STUDIES IN THE EXPERIMENTAfi ANALYSIS OF SEX. 591 
very large body of facts bearing upon the question, but they 
have chiefly served to emphasise the irreg’ularity of the 
phenomenon, and it is certainly impossible at present to 
formulate any definite theory to connect the known facts in 
a comprehensive and satisfactory manner. It is not the 
purpose of this essay to attempt a review of the recorded 
cases of so-called hermaphroditism and of the abnormal 
condition of tlie sexual system which throw a somewliat fitful 
light on the problem, but reference may be made to the 
critical work of Herbst ('Formative Reize’ [H]), in wliich he 
discusses a large body of conflicting evidence and draws 
certain wide conclusions. He shows that, while the evidence 
in favour of some causal correlation existing between the 
primary and secondary sexual characters is oversvhelming, 
yet this correlation is not of so definite a nature as to sanction 
the simple view that the development of tlie secondary 
sexual characters as a whole is directly dependent on the 
development of the primai-y characters ; he concludes, how- 
ever, definitely, that in the vast majority of cases the full 
development of the secondary sexual characters in either 
sex is conditioned by the presence of the corresponding 
primary organ in a functional state. Even this very cautious 
and limited acceptance of correlation breaks down in certain 
exceptional cases. Thus Kellogg (12) has .shown that the 
gonad of the silkworm can be extirpated in the larval stage, so 
that no trace of this organ is to be found in the adult, and yet 
the moth develops its marked secondary sexual characters to 
the full, while Meisenheimer (13) has performed the ingenious 
experiment of transplanting the young gonad from one sex 
into the other where it may develop to maturity, and yet no 
change is to be observed in the secondary sexual characters 
of the adult insect. In the case of those particular insects, 
therefore, it appears that there is no connection whatever 
between the development of the secondary sexual characters 
and the presence of a differentiated gonad, and though it is 
true that this is the only case known in which this entire 
independence is to be observed, yet we can trace a series of 
