Heredity of Race-Characters in Silkworm (Bombyx mort) 757 
Thus, Brood A furnished no bivoltin-producing but ten uni- 
volutin-producing mothers; Brood B furnished one bivoltin-pro- 
ducing and nine univoltin-producing mothers; Broods C and D 
each furnished two bivoltin- and eight univoltin-producing mothers; 
Brood E furnished three bivoltin-producing and seven univoltin- 
producing mothers; Broods F and G furnished four bivoltin- 
producing and six univoltin-producing mothers; Brood H fur- 
nished eight bivoltin-producing and two univoltin-producing 
mothers. The maximum number of bivoltin-producing mothers 
from a single brood in this group 1s eight, and from this the 
number grades down to zero. And yet, as previously stated, in 
Series E, Table III, in this series as a whole, the ratio of univolts 
to bivolts isasQq:1. This high proportion of univolts comes from 
the fact that there were many more broods furnishing univolts 
only, than bivolts, taking the series throughout as a whole. 
Diagram 2 shows the comparative number of univoltin and 
bivoltin broods in the second group of broods from which ten 
‘ndividuals were selected as mothers (Series H, I and J). 
0 
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Diagram2. Showing distribution of univoltin- and bivoltin-producing mothers in each of eight broods 
Thus Brood A furnished no bivoltin-producing but ten uni- 
voltin-producing mothers; Brood B furnished one bivoltin-pro- 
ducing and nine univoltin-producing mothers; Broods C and D 
each furnished two bivoltin-producing and eight univoltin-produc- 
