264 PRACTICE OF POULTRY BREEDING 



the creaminess, but the large deposit of fat under the skin gives 

 the white plumage a yellowish tinge. 



It is also caused in many cases by the "burning" of the white 

 plumage during the summer when the birds are exposed continu- 

 ously to the rays of the sun. Most of the noted breeders of exhi- 

 bition white birds keep them confined practically all the time, 

 letting them out only toward night. 



Soil Effects on Plumage and Shank. — The presence of certain 

 alkalies in the soil may make it almost impossible to secure t^e 

 greatest degree of color in plumage and shanks. In certain sections 

 it is impossible to get and keep the clear yellow shank, owing to the 

 presence of alkalies in the soil. Certain highly colored soils, of 

 a clay or shale nature, are a great hindrance to the breeder by 

 compelling him to confine his birds. (For further discussions on 

 breeding for color see references, page 265.) 



Breeding Fallacies. — There are two alleged facts in breeding 

 which should be explained. 



The influence of a previous sire or impregnation on the charac- 

 ter of subsequent chicks. In the case of fowls, even after a cock 

 bird has been removed from the pen he may become the parent 

 of chicks hatched from eggs subsequently laid by these hens, for 

 the sperm continues active within the hen for from ten days to 

 two weeks. But if, after the eggs laid have ceased to be fertile, 

 a new cock be added, different from the first, there is no proof 

 of any influence of the previous male bird. Experiments by Waite 

 show that at least three weeks must elapse before one can be sure 

 that the effect of a previous mating has ceased. 



Another alleged effect is that of imagination upon the subse- 

 quent progeny. For example, there is no ground for believing 

 that, if two pens of birds, one black and the other white, run side 

 by side, any splashing or mixing shown in the progeny is due to 

 the effect of sight or imagination. A more sane hypothesis would 

 be that the opposing cock bird jumped the fence and fertilized 

 the eggs. 



Steps in Pedigree Breeding. — The importance of using proper 

 steps in pedigree breeding is fundamental. The steps are : 



1. A simple method of identifying adult birds, usually by 

 means of leg bands or marks in the web of the feet. 



2. Use of trap-nests to determine eggs laid by individual hens 

 in various matings. 



3. Marking each egg as laid with the distinguishing mark of 

 the hen laying same. 



