Bo HELEN DEAN KING 
solution of sugar; in each case the eggs remained in the solution 
for one hour before being transferred into tap water. These 
eggs reacted very differently from those that were fertilized in 
acid solutions (table 3), although they were taken from the same 
female and fertilized with sperm from the same male. In neither 
lot was the mortality at the time of fertilization greater than 1 
per cent, and only a small number of tadpoles died in the early 
stages of their development. As shown in table 4, the sex ratio 
in the individuals that were carried through to metamorphosis 
was in each instance practically the same as that in the control 
for the series. These results indicate unmistakably that the 
solutions in which the eggs were fertilized had no effect on the 
sex of the tadpoles, although they continued to act on the zygote 
for nearly an hour. 
As indicated in table 4, the results obtained in these experiments 
offer no evidence that the sex ratio in Bufo can be altered by 
fertilizing the eggs in hypertonic solutions. This negative result 
may, possibly, be due to the fact that it is not possible to fertilize 
the eggs in hypertonic solutions that are strong enough to pro- 
duce any appreciable change in the osmotic pressure. 
Keeping eggs out of water for some time after their fertilization 
was another means employed to cause the zygote to lose water, 
or at least to prevent its absorption of water, during the early 
stages of development. This method of experimentation has the 
very great merit that the eggs are not subjected to the action of 
any chemical substance that might possibly produce changes in 
them that would lead to abnormal development and to the early 
death of the embryos. 
The technique employed in the two experiments that were 
made this year was as follows: On their removal from the uterus 
of the female the eggs were placed on filter paper and a few drops 
of water containing spermatozoa were distributed over them with 
a pipette in as uniform a manner as possible. The excess of water 
was then quickly drained off, and the eggs were transferred into 
a moist chamber where they remained for a number of hours be- 
fore they were allowed to continue their development in water. 
With very few exceptions all of the eggs from female a that were 
experimented upon were fertilized, and they began segmenting 
