260 KAYMOND PEARL 



worth of the factors which determine the expression of this char- 

 acter, and (6) gametic schemes which differ from those here found 

 either in the direction of more or fewer distinct factors being con- 

 cerned in the determination of fecundity, or in following a totally 

 different type of germinal reactions. 



Regarding the first point it will be recalled that in several places 

 in the body of the paper it has been suggested 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 

 Li 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 presented, and 

 additional data now in process of collection. Wherever there is a 

 difference in the absolute fecundity value of the Li factor, it 

 means that the division point for the classification of winter pro- 

 ductions should be taken at a point to correspond with the physio- 

 logical facts. In this first study the division at 30 eggs has been 

 found to accord sufficiently well for practical purposes with the 

 actual facts. Similarly the absolute fecundity value of the excess 

 production factor L2 may be different in different breeds. In 

 applying the results of this paper to the production statistics of 

 other breeds of poultry the possibility of differences of the kind 

 here suggested must always be kept in mind. 



The second point (the possibility of gametic schemes for fecun- 

 dity differing qualitatively from that found in the present study) 

 is one on which it is idle to speculate in advance of definite inves- 

 tigations. I wish only to emphasize that nothing is further from 

 my desire or intention than to assert before such investigations 

 have been made that the results of the present study apply un- 

 modified to all races of domestic poultry. 



It cannot justly be urged against the conclusions of this study 

 that the Mendelian hypothesis advanced to account for the 

 results is so complicated, and involves the assumption of so 

 many factors or such complex interactions and limitations of 

 factors, as to lose all significance. As a matter of fact the whole 

 Mendelian interpretation here set forth is an extremely simple 

 one, involving essentially but two factors. This surely does not 



