84 NATIONAL TRENDS IN BIOLOGY 



eggs of toads. She kept them away from water, however. 

 These eggs, therefore, contained very little water before 

 fertilization and a predominance of females resulted from 

 her experiments. (4) Goldschmidt came to the conclusion 

 that certain substances in the fertilized ovum produce the 

 two sexes, and that these substances influence the rate 

 of metabolism. He calls the substance which produces 

 maleness Andrase, and that which produces femaleness, 

 Gynase. Goldschmidt's principal experiments consisted in 

 crossing German and Japanese races of moths. Sometimes 

 he got males and sometimes all females. At other times, 

 he was able to obtain all intermediary stages; this, of 

 course, refers only to so-called secondary sexual char- 

 acteristics. 



One may summarize the differences between the chro- 

 mosome theory and the metabolic theory thus: 



Chromosome Theory Metabolic Theory 



Sex is determined at fertili- Sex is determined at an 



zation. early stage in the em- 



Sex is fixed. bryo. 



Cause of sex lies in the Sex can be modified. 



chromosome mechanism. Cause of sex lies in the 



metabolic rate. 



If I understand Goldschmidt correctly, he holds that 

 in the fertilized egg, after maturation, determiners are 

 always present in the chromosomes for both characters, 

 maleness and femaleness, blackness and whiteness, or 

 whatever the opposing characters from the two parents 



