760 Isabel McCracken 
Certainly, however, with the characters under present con- 
sideration it is not until the second generation at least that the 
results of the cross univolt +bivolt are brought to full expression. 
However, as indicated in Series K (Table IV) it may take four 
generations. While the zygotes in Series A (Table I) are pre- 
disposed to the expression of the character of the univoltin race, 
the reappearance of bivoltinism through the univoltin line in succes- 
sive series (Series A’, Series E, Table III and Series K, Table 
IV) to a very appreciable degree, shows that expression is in no 
wise du: to absence of the alternative or bivoltin character. 
This character is, on the contrary, simply held in abeyance and 
transmitted from generation to generation through the germ 
cells without expression. Hence transmission of this character 
has no relation to expression or as Cook puts it® “the failure of a 
character to secure expression does not indicate that it has failed 
of transmission.” They are “independent and separate processes.” 
This brings us to a consideration of potency. “Touse Cook’s 
synonym “characters which secure stronger or more general expres- 
sion in the new gametes are called prepotent, those which tend to 
decline or ape may be called sub-potent, ave characters 
which secure an unmodified representation in behalf of the 
gametes may be called equipotent. 
From a consideration of the data at hand, it is evident that 
potency is a phenomenon of a fluctuating nature. Univoltinism 
is at first, and for a series of years prepotent, becoming less and 
less so as the generations advance whether or not bivoltinism 
‘has found expression in the interim—note Series E (Table II1),— 
88 per cent, and Series K (Table IV), 74 per cent; Series G, 
Table III, 69 per cent, and Series J, Table IV, 50 per cent.’ 
Or what is more striking, compare the various broods in Diagram 
2. In Brood A, univoltinism is totally prepotent,in Broods B, 
C, D, E, F, G, and H, it is partially prepotent and bivoltinism 
is subpotent; in Brood J, bivoltinism is partially prepotent and 
© Lochetit., p. 259, 
7Note added September 20, 1909. The bivoltins of this series were reared in the spring of 
1909. Thirty-four matings were then made within the series, which resulted in 67% Bi. and 32% 
U. Thus the bivoltin in this series has passed over from a sub-potent to a pre-potent condition. 
