BREEDING POULTRY FOR EGG PRODUCTION. I23 



Furnished with a quahtatively inadequate food supply the 

 developing embryo either dies before hatching or hatches into 

 a weak, debilitated chick. This badly nourished, weak chick 

 grows into an adult fowl which is weak in constitution ; usually 

 weaker and to a greater degree lacking in vitality than the 

 parent. The reason is that the unfavorable environmental fac- 

 tor has had a double action upon the adult offspring. Not only 

 did it start life as an improperly nourished weak embryo, but 

 throughout its post-embryonic development to the adult condi- 

 tion the same unfavorable environment which acted adversely 

 upon its mother has been acting upon it and undoubtedly with 

 increased efficiency because of the initial weakness of the 

 embryo. This offspring bird may thus be expected to produce 

 a still less normal supply of nutriment in its eggs than did its 

 mother, since it is less vigorous and normal than she was.* 



Thus the weakness is passed on from generation to genera- 

 tion tending all the time to become greater, I think that it must 

 be obvious in view of these considerations that any environ- 

 mental condition which is adverse to general constitutional 

 vitality, if it is effective at all, must tend to become cumulatively 

 so, even though every effort be made to keep environmental 

 conditions uniform during the experiment. In fact the more 

 uniform the environment is kept the more certainly will there 

 be a cumulative effect of any unfavorable factor in it. 



Obviously such a result as that under discussion has no real 

 relation to the problem of the inheritance of acquired characters, 

 though the objective result itself is precisely that which would 

 be expected if a weakness induced by the environment were 

 inherited. But actually the factor here dealt with is a purely 

 nutritional one, and has nothing whatever to do with germinal 

 constitution. This fact that any adverse environmental factor 

 tends to produce an effect on the organism (at least among 

 birds and marrimals) which is persistent and in greater or less 

 degree progressively cumulative, so long as the environment is 



* Certain of these matters are being made the object of special inves- 

 tigation from a practical standpoint by Prof. Rice of Cornell University. 

 Cf. Rice, J. E., and Rogers, C. A., Importance of Constitutional Vigor 

 in the Breeding of Poultry. Cornell Reading Course for Farmers. No. 

 45. 1909 pp. 777-796. 



