STUDIES ON SEX-DETERMINATION IN AMPHIBIANS. 209 



permeable to the lower alcohols and are not greatly injured by 

 them, the idea was suggested that it might be possible to fertilize 

 the eggs of Bufo in solutions of alcohol that would be strong 

 enough to enter the eggs and, by combining with the fats, bring 

 about an alteration in the cell structure that would later manifest 

 itself in a change in the normal sex ratio. Batches of eggs from 

 the same female were therefore placed with sperm from the same 

 male in alcohol solutions of the following strengths: 10, 5, 2, I, 

 .5, .25, .13 per cent. In each case the eggs remained in the 

 solution for one half hour and were then transferred into fresh 

 water where they continued their development. 



None of the eggs that were subjected to the action of the 10 

 per cent, and the 5 per cent, alcohol segmented. This result can 

 probably be attributed to the injurious effects of the solutions 

 on the spermatozoa which were thus rendered incapable of ferti- 

 lizing the eggs. Overton ('02) has shown that a 5 per cent, solu- 

 tion of alcohol anaesthetizes muscle, and presumably a solution 

 of this strength would have the same effect on the spermatozoa 

 of Bufo; no investigation of this point was made. At least 

 one half of the eggs that were fertilized in the 2 per cent, and in 

 the I per cent, solutions of alcohol segmented normally and con- 

 tinued their development: in the remaining series practically 

 all the eggs were fertilized. 



Table I. shows the results obtained in this series of investi- 

 gations. 



TABLE I. 



EGGS FERTILIZED IN SOLUTIONS OF ALCOHOL. 



The sex ratios obtained in this series are very uniform, since 

 in no case is there a deviation of even five from the percentage 

 of females found in the control lot. Somewhat lower percentages 

 of females were found among the individuals that had developed 



