20 



Tanaka. 



F2 normal whites and plain yellows were also not homogeneous 

 as to the genetic constitution, but 25 7o of them were heterozygous in 

 one of two allelomorphic pairs in question, and thus throwing off, if 

 bred among themselves, a number (25 "/u) of plain wliites, while the 

 majority (75 %) of F2 individuals were homozygous and bred true. The 

 possible ways of zygotic combination are put forth below. 



Fa normal whites inter se: 



F» Fs 



cf 



Zygotic 

 const. 



Gametic 

 series 



Zygotic 

 const. 



NyNij 



Gametic 

 series 



Ny 



1) NijNij Ny 



2) NyNy Ny Nyny 1 Ny -\- \ ny^ 



3) Nyny \ Ny -{- \ ny NyNy Ny \ 



4) Nyny 1 Ny -\- 1 ny Nyny 1 Ny -\- 1 ny 



F2 plain yellows inter se: 

 Fo 



all normal white 

 Class E. 



3 normal white 

 1 plain white 



Fs 



Class 

 F. 



Zygotic 

 const. 



1) nYnY 



2) nYnY 



3) nYny 



Gametic 

 series 



nY 



ny 



1 nY -\- I ny 



Zygotic 

 const. 



nYnY 

 nYny 

 nYnY 



Gametic 



series 



nY 



1 nY -\- 1 ny 

 nY 



all normal yellow 

 Class G. 



3 plain yellow 



Class H. 



4) yiYny 1 nY -\- I ny nYny 1 nY -\- \ ny 



I 1 plain white ) 



Thus occurrence of plain whites in the progeny of the normal 

 white (genealogical table I) is easily accounted for. 



The frequency of occurrence of each class in the offspring of the 

 normal yellow, the normal white and the plain yellow in the Class A 

 will be calculated as follows. 



a) Subsequent generation to the normal yellow of Class A^) \n 

 any generation further than F2. 



') The results of otlicr classes (B-H) are rather simple, therefore they are not 

 mentioned here. 



