INHERITANCE OF WINTER EGG PRODUCTION 119 



while mine are mainly birds of late maturity, that the numerical 

 results obtained may be wholly valid for his strain. Moreover, 

 in the Barred Plymouth Rocks the winter cycle of production 

 is a characteristic feature of nearly all records. It, therefore, 

 remains entirely possible that Pearl's theory is fully applicable 

 to his particular strain of Barred Plymouth Rocks, in which 

 case it should be stated as a theory of the inheritance of rate of 

 production during the winter cycle. Looked at from this angle, 

 then, it is apparent that Pearl's theory may be a complete 

 explanation of this phase of the inheritance of egg production. 

 Although our numerical data are similar to those of Pearl, we 

 believe that the methods used in this paper are wholly inade- 

 quate for the solution of the problems of inheritance of egg pro- 

 duction. On the contrary, the problems should be approached 

 from an entirely different angle, namely, that of the inheritance 

 of the several factors, whose combined action results in a given 

 number of eggs for the winter period (compare Goodale, '18). 



SUMMARY 



1. The data furnished by the flocks of Rhode Island Reds at 

 this station furnish ratios that agree with those expected on 

 Pearl's theory of the inheritances of fecundity. 



2. A division point at 40, 50, or even 60 eggs gives ratios that 

 agree well with the observed ratios. 



3. An alternative theory that recognizes two classes of winter 

 egg production, viz., high and mediocre, and assumes two genes, 

 both of which must be present in the female zygote in order to 

 have high production, and which are inherited according to the 

 Mendelian dihybrid scheme, will also account for the observed 

 ratios. 



4. Reasons are presented, showing that the applicability of 

 these schemes may depend upon the small average number of 

 offspring produced by each pair of parents. Methods by which 

 the falsity or truth of these schemes may be established are 

 given. 



