No. 534] FECUNDITY IN THE DOMESTIC FOWL 323 



shown that it is capable of a satisfactory and reasonable 

 interpretation on the genotype hypothesis, and East and 

 Shull have gone far in the analysis of genotypes in 

 maize. This, however, is only a beginning. There is the 

 greatest need for careful, thorough investigations of the 

 inheritance of characters showing marked fluctuating 

 variation in organisms having the sexes separate. Here 

 lies one of the crucial fields in the study of inheritance 

 to-day. Through the brilliant results in Mendelian di- 

 rections and from the study of really "pure" lines we 

 are getting clear-cut ideas as to the inheritance of quali- 

 tatively differentiated characters, such as color, pattern 

 and the like, on the one hand, and in regard to the in- 

 heritance of quantitative variation in self-fertilized or 

 non-sexually reproducing organisms, on the other hand. 

 But beyond all these lie the difficult cases where in dioe- 

 cious forms quantitative variations must be dealt with. 

 If these can be cleared up and brought harmoniously 

 into a general scheme or view-point regarding inherit- 

 ance, we shall have gone a long way in the solution of 

 this world-old biological problem. 



For some four years past the writer has been engaged 

 in a study of the inheritance of fecundity in the domestic 

 fowl. The problem presented here is an important one 

 from the practical as well as the theoretical standpoint. 

 If definite and sure methods of improving the average 

 egg production of poultry by breeding can be discovered 

 it will mean much to the farmers of the nation. At the 

 same time egg production is a character in some ways 

 well adapted to furnish definite and crucial data regard- 

 ing inheritance. Variations in egg production are read- 

 ily measured, and can be directly expressed in figures. 



The general results of this study of the inheritance of 

 fecundity may be said, in a word, to be, so far as they go, 

 in entire accord with the genotype concept, and not to 

 agree at all with the "statistico-ancestral" theory of in- 

 heritance. Indeed, so ill is the accord here that the chief 

 exponent of the latter doctrine has recently attempted to 



