The sharp distinction into two kinds of individuals, males and females, characteristic of so many animals, is occasionally done away with when an individual appears that bears the structures peculiar to the male in some parts and to the female in other parts of the body. Such an individual may show not only the secondary sexual differences(either sex-limited or sex-linked) of male and female, but gonads and genitalia of both kinds as well. We speak of these as gynandromorphs...But the chief importance of these rare combinations lies in the opportunity they furnish for analysis of the changes in the hereditary mechanism of sex determination that makes such combinations possible.

THE ORIGIN OF GYNANDROMORPHS.
BY T. H. MORGAN AND C. B. BRIDGES, 1910.