360 MAINE AGRICUIvTUR7\Iv EXPERIMENT STATION. I912. 



the study of inheritance is concerned. A definite structure 

 either is or is not present in the zygote, however weak physio- 

 logically the individual may be. But if the general capability 

 of an organism with respect to the transformation of matter 

 and energy is markedly reduced, then all physiological charac- 

 ters will be affected, and fail to reach complete normal expres- 

 sion. 



In the study of cross-bred poultry I have found pure extract- 

 ed whites from crosses involving originally two heavily pigment- 

 ed parent races to be conspicuously good examples of the phe- 

 nomenon under discussion. It is only very exceptionally, in my 

 experience, that such white birds are physiologically normal. 

 Indeed because of this fact it is only with the greatest difficulty, 

 and after many failures, that I have been able tO' get such ex- 

 tracted whites to breed, and thus form a pure white race. If the 

 hens lay eggs, which some do not do, they are usually either 

 infertile, or else all the embryos die at an early stage. These 

 facts have some bearing on the popular belief of animal breed- 

 ers that whites in general are delicate in constitution and hard 

 to rear. This belief is so well known that it is not necessary to 

 cite in detail references regarding It in the literature. 



As a consequence of the above considerations, I have felt 

 justified in leaving out of account, or rather in considering apart 

 from the others, a few of the F-^ individuals, in all some 7 out 

 of over 200 P.i birds all told. In each case these birds were 

 physiologically abnormal, and obvioush^ so to the most casual 

 observer. The fact that they did not lay was no criterion what- 

 soever of their hereditary constitution. In order that there 

 might be no possibility oi unfairly influencing ratios by leaving 

 these birds out, the whole families T usually of two or three in- 

 dividuals only) to which they belonged have been rejected. As 

 a matter of fact whenever one individual in a family is physio- 

 logically abnormal in this way a)l the other members will usually 

 show the same condition in greater or less degrees. 



In the p2 generation following the reciprocal crossing of 

 Barred Rocks and Cornish Indian Games there are a number of 

 possible matings. The nature of these matings and the results 

 as to color and pattern have been discussed in another place 

 (41). That paper may be referred to in case one is not clear as 



