Heredity of Race-Characters in Silkworm (Bombyx mori) 751 
Thus it is that in the first generation, through a bivoltin male 
(and pure univoltin female), bivoltinism failed of expression and 
in the second generation through a hybrid uni(bi)voltin male 
(and pure univoltin female), (Series A), bivoltinism again failed 
of expression; while in the second generation through a hybrid 
uni(bi)voltin female, bivoltinism reappeared through some mothers 
and failed through others whether or not these had hybrid mates 
(Series B and C). It seems also that there is an equal chance for 
the reappearance of the bivoltin condition through the female 
uni(bi)hybrid whether she has a uni(bi)hybrid mate or a pure 
univoltin mate. In other words, the condition of the brood with 
reference to the character in question is due to the condition 
or potency of the mother regardless of the condition of her mate, 
but inherited it may be through her male ancestor and may there- 
fore be interpreted as a purely maternal though racial character. 
The question now arises, is the race-character of the 1904 male 
parent lost completely from the lineage of the 24 male offspring 
forming the male parents in Series A and from the four broods 
in Series B and C, or is it simply rendered inactive. Further 
results show the latter to be the case. 
The six broods of Series B and C, bivolting in 1905, were 
reared in the summer of 1905 and many matings made for the 
spring rearing of 1906. During a certain exigency in the spring 
of 1906, all but 12 broods, the offspring of broods in Series B, 
were abandoned. These 12 broods with 12 broods from the 
spring lot of 1995 that failed to bivolt (Series A), were reared 
in the spring of 1906. Thirty matings were made in each of 
these series. Series D is made up of matings within the bivoltins 
of Series B, i. e., spring matings of moths from the summer bivol- 
tins of 1905, whose parents were hybrid uni(bi)voltin, that had 
failed to bivolt in 1904, (hence — 04 +05). Series A’ is made 
up of matings of moths within 1906 broods, that had failed to 
bivolt in 1905 whose male parent was a hybrid uni(bi)voltin 
and whose female parent was a pure univoltin, (hence —04 —05). 
Of the 30 matings in Series D, four broods hatched in the summer 
of 1906, that is, were bivoltins, the rest of the series having entered 
into univoltin condition. A ratio of 6.5 U:1 B or 86 per cent 
