INHERITANCE OF FECUNDITY 211 



In this case, while the number of successful matings was small, 

 the families were relatively large. In the case of 9 366, set down 

 here as probably of class 6, it should be said that this conclusion 

 as to her gametic constitution is reached from a study of her 

 daughters' and granddaughters' behavior. Her own winter egg 

 record was 33, which on this view is regarded as a somatic fluctua- 

 tion from the Li (Under 30) class. 



B.P.R. d" 68. Indicated constitution = /L1L2 . JULo. 



As in the case of cf 65 nothing is known regarding the breeding 

 of this bird, it having been purchased from Mr. Geo. W. Hillson, 

 of Amenia, N. Y., early in 1908. It was bred as a cockerel the 

 same season. The only matings to get adult daughters were 

 those with class 1 females. The breeding history is as follows : 



Matings: A. With 4 9 9 indicated to be of class 1 = /L1L2 . Fhh. 



All 9 Progeny 



Winter Production: Over 80 Under 30 Zero 



Observed 13 5 2 



Expected J 5 5 



Mean winter production of all 



9 9 in indicated classes 59.00 eggs 25.20 eggs eggs 



The facts regarding the two zero birds here are of interest. 

 According to theory no bird of this class should appear from any 

 of these matings. One of these zero birds, E192, laid her first 

 egg March 4, 1909, and proved thereafter, during the reproduc- 

 tive period (March 1 to June 1) to be a fairly good layer, with a 

 total production for the period of 51 eggs. 



Her laying during this a^ad the subsequent summer period both 

 in respect to its amount and its distribution, impresses one as 

 like that of a bird carrying Li, rather than hke that of a 'genetic' 

 zero winter layer lacking this factor. I am of the opinion that 

 this was the case. This bird, on such a view, would represent an 

 extreme physiological variant in respect to the beginning of lay- 

 ing. While apparently bearing Li this factor did not come to 

 expression until much later than under normal circumstances. 



The other zero bird was pathological in respect to her repro- 

 ductive organs. She never laid an egg and died July 16, 1909. 



