334 HELEN DEAN KING 
TABLE 5 
Eggs fertilized out of water 
| TOTAL | NUMBER | | PER CENT “hase NUMBER MALES 
SERIES ENE WANS SHS eer MALES | FEMALES | PPMALES | 100 TO 100 FEMALES 
| DIVIDUALS | TAINED | | | FEMALES (CONTROL LOT) 
{ 
=e | = Sea ijn 
A 400@ | 381 \) 106 —|) 275 | 72033 93aI54. || 110245 
B | 400; |). 374 ~)| 05/80; 2890 Gea | 
| 29-41) 114 10 
In none of the experiments that have been made with the eggs 
of Bufo in order to study the problem of sex-determination have 
the sex ratios obtained been any where near as low as those indi- 
cated in table 5. These results cannot be ascribed to an error in 
distinguishing the sexes, since the gonads in all of the individuals 
that were killed three weeks after they had completed their 
metamorphosis were well differentiated and the sex of the few 
individuals that died during metamorphosis was shown unmis- 
takably by sections. 
It is evident that whatever part selective mortality may have 
had in producing the unusual sex ratios obtained in various former 
experiments, it cannot be held responsible for these last results. 
Had all of the individuals in which sex was not ascertained been 
males, which of course is very improbable, the resultant sex 
ratios would still be very much lower than any of those indicated 
in table 2. The individuals in series A would contain 45.45 males 
to 100 females; while among the individuals belonging to series B 
there would be 38.40 males to 100 females: no control lot of indi- 
viduals so far examined has given a sex ratio of less than 81 males 
to 100 females. 
In these experiments the eggs were not subjected to the action 
of any chemical substance, but were merely kept out of water for 
some hours after their fertilization. It is evident, therefore, that 
the only change that could have been produced in the eggs was a 
diminution in their water content during the.early stages of their 
development. The eggs probably lost but little water from evap- 
oration during the fertilization period, as they were kept in a 
moist atmosphere in a closed vessel; but normally, as shown by the 
investigations of Bialaszewiez (’08), amphibian eggs absorb a 
considerable amount of water before the appearance of the first 
