144 POULTRY-CRAFT. 
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: (1) 
The law of heredity; of family, or race, likeness; and (2) Zhe 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. 
‘¢ Heredity ” is the inheritance of /¢ke 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: (1) 
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 
*Notre.—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. 
