FOOD AS A FACTOR IN THE DETERMINATION OF SEX. 



43 



experiments which have been planned in the hope that it may be 

 possible to show whether external factors such as temperature, 

 nutrition, time of fertilization, etc., have any influence in determin- 

 ing sex in Bufo. Recent investigations on other forms have 



— M 



- M 



Fig. I. Camera drawing of the genital organs of a male toad killed soon after 

 matamorphosis. 7\ testis;' B, Bidder's organ; C, corpus adiposum ; M, kidneys. 



Fig. 2. Camera drawing of the genital organs of a female toad killed soon after 

 metamorphosis. 0, ovary. Other lettering as in Fig. I. 



seemed to indicate that sex is not influenced by external condi- 

 tions, but that it is determined either before or during the fertiliza- 

 tion of the egg. If this is indeed the case, experiments such as 

 those that I have in mind will yield only negative results. But if it 

 can be shown for even one form that external factors may be 

 disregarded in considering the question of sex determination, 

 something will have been gained towards an ultimate solution of 

 the problem. 



Method. 



In endeavoring to ascertain the part played by any one factor 

 in sex determination, it is, of course, absolutely necessary that 

 the influence of all other factors shall be eliminated as far as pos- 

 sible. In making the experiments recorded in the present paper, 



