326 HELEN DEAN KING 
or in which the tadpoles were exposed to unusual conditions of 
temperature or of nutrition during the course of their develop- 
ment, although in many such eases the sex ratios obtained were 
very similar to those of control lots. 
In the various lots of individuals whose sex data are included 
in table 2 the number of males to each 100 females varies from 
75.92 to 114.10; when the percentages of females are compared 
there is found to be a difference of 10.43 points between the 
extremes of the series. These figures indicate that normally there 
is but little variation in the proportion of the sexes in different 
lots of toads. Table 2 shows also that there is no marked seasonal 
variation in the sex ratio of Bufo, such as Pfliiger (’82) and von 
Griesheim (’81) claim is the case with frogs. The latter investi- 
gators based their conclusions on the sex ratios in adult frogs col- 
lected from different localities in different years. My investi- 
gations have been confined entirely to the sex ratios in young toads 
that have recently completed their metamorphosis. Judging 
from the proportion of the sexes in several hundred adult toads 
that I have collected at various times during the past ten years, 
the sex ratio in adult individuals is very different from that in 
the young, since among adults there appears to be a considerable 
excess of males which is particularly noticeable during the breed- 
Ing season. 
The sex ratios in the two lots of individuals derived from eggs 
that were subjected to the action of sugar solution before fertil- 
ization fall within the limits of normal variation in the sex ratio 
(table 2). There is, therefore, some ground for an assumption 
that these cases afford no evidence that the normal proportion of 
the sexes was altered by the treatment which the unfertilized eggs 
received. The sex ratio found in the individuals that developed 
from eggs that were treated with salt solution is considerably 
lower than that in any control lot so far examined; but this may, 
perhaps, be considered as an exceptional variation. If these 
sex ratios are mere chance deviations from the normal, it certainly 
seems very remarkable that all three of them should show such 
a high percentage of females. 
