SEX-DETERMINATION IN AMPHIBIANS Boll 
continuing experiments of this kind it was considered necessary, 
therefore, to use very weak solutions in order that the mortality 
among the spermatozoa might be greatly reduced. 
One batch of about 400 eggs, taken from female a, was placed 
with spermatic fluid in a 4 per cent solution of cane sugar; an- 
other batch of eggs from the same female was fertilized in a 4 
per cent solution of NaCl. Each lot of eggs remained in the solu- 
tion for one-half hour and was then transferred into fresh water. 
The mortality at the time of fertilization was slightly greater 
where salt solution was used, but in this ease it was not more than 
10 per cent. Since a former study of the fertilization of the egg 
of Bufo (King, ’01) has shown that the egg is normally penetrated 
by the spermatozoan within three or four minutes after it has been 
deposited, it is evident that in these experiments the solutions 
acted chiefly on the zygote and not on the unfertilized egg. 
In each case 300 embryos were taken for rearing, and the greater 
number of these, as shown in table 4, were carried through to 
metamorphosis and their sex ascertained. Each lot gave a 
percentage of females higher than that in the control for the 
series, but well within the limits of normal variation in the per- 
centages of females as shown in table 2. It is doubtful, there- 
fore, if in either case the normal proportion of the sexes was altered 
by the treatment which the eggs received at the time that they 
were fertilized. 
One lot of eggs, taken from female 6, was fertilized in a + per 
cent solution of salt, and another lot was fertilized in a } per cent 
TABLE 4 
Eggs fertilized in hypertonic solutions 
1 1 n nm 
eas .\)2 fa | 38 | a8 
| i) BH wa | | a S < 5 
2) Qa< is) a | i Sy 
| 5 25 | ae | | ee ial Ses ZEO 
SERIES | SOLUTION USED <4 Bay) | i een) Bs = 
fe ZS < | ra] a | zS ate Es 
° en | e 5 | n e) So 3 AS a) a 
a ea! sa | & S| sees 30 S06 
a 5 =} | 50 a a Qs 5a bH~ 
a a | & fh a Cy Z a 
i — | | 
| min. | | | | | 
| | | | | PD x3 | 
A 2 per cent sugar 30 | 300 | 246 | 112 | 184 | 54.47) 83.58 110.45 
A | dper cent salt 30 300 | 272) 130| 142 | 52.20) 91.54! 
B | dpercent sugar 60 400 | 367 | 185) 182 | Hien 114.10 
B 7 per cent salt 60 450 | 391) 215 | 176 | 45.26)121.59| 
| | | | | | 
