STUDIES ON SEX-DETERMINATION IN AMPHIBIANS. 217 



continue their development. The female that had deposited 

 the eggs was killed and her remaining eggs were used for the 

 temperature experiments summarized in Table II. of a previous 

 paper (King, '10). Many of the eggs "fertilized dry" died 

 during the gastrulation period, and only 44 individuals lived until 

 it was possible to ascertain their sex. Of these 44 individuals 

 17 were males and 27, or 61.36 per cent, were females. The lot 

 of eggs from the same female that serves as a control for this 

 experiment, since they were fertilized with sperm from the same 

 male, produced 51.39 per cent, of females. 



The outcome of this single experiment has little significance, 

 as the number of individuals in which sex was ascertained is too 

 small to give results of value, especially as it is not known how 

 long the eggs had been laid and fertilized before they were found 

 and placed in water. From the condition of the eggs when they 

 were discovered it was evident that they had been laid at least 

 three hours. The possibility of obtaining normal tadpoles from 

 eggs that had been fertilized out of water having been demon- 

 strated by this experiment, a further series of experiments was 

 made this past spring in the following way: Strings of ripe eggs 

 were removed from the uterus of a female and spread out in an 

 empty glass dish. Then, by means of a pipette, a few cubic 

 centimeters of a concentrated solution of spermatozoa were dis- 

 tributed drop by drop over the eggs in as uniform a manner as 

 possible. The dish was then covered with a glass plate and set 

 aside. Four hours later part of the eggs (lot X) were placed 

 in water. An examination of the eggs at his time showed that 

 many of them had segmented in an apparently normal manner 

 and were already in the 4-8 cell stage of development. The 

 remaining eggs (lot Y) were transferred into fresh water at the 

 end of seven hours, when a considerable number of them were in 

 the 32 cell stage. A number of eggs in both lots failed to seg- 

 ment, possibly because the lack of water prevented the free move- 

 ment of the spermatozoa. 



In these experiments the loss of water from the eggs as a result 

 of evaporation was probably very slight, since the thick jelly- 

 like substance surrounding the eggs would serve to protect them 

 during the time that they were kept out of water. The condi- 



