- 

 ering certain characters or groups of characters always in the same 

 order, and rejecting from subsequent consideration all individuals 

 failing to meet requirements at any stage of selection, and (2) simul- 

 taneous (or collective), in which an effort is made to consider all 

 the more important characters collectively, balancing faults in some 

 against merits in others. It is not practicable to apply the progressive 

 principle to a great many characters, one by one. By a division of 

 characters into natural groups, with separate consideration of each 

 group and of the principal characters, and collective consideration 

 of all but the more important characters in a group, a simple and 

 effective working system of selection is developed. 



