inheritance: of fecundity in domestic fowl. 379 



exists betAveen birds of high fecundity and those of low fecun- 

 dity. 



6. It is found to be the case that birds fall into three well- 

 defined classes in respect to winter egg production. These in- 

 clude (a) birds with high winter records, (&) birds with low 

 winter records, and (r) birds which do not lay at all in the 

 winter period (as defin-ed above). The division point between 

 a and h for the Barred Plymouth Rock stock used in these 

 experiments falls at a production of about 30 eggs. 



7. There is a definite segregation in the Mendelian sense of 

 the female offspring in respect to these three fecundity divi- 

 sions. 



8. High fecundity may be inherited hy daughters from their 

 sire, independent of the dam. This is proved by the numerous 

 cases presented in the body of this paper where the same propor- 

 tion of daughters of high fecundity are produced by the same 

 sire, whether he is mated with dams of low or of high fecundity. 



9. High fecundity is not inherited by daughters from their 

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

 lines of evidence, of which the most. important are: (a) contin- 

 ued selection of highly fecund dams does not alter in any way 

 the mean egg production of the daughters (26, ly, 28, 30, 34, 

 35> 3^. Z?) ; (^^^ the proportion of highly fecund daughters is 

 the same whether the dam is of high or of low fecundity, pro- 

 vided 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 loiu 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 

 daughters 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 



" This is true, of course, only for certain gametic types of low fecun- 

 dity 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 begin- 

 ning of paragraph 9. 



7 



