SEX-DETERMINATION IN: AMPHIBIANS 323 
loss was due, in great part, to an accidental contamination of the 
water in two of the dishes containing the tadpoles and not to the 
treatment that the eggs received at the time that they were ready 
for fertilization. The lot of toads carried through metamorphosis 
gave a percentage of females nearly 10 points above that in the 
control for the series, and slightly greater than that found among 
the individuals belonging to the corresponding experiment in 
series A (table 1). 
Owing to the fact that solutions of NaCl are much more 
injurious to the eggs of Bufo than are sugar solutions, the ex- 
periment in which eggs from female b were immersed for twenty 
TABLE 1 
Eggs treated with hypertonic solutions before fertilization 
| 
iB om ‘. & fe 4 
SERIES SOLUTION USED < A a oe Z is A iy 
| § aS ERS a of as 
z a a a a x ua Bs 
a o* ee < B a Be 
>] a a a | ps as an 
min. | 
A 2 percent sugar | 10 300 279 | 131 | 148 03.04 | 88.51 
A 2 per cent salt 10 200 176 70 =| 106 60.34 66.03 
B 2percentsugar | 20 250 =| 194 86 | 108 55.66 | 79.62 
A | Control 350 | 322 | 169 | 153 | 47.50 | 110.45 
B | Control 350 334 | 178 | 156 46.40 114.10 
minutes in a 2 per cent solution of NaCl before fertilization 
was a failure. Only a few of the eggs segmented, and as all but 
twelve of the embryos died during gastrulation the experiment 
had to be abandoned. 
In each of the experiments outlined above there was found 
among the individuals carried through to metamorphosis a per- 
centage of females considerably above that in the control lot. 
These results accord well with those obtained in former experi- 
ments with hypertonic solutions (King, 711), although the per- 
centages of females are somewhat lower, owing possibly to the 
fact that the eggs were treated with weaker solutions. 
