400 INTERNAL SECRETIONS 



processes of transformation caused by a factor common 

 for both ? Champy considers it possible to state merely that 

 the first change on the part of the gonocytes towards sexual 

 differentiation is correlated with development of certain sex 

 characters, and that he is unable to say what the nature of 

 this correlation is, or whether the first change has any direct 

 influence on the second. 



5. Insects. Goldschmidt's Experiments. 



Intersexuality is very widespread in insects, and in this 

 group also there is a great variability in the different 

 degrees or types of intersexuality. 



It seems at first thought impossible to postulate an hormonic 

 basis of intersexuality in insects, as no hormonic dependence 

 of the sex characters upon the sex gland appears to exist in 

 this class. Intersexuality cannot be experimentally induced 

 in insects by gonadal transplantation, though the engrafted 

 gonads '' take " easily. 



On the other hand, intersexuahty in insects can be experi- 

 mentally controlled, as Goldschmidt has shown in his 

 experiments on the gipsy moth. We shall deal here with 

 Goldschmidt' s (1917-22) work only in so far as certain general 

 points are involved. 



By crossing definite races of gipsy moths with one another 

 Goldschmidt failed to obtain the expected normal numerical 

 sex ratio, some of the "would-be-males" or of the "would-be- 

 females" being intergrades between normal males and females. 

 Goldschmidt stated that the number of intergrades or inter- 

 sexual individuals, and the degree of intersexuality, i.e., the 

 degree of transformation of one sex into the other, is constant 

 for a given cross of races. There is also for every cross a 

 constancy as to the time at which the transformation takes 

 place. The degree of intersexuality is the more pronounced, 

 the sooner the heterosexual transformation sets in during onto- 

 genetic development. The behaviour of the individual parts 

 of the body of an animal undergoing heterosexual transforma- 

 tion is very different. Those organs which differentiate very 

 early during embryonic development rarely undergo hetero- 

 sexual transformation, whereas those organs which differentiate 

 later show a great tendency to heterosexual transformation. 

 The first-mentioned organs, for instance the gonads, will be 



