144 POUL TR r- CRA FT. 



CHAPTER X. 



Principles of Breeding, Selection and Care of 

 Breeding Stock. 



193. The Law of Inheritance. The principles of breeding being 

 based on one universal law, the law of inheritance, the transmission of 

 qualities in generation, a correct appreciation of this law is essential to a 

 right understanding of the principles of poultry breeding. In its operation 

 the law of inheritance shows, always, two phases which appear to result from 

 conflicting laws. Thus while fowls of the same pure breed produce offspring 

 unmistakably like themselves, the offspring are never exactly like either parent, 

 or like each other, so that it is commonly said that there are two laws : (i) 

 The law of heredity; of family, or race, likeness ; and (2) The law of 

 variation, of individual diversity, and it is considered that " heredity" and 

 " variation " are visible effects of opposing forces, the first working to preserve 

 a race as it has existed, the second to produce change ; and that these forces, 

 especially that which controls variation, work in some mysterious capricious 

 way which the breeder cannot fathom. 



There are not two laws. There is but one : the law of inheritance. 

 u Heredity " is the inheritance of like qualities ; *' variation " the inheritance of 

 unlike qualities,* and it is as strictly in accordance with the law of inheritance 

 that the unlike characteristics, the individual differences, should pass from 

 generation to generation with changing kaleidoscopic effects as that the like 

 qualities should be transmitted practically unchanged. 



194. One Law Explains All the Phenomena of Reproduction. 



Congenital, or inherited, variations may be divided into three classes : ( i ) 

 Slight variations, differences in degree of like qualities; (2) Considerable 

 variations either extraordinary development or degeneracy of a race quality, 

 or, a new quality which is at once recognized as resulting from a union of 

 ancestral qualities; (3) Variations, which constitute new qualities not 

 traceable to known ancestors, or to supposedly possible combinations. It was 

 only necessary to make such a classification of congenital variations to show 



*NOTE. In this generalization acquired variations must be excepted. Acquired 

 variations which are directly due to external causes are the initial variations, the begin- 

 nings of differences between individuals, and are inheritable. 



