INHERITANCE OF FECUNDITY 219 



bird was made, the fact of her abnormahty not having been 

 recognized until too late to make such an examination possible. 



It was mifortunate that & 550 could not have been used during 

 several breeding seasons. Even with the limited progeny actually 

 available, however, the contrast between this bird and the others 

 which have been discussed above is sufficiently striking. 



Doubtful cases. In 1908 a Barred Plymouth Rock cT no. 61 

 was successfully mated with 3 9 9. The winter production records 

 were as follows: 



Mothers' winter -production Daughters' winter production 



9 D157 Under 30 1 over 30 under 30 zero 



9 D168 Over 30 2 over 30 10 under 30 1 zero 



9 D90 Under 30 2 over 30 5 under 30 zero 



The case is a difficult one, because of the behavior of certain oi 

 the daughters in subsequent matings. The most probable inter- 

 pretation of the facts is that cr" 61 belonged to class 4, and that 

 D 168 is a 9 of class 1, but that in certain of her daughters bearing 

 Lo, this character did not come to full expression, giving a winter 

 record of under 30. Three of the 10 daughters of 9 D168 re- 

 corded as 'Under 30' laid 25 or more eggs in the winter period. 

 If we suppose these to be really Lo birds, we should then have the 

 following gametic distribution of 168's daughters. 



Winter Production : 



Observed 



Expected 



This is as close as could be expected. 



Female D90 may be of either class 3 or 4. The data at hand 

 do not enable one to determine with certainty between these 

 possibilities. Female D157's only daughter left no adult 9 

 offspring, and therefore it is not possible to make any conjecture 

 as to her constitution, beyond the fact that she was probably not 

 of class 1 or 2. 



In the case of a number of males the families of adult daughters 

 obtained were so small in size as to make impossible any accurate 

 determination of the gametic constitution of the mothers used. 

 All of these cases are here grouped together in one table. 



