STUDIES ON SEX-DETERMINATION IN. AMPHIBIANS 
V. THE EFFECTS OF CHANGING THE WATER CONTENT OF THE EGG, 
AT OR BEFORE THE TIME OF FERTILIZATION, ON THE 
SEX RATIO OF BUFO LENTIGINOSUS 
HELEN DEAN KING 
From The Wistar Institute of Anatomy and Biology 
The investigations recorded in the present paper are a contin- 
uation of those that have been carried on for several years. past 
in an attempt to ascertain whether external factors can influence 
the determination of sex in the toad, Bufo lentiginosus. 
All of the experiments were made with the eggs from two 
females, a and b; the eggs from each female being fertilized with 
sperm from the same male. The individuals derived from the 
eggs of female a are considered to belong to the ‘series A’ group 
of experiments; while ‘series B’ refers collectively to the indi- 
viduals that developed from the eggs of female 6. It was not 
possible to note the exact number of eggs used in ‘any experi- 
ment, but an attempt was made to use approximately the same 
number of eggs in each case, and to estimate, as accurately as 
possible, the number of eggs that failed to develop. 
The apparatus that was used in rearing the tadpoles was de- 
scribed in detail in a previous paper (King, 711). As this appara- 
tus has its limits of capacity, it was not possible to use all of the 
embryos that developed from each lot of eggs. Definite numbers 
of individuals, forming in every case except the acid experiments 
at least 75 per cent of the total number of eggs that had been 
experimented upon, were taken at random as they emerged from 
their jelly like membrane three days after the experiments were 
begun. In the various tables in this paper the figures given in 
the column headed ‘total number of individuals’ refer, there- 
319 
THE JOURNAL OF EXPERIMENTAL ZOOLOGY, VOL. 12, NO. 3 
APRIL, 1912 
