28 OUR DOMESTIC BIRDS 



ten years, according to the number of characters to be estab- 

 lished as distinctive of the variety. Varieties are also made by 

 crossing unlike individuals. This process is longer than the 

 other, and sometimes requires a series of crosses to produce 

 specimens approximating the ideal sought. After such speci- 

 mens have been obtained the method is the same as in the first 

 case. A variety is commonly considered to be well established 

 when the greater part of the specimens produced are easily 

 identified as of that variety. But no domestic variety is ever 

 established in the sense that a species is. All are artificial, pro- 

 duced by compulsory separation and preserved only as long as 

 it is continued. 



Classification of domestic varieties of birds. Domestic varie- 

 ties of all kinds of live stock were at first mostly shape-varieties ; 

 that is, the individuals of a variety were alike in shape but of 

 various colors. This is the case still with some varieties. These 

 shape-varieties are mostly the common types of certain countries 

 or districts. Thus the Leghorn fowl is the common fowl of 

 Italy, and the Houdan is a type common in a small district in 

 France. Such shape-varieties are called breeds. When other 

 types were made by crossing such breeds they also were called 

 breeds. 



When people first began to be interested in the improvement 

 of live stock, the popular idea of a breed was that it was a dom- 

 estic species, and there are still many people who hold this view. 

 This popular misconception of the nature of a breed is respon- 

 sible for much of the inconsistency and confusion in the ordinary 

 classifications of domestic varieties. To it also is due the use of 

 the term " variety " to apply especially to color- varieties, which 

 are the principal divisions of breeds. 



In the classification of domestic birds a variety is properly a 

 color- variety of a breed. Thus in the Plymouth Rock breed there 

 are six color-varieties barred, white, buff, partridge, silver pen- 

 ciled, and ermine (called Columbian) ; and in Fantail Pigeons 



