No. 552] INHERITANCE OF FECUNDITY 



707 



races or breeds of poultry than those used in the present 

 experiments may show a somewhat different scheme of 

 inheritance of fecundity. The directions in which devia- 

 tions from the plan here found to obtain may, at least 

 a priori, most probably be expected are two. These are : 

 (a) differences in different breeds in respect to the abso- 

 lute fecundity value of the factors which determine the 

 expression of this character, and (&) gametic schemes 

 which differ from those here found either in the direction 

 of more or fewer distinct factors being concerned in the 

 determination of fecundity, or in following a totally 

 different type of germinal reactions. 



Regarding the first point, it seems probable from the 

 evidence in hand that the absolute fecundity value (i. e., 

 the degree of actual fecundity determined by the presence 

 of the gametic factor) may differ for the factor L t in the 

 case of the Barred Rock as compared with the Cornish 

 Indian Game breed. It is hoped later to take up a detailed 

 study of this point, on the basis of the material here pre- 

 sented, and additional data now in process of collection. 

 "Whenever there is a difference in the absolute fecundity 

 value of the factor, it means that the division point 

 for the classification of winter productions should be 

 taken at a point to correspond with the physiological 

 facts. Similarly, the absolute fecundity value of the 

 excess production factor L 2 may be different in different 

 breeds. In applying the results of this paper to the pro- 

 duction statistics of other breeds of poultry the possi- 

 bility of differences of the kind here suggested must 

 always be kept in mind. 



The second point (the possibility of gametic schemes 

 for fecundity differing qualitatively from that found in 

 the present study) is one on which it is idle to speculate 

 in advance of definite investigations. I wish only to 

 emphasize that nothing is further from my desire or in- 

 tention than to assert before such investigations have 

 been made that the results of the present study apply 

 unmodified to all races of domestic poultry. 



