88 
Scientific Proceedings (43). 
the right or from the left testicle of three different males, all 
gave practically normal sex ratios as the proportion of females 
ranged from 46.92 per cent, to 55.64 per cent. 
Three batches of eggs from two different females were fertilized 
out of water and kept in a moist chamber for several hours. Each 
batch of eggs gave an unusual excess of females, the proportion of 
females varying from 60.86 to 70.83 per cent. 
Mature eggs from another female were subjected to the action 
of a 2.5 per cent, solution of salt or of cane sugar for ten minutes 
and then fertilized in tap water. In each case 70 per cent, of 
females was obtained. In this series of experiments, as well as 
in the preceding one, it is probable that the eggs lost water during 
the fertilization period or at least were prevented from absorbing 
water during this time. 
Seven lots of eggs from four different females were fertilized 
in solutions of hydrochloric or of acetic acid, the strength of the 
solutions varying from .01 per cent, to .0025 per cent. In every 
instance the percentage of females obtained was from 10 to 20 
per cent, lower than that which is probably normal for the species. 
Lots of eggs from the same females fertilized in alkaline solutions 
(NH4OH or NaOH) of the same strength gave proportions of the 
sexes within the range of probable normal variations in the sex 
ratios of different lots of individuals. It is probable that the 
acid solutions caused the eggs to absorb an extra amount of water 
during the fertilization period. The alkaline solutions were ap- 
parently too weak to have any influence on the eggs. 
No definite conclusions can be drawn from these experiments, 
since in every case the mortality was very great. The results 
strongly suggest, however, that in the toad, Bufo lentiginosus, 
sex is determined at or near the time of fertilization and that it 
can be influenced by external factors. They also seem to indicate 
that the relative amount of water in the egg at the time of fertili- 
zation has some influence in determining sex: an increase in the 
water content tending to produce a male; a lowering of the water 
content favoring the development of a female. 
