) Heredity of Race-Characters in Silkworm (Bombyx mori) 759 
pure alternates. Accordingly, ten females, each from a brood 
that had proven its bivoltin-producing capacity, were mated 
with males of pure univoltin extraction. This is practicable 
because of the great difference in time of the issuance of moths 
from cocoons of the same brood. The eggs of each of these ten 
moths were bivoltin or maternal. 
There were also 35 matings made between pure univoltin 
females and males from broods that were known to be furnishing 
bivoltin-producing females. In this case also the eggs were all 
maternal or univoltin. 
Since all the sisters of known bivoltin-producers, produced 
bivoltins only, with pure univoltin mates, and since no pure 
univoltin female produced other than a univoltin brood even 
with a bivoltin mate, it is apparent that it is the condition of the 
gametes of the immediate female that determines the character 
of the brood, these gametes embodying a heritage from both 
grandparents. The character of the race of the immediate male 
mate may be transmitted but is not expressed. 
This lends support to Cook’s argument’ that the conjugation 
of gametes is not complete at the time of fertilization, complete 
fertilization taking place only when the “chromatin is fused in 
mitapsis, preceding the formation of cells for the next generation.”’ 
It is therefore this generation (“‘pergugate”’ of Cook) that will 
show the full effects of the previous fertilization, or “inheritance- 
relations” of the characters of the original parental organisms in 
Cook’s view. 
While with this particular group of characters there isa failure: 
of expression in each first generation (conjugate generation of 
Cook) this is not the case with larval nor cocoon color characters 
as previously noted. Here, plainly as pointed out, the first or 
conjugate generation partakes strongly of the nature of both 
parents. ‘Therefore it is, that expression or non-expression of 
character in the first generation must involve something aside 
from the fact that fertilization and conjugation as looked upon 
by Cook are separate entities. 
® Cool, O. F.: Mendelianism and other methods of descent. Proc. Wash. Acad. of Sci., ix, 1907, 
p- 192. 
