STUDIES ON SEX-DETERMINATION IN AMPHIBIANS. 



225 



ized in acid solutions the percentage of females falls to 40.84 

 per cent. Between the extremes of the series there is a difference 

 of 31.68 per cent. These variations in the sex ratios are uniform 

 in the different series: they are apparently beyond the limits of 

 normal variations in the sex ratio of Bufo, and they are too large 

 to be justly attributed to mere chance variations in the sex 

 ratios of different lots of individuals. 



The percentages of females obtained in the series of experi- 

 ments in which eggs were fertilized in solutions of sodium hydrate 

 are indicated in Table VII. 



TABLE VII. 

 EGGS FERTILIZED IN SOLUTIONS OF SODIUM HYDRATE. 



In this series the apparent effect produced on the sex ratio by 

 fertilizing eggs in alkaline solutions is the reverse of that which 

 seemingly results when eggs are fertilized in acid solutions, since 

 in each case a percentage of females is found which is somewhat 

 above that in the control lot. The percentages of females ob- 

 tained show very much less deviation from those of the control 

 than was the case in the acid series; and in no lot is the proportion 

 of females more than 6 per cent, above that of the control. It 

 seems probable, therefore, that these percentages, although some- 

 what high, have no especial significance, and that they are chance 

 variations in the sex ratio. 



The great difference between the results obtained when eggs of 

 Bufo are fertilized in acid solutions and those found when eggs 

 are fertilized in solutions of sodium hydrate would seem to 

 indicate that these solutions have no effect whatever on the 

 sex-determining process, since both solutions would presumably 

 affect the eggs in the same way and tend to cause them to absorb 



