INHERITANCE OF FECUNDITY IN DOMESTIC EOWI,- 325 



Matings: A. With 6 ? ? indicated to be of class i = fLiLi- Pkk. 



$ Progeny 



Winter Production: Over 30 Under jo Zero 



Observed 11 11 i 



Expected 11.^^ it. 5 



Mean winter production of 2 $ 



in indicated class ; 64.09 eggs 17.91 eggs eggs 



B. With 5 ? ? indicated to be of class 2 = fL,U FLJ-,. 



5 Progeny 



M^inter Production: Over 30 Under 30 Zero 



Observed 18 1 



Expected ig 



Mean winter production of 5 ? 



in indicated class 63.56 eggs i. 00 eggs 



All 2 Progeny 



Winter Production: Over 30 Under 30 Zero 



Observed 29 12 i 



Expected 30.3 11. 5 



Mean winter production 63.76 eggs 16.50 eggs o eggs 



Aside from the two outstanding exceptions the' agreement 

 between observation and expectation is excellent. From the 

 records available there is no evident explanation for the two 

 exceptions (the 'Zero' bird in the A matings, and the Tinder 

 30' bird in the B matings). Neither of the birds were bred, 

 and hence no help is to be had from the progeny in explaining 

 them. It is reasonable to suppose that the observed records for 

 these birds are somatic fluctuations, but this cannot be demon- 

 strated now. This case illustrates an unavoidable difficulty 

 which attends that method of work which first collects data at 

 random and without an}^ theoretical guide, and then later under- 

 takes their analysis. If one had been carrying on the breeding 

 in the present case under the guidance of the hypothesis as to 

 the mechanism of the inheritance of fecimdity now under dis- 

 cussion, obviously many matings which actually were not car- 

 ried out would have been made to test out somatically excep- 

 tional indivifhials and so learn their gametic constitution. 



