FECUNDITY IN THE DOMESTIC FOWL AND THE 

 SELECTION PROBLEM 1 



DR. RAYMOND PEARL 

 I 



In the December number of the American Naturalist 

 Professor AY. E. Castle 2 directs a vigorous attack against 

 the present writer's work on fecundity. Any one reading 

 Professor Castle's article could scarcely fail, I think, to 

 carry away the impression that the whole of the writer's 

 studies of the past eight years on fecundity in the domes- 

 tic fowl are to be regarded as essentially valueless. I 

 assume that it was not the intention to convey this impres- 

 sion. The fact, however, appears to be as here stated. 

 With such a conclusion I can scarcely be expected to agree. 

 I shall therefore attempt, in the following pages, in the 

 first place, to call attention to some points regarding my 

 own work which Professor Castle appears to have over- 

 looked, and which seem calculated to give it at least some 

 slight degree of significance, and in the second place, to 

 set forth very briefly my reasons for venturing, in the 

 present state of knowledge, to hold a different opinion 

 from his in regard to some phases of the selection problem. 



II 



The general plan of Professor Castle's paper appears 

 to be to make a comparison between his selection experi- 

 ments with rats, and my selection experiments with poul- 

 try, to the very great disadvantage of the latter. To 

 this general comparison no general comment on my part 

 can be made, except assent to Castle's conclusion that his 



1 Papers from the Biological Laboratory of the Maine Agricultural Ex- 

 periment Station, No. 94. 



2 Castle, W. E., "Some Experiments in Mass Selection," Amer. Nat- 

 uralist, Vol. XLIX, pp. 713-737, 1915. 



