K. TOYAMA 



375 



TABLE V. 



( 5 Normal x (J Grey). 



Totals 



24 



24 



48 Totals 



28 



4.5 19 



92 



Grey series 



Grey series 



In the uext generation paired inte7' se, both series again yielded 

 only normal-egged F^ batches, the number of batches produced in the 

 former series being 66 and in the latter 123. Now it is quite certain 

 that in these matings there is no grey factor which has lain dormant as 

 in the former matings. 



The facts obtained in these three series of experiments and those 

 from the second series of the line breeding suggest to us, firstly that 

 among the eggs of grey-batch No. 24, there are two kinds of grey eggs, 

 one having the grey factor in its zygotic composition, while another has 

 no grey factor, in spite of its being grey in colour ; that is to say, some 

 grey eggs are heterozygous for the normal factor, some homozygous 



