Heredity of Race-Characters in Silkworm (Bombyx mori) 755 
(Table III), and Series J (Table IV), representing continuous 
selection of the hybrid bi(uni)voltin through four consecutive 
years (eight generations from the hybrid parent), we find again 
the univoltin continuously predominating from 1906 and a gradual 
decrease in the percentage of univolts until in 1908 the potency 
of the two characters seem to be equalized; thus, 40 per cent 
(1905),86 per cent (1906), 69 per cent (1907),50 per cent (1908).? 
These two groups of percentages show that there is some potent 
influence in the bivoltin as a character that counts for its accumu- 
lation from year to year whether it is expressed in the parents 
selected, as in B, D, G, and J, or has not been manifest in these, 
as in A, A’, E and K (see also “Table of Descent’). 
It is also strikingly noticeable that in the former group where 
selection was made continuously through the line in which the 
bivoltin character was expressed, the decrease in the percent- 
age of univolts (increase in percentage of bivolts) is much more 
rapid (with the exception of the unexplained low percentage of 
1905) than in the latter group where selection was through the 
line in which the character was not expressed. 
If we consider a third group of matings, Series D (Table I), 
Series F (Table III), and Series I or Series L (Table IV), we find 
the same consistent decrease in the percentage of univoltinism, 
86 per cent (1906), 80 per cent (1907), 70 per cent or 73 per cent 
(1908). 
It may be argued, and the argument might be a valid objection 
to results in all series except A, A’, E and H, that the number of 
matings made is too small for adequate results. But since in 
the series of smaller lots, the results are in general consistent 
with the results obtained in the larger lots we may, I think, con- 
sider that on the whole the small size of certain lots has’ not 
materially interfered with normal general results. If we base 
our conclusions on series A, A’, E, and K independently, or 
include all the series in our considerations, the results are the same. 
This g adual decrease of the percentage of univoltins seems 
traceable to one thing. The persistent predominance of the 
univolt appears to represent the pull or “drag” of univolt an- 
cestry, while its gradual decrease under each condition appears 
2And in 1909, 32 per cent, thus becoming sub-potent. 
