394 Maternal Inheritance and Mendelism 



Thus the Ft eggs laid by the moths of the dominant series will be 

 all D in certain lineages while in others they will be a mixture of both 

 D and R batches in different proportions. 



In like manner, F^ moths derived from the F^ R batches which 

 consist of (1) DR, (2) {DR + RR), and (3) RR batches, when inbred 

 will produce the following F^ eggs: 



Zygotic composition Outward appearance 



Mating " of egg-batches of egg -batch 



1, DR inter se ^ DR x s DR = {DD + 2DR + RR) D 



2. {DR + RR) inter se . 



9 DR X. s DR-{DD + DR + RR) D 



9 DR X ,i RR = {DR + RR) D 



9RR X d DR^(DR + RR) R 



9RR X g RR = RR R 



3. RR inter se 9 R x s R =RR R 



The Fi eggs laid by the moths derived from F3 R eggs will be all 

 D batches in certain lineages, while there will be a mixture of D and 

 R batches in some other lineages, and all R batches in the remainder. 



If we continually eliminate the lineage which produced the an- 

 tagonistic characterized batches in this way in both series, each of them 

 may be established as a constant or homozygous form. In the dominant 

 series, the lineages which give all F4 D batches are three, namely : 

 No. 1 or DD series. No. 2 or {DD + DR) and No. 3 or DR. If they are 

 inbred. Series No. 3 would give mixed F^ batches which are to be 

 discarded from the dominant series, while the other two would give all 

 Ff, D batches. In F^, those from No. 2 will disintegrate into their 

 components, D and R, and those which produced all F^ D batches will 

 be the descendants of Series No. 1, or a lineage DD, which is a homo- 

 zygous dominant from their first appearance. 



To extract a homozygous dominant form from these series of crosses 

 the elimination of six consecutive generations will be required, except 

 when we luckily happen to pick out the lineage of DD series, in which 

 case we are able to get it in a constant form in a much less number of 

 generations. 



In the recessive series, however, if we select the lineage which 

 produced all R batches in Fi, the R form is easily established as 

 a constant form, since the zygotic composition of this series is RR. 



This is what we might expect to find according to Mendelian 

 principles if the characteristic behaved as maternal in inheritance. If 

 the D form consists of two or more factors, disintegration of factors will 



