INHERITANCE OF FECUNDITY 253 



9. High fecundity is not inherited by daughters from their 

 dam. This is proved by a number of distinct and independent 

 hues of evidence, of which the most important are: (a) continued 

 selection of highly fecund dams does not alter in any way the mean 

 egg production of the daughters (26, 27, 28, 30, 34, 35, 36, 37) ; 

 (6) the proportion of highly fecund daughters is the same whether 

 the dam is of high or of low fecundity, provided both are mated to 

 the same male;^" (c) the daughters of a highly fecund dam may 

 show either high fecundity or low fecundity, depending upon their 

 sire; (d) the proportion of daughters of low fecundity is the same 

 whether the dam is of high or of low fecundity provided both are 

 mated to the same male. 



10. A low degree of fecundity may be inherited by the daugh- 

 ters from either sire or dam or both. 



11. The results respecting fecundity and its inheritance stated 

 in paragraphs 3 to 10 inclusive are equally true for Barred Ply- 

 mouth Rocks, Cornish Indian Games, and all cross-bred combi- 

 nations of these breeds in Fi and Fa.^^ 



The above statements are of definite facts, supported by a 

 mass of evidence. Their truth is objective and depends in no way 

 upon any theory of inheritance whatsoever. With this clearly 

 in mind we may undertake their interpretation. 



It is believe that these general facts, and the detailed results on 

 which they are based, are completely accounted for and find their 

 correct interpretation in the simple Mendelian hypothesis respect- 

 ing the inheritance of fecundity in the fowl, which was outlined 

 at the beginning of this paper and has been checked against the 

 detailed data from each mating. This hypothesis involves the 

 following points, each of which is supported by direct and perti- 

 nent evidence derived either from physiological and statistical 



" This is true, of course, only for certain gametic types of low fecundity females, 

 as will be clear to anyone who has studied the detailed evidence. This limitation, 

 however, in nowise diminishes the force of this particular evidence in favor of the 

 conclusion standing at the beginning of paragraph 9. 



1^ And F3. It has not been thought wise to delay publication of this paper any 

 longer in order to include the data for F3. It may be said however that they are in 

 full accord with those which have been obtained from earlier cross-bred genera- 

 tions and the parent forms. 



