118 H. D. GOODALE AND GRACE MACMULLEN 



ing them extensively to the several sorts of females, to see 

 whether or not large families could be obtained having the re- 

 quired ratios. 



SUMMARY OF CRITICISMS OF BOTH THEORIES 



In several places we have indicated difficulties encountered in 

 applying Pearl's theory of the inheritance of egg production to 

 our data and which affect the validity of that theory. Sufficient 

 data, however, are not at hand to wholly disprove the theory, 

 though the Cornish male by Rhode Island Red female cross 

 demonstrates that the theory is not of universal applicability. 



These difficulties mentioned, however, render necessary a 

 state of suspended judgment even in rspect to the applicability 

 of Pearl's theory to his own data. These difficulties may be 

 summarized here: 



1. The extremely small size of the individual families and the 

 various consequences that flow therefrom. 



2. Results of the Cornish, Rhode Island Red cross. 



3. Occurrence of high producers where none are expected. 



4. The too great ease with which abnormal production may be 

 made to fit theoretical ratios. 



5. The lack of class /, II, and V males mated to all sorts of 

 females with families of adequate size. 



6. The facility with which the several division points between 

 high and mediocre producers may be employed. 



Difficulties 1, 4, and 6 apply also to the alternative theory. 



CONCLUSIONS 



The conclusions to be drawn may be stated as follows: 



1. The mode of inheritance of winter egg production remains 

 to be determined. 



2. The validity of Pearl's theory can be settled only by breed- 

 ing operations conducted on a large scale, with disease and the 

 necessity of practical considerations eliminated. It should be 

 borne in mind, however, that as Pearl's mediocre producers are 

 birds that lay at a slow rate, irregularly and spasmodically, 



