No. 611] 



ALLELOMORPHS 



homozygotic (AA) spikelets in any part ''x" of the total 

 number of spikelets which is taken as a unit, and again 

 that in the remaining (1 — x) part of the total number of 

 spikelets, the other type of reversion will occur, turning 

 some part "y" of the whole generative tissue taken as a 

 unit from the Aa state to the AA state. For simplicity, 

 however, we may substitute ''x" for *'y" in the above re- 

 lation, because it seems presumable that a similar prob- 

 ability of reversion may exist constantly all through the 

 ])lant life. Such a plant will have the following consti- 

 tution in regard to the generative tissue: 



x(AA) + (1 - X) [x(AA) -f (1 - X) ( Aa) ]. 

 As the result of self-pollination, the progeny of such a 

 parent plant will show the constitution : 



x(AA) + (1 - x) 11(1 + x)2(AA) + i (1 - x^) (Aa) 

 + i(l-x)Maa)]. 

 Applying arbitrary values to "x" in this formula, we 

 shall get numerical relations among segregates. In 

 Table V the results of such calculation are compared with 

 results obtained by the experiments in 1913-1915. Thus 

 we may find the average partial homozygosity of hetero- 

 zygotes around 4 to 6 per cent., the average partial fer- 

 tility of sterile plants being, as was already shown, ca. 

 4 per cent. 



TABLE V 

 Calculations on Data of Table TV 



Percent age 78.96^ 21.0 4% 4 1.05% | 58.95% 



It has also been noticed that the sterility concerned is 

 associated with an abnormality represented by the be- 

 havior of chlorophyll at the ripening of seeds. While, at 

 tlie ripening season, the chlorophyll in the fertile sections 

 of the mosaic forms turns to yellow just as in ordinary 

 fertile plants, the chlorophyll in the sterile sections still 



