A. D. Darbishire. 
328 
parallel between the mode of inheritance of the two sets of 
characters, and between the characters themselves is very close. 
Mendclian and sexual characters are both inherited in an alter¬ 
native manner, that is to say the offspring resemble one of their 
two parents to the exclusion of the other. The details of the 
similarity between the mode of inheritance of Mendelian and that 
of sexual characters do not concern us now. The point is that the 
two tilings are similar ; and that a theory of the mode of inheritance 
of Mendelian characters was in the field before a theory relating to 
sexual characters. So that the obvious fact of the close similarity 
between the two phenomena has given birth to the theory that 
sexual characters are Mendelian in their mode of inheritance. If a 
theory of the inheritance of sexual characters had been in the field 
first, this same fact would have resulted in the enunciation of a 
theory that the inheritance of Mendelian characters is similar to that 
of sexual characters. Of course the discovery of the mode of 
inheritance of sexual characters is a more interesting result than 
is that of Mendelian ones. So that the latter discovery would have 
received far less attention than the discovery of the mode of 
inheritance (assuming for the sake of the argument that it has 
been discovered) of sexual characters has done. I lay emphasis on 
this point in order to show that the explanation of a phenomenon 
(such as sex in this instance) is nothing more than a description of 
it in terms of a theory which happened to be in the field before it. 
The first organized attempt to demonstrate the Mendelian 
inheritance of sexual characters is that of Castle, 1 enunciated in 
1903 in the following words, “ Sex in dioecious animals and plants 
is inherited in accordance with Mendel’s Law ; that is, in accordance 
with principles of dominance and segregation. The ordinary 
dioecious individual is a sex-hybrid or ‘ heterozygote ’ (Bateson), in 
which the characters of both sexes are present, one dominant, the 
other recessive. In the male, the female character is recessive, 
and conversely in the female, the male character; but each sex 
transmits the characters of both. 
The existence of each sex (in a latent condition) in the other is 
shown by the occurrence in each sex of rudimentary organs peculiar 
to the other.” 
Professor Castle then proceeds to give some cases which 
demonstrate the latency of the characters of one sex in the opposite 
one, and meets the possible objection that many of them may be 
1 Bull. Mus. Camp. Zoology, Harvard, Vol. XL., No. 9, 
