398 



Maternal Liherltance 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 crosses, as we have already seen, certain matings gave no 

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

 mentioned below : 



iV^== normal-egged batch; G = grey-egged batch; 2?G = 7j-grey. 



(1) (2) 



(?iVx ,f G) (?iVx cTG) 



I I 



Fi eggs iV AT 



Fi eggs 

 Fz eggs 

 Fi eggs 

 -^6 eggs 

 F6 eggs 



N (N ^ G) 



N 



N (G + BG) 



r~ 



—\ r 



{N + G + BG) 



i 



I 



.V (A^ + G + BG) {G + BG) (G + BG) {N + G + BG) N 



r ^1 I— 1 



(G + BG) {N + G + BG) (G -f- BG) 



N 



r- 

 I 



+ 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 ( $ DR X f^'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==(DR + RR). 



2. % RRx^ RR = F^R eggs = {RR). 



jPj 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 



