398 



Maternal Inheritance and Mendelisni 



By similar reasoning, we can explain the results obtained by 

 crosses between males of the grey variant No. 24 and females of the 

 normal-egged breed. 



In these crosse.s, as we have already seen, certain matings gave no 

 grey eggs, while some gave both normal and grey batches in the order 

 mentioned below : 



J^ = noimal-egge(l batch; G = grey-egged batch; 73G = /J-grey. 

 (1) 



h\ eggs 



F, eggs 



Fi eggs 



■' 4 ^oo'^ 



•f's eggs 



Fa eggs 



( ? A' X <? G) 



I 

 A' 



I 



I — 

 I 



N 



i 



N 



(N + G) 



j _J 



! r 



.V (G + BG) 



(2) 

 {^ Nx ^G) 



I 



N 



N 



I 

 {N + G + BG) 



N 



I II I I 



(N + G + BG) (G + BG) (G + BG) (N + G + BG) N 



(G + BG) 



I 



I ' : 



I I 



N (G + BG) 



I I I 



(lY + G + BG) (G + BG) 



Before attempting to explain this result it will be necessary to note 

 here that the grey variant No. 24 was picked out from certain normal- 

 egged breeds in which a few batches of this variant sometimes appear, 

 and consequently it is proper to consider it to be a heterozygous form. 

 Let us suppose that the grey No. 24 batch is derived from such matings 

 as ( $ DK X ^RR), which give all D eggs. In this case the constitution 

 of the egg batch D will be (DR + RR). If normal-egged females 

 which are recessive to the grey were mated with males derived from 

 this D batch, the following gametic combinations will be expected : — 



1. ^ RRx^ DR = F,Reggs = iDR+RR). 



2. ^ RRx^ RR = F,R eggs = (RR). 



Fi eggs laid by those matings are all R, but their zygotic constitutions 

 are different from each other, as we easily see from the formulae above 

 shewn. The resulting F^ eggs will, therefore, be in some matings (No. 1) 

 a mixture of D and R batches and in others (No. 2) all R. The lineage 



