STUDIES IN THE EXPERIMENTAL ANALYSIS OF SEX. 581 
sexual characters, and under certain conditions might even 
develop typical ova in their testes, the infected females, on 
the other hand, although the ovaries in many cases completely 
disappeared, never approached to the male primary or secondary 
sexual characters in the slightest degree. After citing and 
examining other cases, especially among the Crustacea, in 
which the male sex showed undoubted signs of latent herma- 
phroditism, I concluded that, at any rate in these forms, it 
would appear that the male was a potential hermaphrodite, 
and the female purely female. The significant bearing of 
this conclusion upon a Mendelian theory of sex was obvious, 
and since at the time the only definitely formulated Mendelian 
theory of sex was that of Castle, according to which both 
sexes of any species were potentially hermaphrodite, I was 
led to formulate an alternative theory, which did not require 
the assumption of selective fertilisation, in the following’ 
words : “ There is a final topic for discussion, namely, the 
connection between the theory of sex here adopted and con- 
temporary l\Iendelian theory. It is interesting to observe 
that where an attempt has been successfully made to find 
structural differences in the germ-cells as possible indications 
of this early sexual diffei’entiation, the manner of this differen- 
tiation is in harmony with the results we have obtained from 
the study of parasitic castration. The discoveries of Henking, 
McClung, Wilson and others have shown that in many insects 
two kinds of spermatozoa exist, differing in the constitution 
of their chromosomes, while the eggs are apparently^ all the 
same. If we suppose that the two kinds of spermatozoa 
represent the male and female sex respectively, while the 
eggs are purely female, we ’would obtain in the process of 
sexual generation ^ c? ? + h ? ? , in which the male 
spermatozoa united with female eggs give rise to males of 
really hermaphrodite constitution, while the female sperma- 
tozoa united with female eggs give rise to females of pui’e 
female constitution. It is obvious that this interpretation is 
in strict agreement with the main conclusion brought out in 
this chapter, viz. that males are potentially’ hermaphrodites. 
