The embryonic groundwork of the sexes is homologous, and the line of distinction, even in adult life, and under normal conditions, so subtle and indefinite as to invest it with a peculiar degree of interest. The physical structures of both male and female afford indubitable evidence of their common origin. Men have rudimentary breasts, capable, under the stimulus of suckling, of almost feminine development; and many cases are indeed recorded where fathers, through the death of the mother, have thus nursed the offspring through the regular period of lactation.
The raphe of the scrotum shows very distinctly where it was closed up to form the male, instead of remaining open as in the female; and women retain in the clitoris the rudimentary -penis of the man. Little difference exists in the sounds of the male and female voices up to the period of puberty, when the subtle process of differentiation culminates in the sometimes abrupt establishment of those anatomical and physiological characteristics which continue through life. Then the boy's voice changes, hair begins to grow on those parts of the body where it is commonly absent in the female, and the girl begins to take on, along with certain finer shades of sexual feeling, that shyness, softness and modesty which distinguish the sex. And it is at this point, I think, we may begin most profitably the study of sex, leaving the phenomena of its origin, source, and the various steps of its division and development to the more cognate science of embryology.1
•This view of sex is ably set furth in Ulrichs's treatise on the subject. "Sex," he asserts, "is only an affair of development. Up to a certain stage of embryonic existence all living animals are hermaphroditic. A certain number of them advance to the condition of what I cat) man, others to what I call woman, a third class becoming what I call umings. It ensues, therefore, that between these three sexes there are no primary, but only secondary, differences. And yet true differences, constituting sexual species, exist as facts." (Ulrichs, loc. cil., Section xrv.)