PRAIRIE FARMER'S POULTRY BOOK 



can be traced to climatic influence. So, also, injury or dietary- 

 deficiency might account for foreign color in the plumage, 

 where none is found in the ancestry. Another factor is dis- 

 cordant elements that may have been introduced into the 

 blood somewhere along the line of ancestry. These crop out 

 and the law stated in paragraph one seems to be contradicted. 

 It is not, however, for the blood contains the very elements 

 which appear in the breeding. This tendency to revert to the 

 characters of the original ancestry is known as atavism, or 

 reversion, or "throwing back." I have in my flock of Reds a 

 Brown Leghorn pullet which was hatched from an egg of one 

 of my purebred hens. There has been no Brown Leghorn on 

 the farm for 12 years. This pullet seemed to drop out of a 

 clear sky. The cause is apparent. The Brown Leghorn was 

 one of the foundation breeds of the Rhode Island Red. By 

 the law of reversion this pullet was thrown on account of the 

 influence of ancestral blood. Strange things are liable to 

 happen under this law, yet it is true that like produces like. 



4. Variation. The more closely related the purebred sire 

 and dam and the closer the resemblance they have in type and 

 color, the less variation there will be in the progeny; that is, 

 the more closely the offspring will resemble the parents. De- 

 sirable characters have become fixed and the undesirable have 

 been eliminated. This small amount of variation is because 

 the blood lines are the same. This explains the advice some- 

 times given, that if a breed is to be improved or a new strain 

 established there must be close inbreeding, that the dam should 

 be bred to her own brother or her own sire if there is a close 

 resemblance in points of excellence. Many breeders believe 

 that this close inbreeding weakens the vitality and under- 

 mines the stamina of the progeny. On the other hand it is 

 urged that such a probability is prevented by selecting for 

 the sire and dam only individuals of marked vigor and vitality. 



5. Persistent and diminishing characters. Whatever the 

 mating may be, both .sire and dam will have imperfections. 

 These imperfections will show more or less in the progeny. If 

 the desirable characters overbalance the imperfections the 

 mating will be considered a success'; and if, as the breeding 

 continues, the imperfections gradually disappear and the good 

 qualities are intensified, then the breeder knows that he will 

 be able to establish a worthy strain. If on the other hand the 

 imperfections grow stronger and the desirable characters 



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