246 RAYMOND PEARL 



the following figures. In the case of pure C.I.G. matings the 

 factor Li is not present. All females in the 'Under 30' class are 

 therefore either L]Z] or LyLi in type. The mean winter pr duc- 

 tion of all pure C.I.G. ? 9 in the 'Under 30' class is 10.22 eggs. 

 The mean winter production of all pure B.P.R. 9 9 in the 'Under 

 30' class is 15.61 eggs. The probable errors in both cases are less 

 than 1. Of course the 'Under 30' class in the case of B.P.R. 9 9 

 includes the following gametic types: LiU, LiLi, kk, and L2Z2. 

 The last two do not occur in the pure C.I.G. 's. Granting the great- 

 est conceivable influence to this, it is still evident that the Li factor 

 of a Barred Rock probably means a higher winter production than 

 the Li of a Cornish Game. But if this is true then plainly the 

 division or upper limiting point for the low fecundity class should 

 not be at 30 eggs but at some lower point in the case of females 

 bearing Li from a Cornish Indian Game source. If it be kept at 

 30 eggs for all birds, and there is a difference in the absolute fecun- 

 dity value of the factors, then plainly some birds will be put in the 

 low fecundity class, because of an 'Under 30' record, although 

 they really carry L2 and belong in the high fecundity class. Such 

 a state of affairs would account for just such discrepancies as 

 those observed in the matings under discussion. 



Matings of Cornish Indian Game males with Black and Barred Fi 

 females. Only one C.I.G. male was used in these F2 back-cross 

 matings. This was C.I.G. cf 578. As will presently appear, it is 

 to be regretted that other Game males were not used, because of 

 certain peculiarities arising in the results of some of these matings. 

 From pure Cornish and Fj matings d" 578 has been shown to have 

 the gametic constitution /Z]?2 • fkh- 



Male 578 was mated with 3 black Fi females indicated to be of 

 the typefLilo . FLik, with the following results: 



Matings: C.I.G. o" f Uh ■ f UU X Fi 9fLih ■ FLik. 



9 Progeny 



Winter Production: Over 30 Under 30 Zero 



Observed 1 9 1 



Expected 11 



Mean winter production 41 eggs 9.67 eggs eggs 



