The doctrine of the existence of different degrees of masculinity and femininity may be treated, in the first place, on purely anatomical lines. Not only the anatomical form, but the anatomical position of male and female characters must be discussed. The examples already given of sexual differences in other parts of the body showed that sexuality is not limited to the genital organs and glands. But where are the limits to be placed? Do they not reach beyond the primary and secondary sexual characters? In other words, where does sex display itself, and where is it without influence? Many points came to light in the last decade, which bring fresh support to a theory first put forward in 1840, but which at the time found little support since it appeared to be in direct opposition to facts held as established alike by the author of the theory and by his opponents. The theory in question, first suggested by the zoologist J. J. S. Steenstrup, of Copenhagen, but since supported by many others, is that sexual characters are present in every part of the body. Ellis has collected the results of investigations on almost every tissue of the body, which serve to show the universal presence of sexual differences. It is plain that there is a striking difference in the coloration of the typical male and female. This fact establishes the existence of sexual differences in the skin (cutis) and in the blood-vessels, and also in the bulk of the colouring-matter in the blood and in the number of red corpuscles to the cubic centimetre of the blood fluid. Bischoff and Rudinger have proved the existence of sexual differences in brain weight, and more recently Justus and Alice Gaule have obtained a similar result with regard to such vegetative organs as the liver, lungs and spleen. In fact, all parts of a woman, although in different degrees in different zones, have a sexual stimulus for the male organism, and similarly all parts of the male have their effect on the female.