2. The branches of blood vessels, supplying the subcortical centers from the base, are short, thick, straight, palisade-like, while those on the surface of the brain, supplying the cortex, run in long tortuous lines. And it is because of that, since with the increased length of the blood vessels the resistance to the propulsive force of the heart is increased, that the subcortical centers, the moment fatigue supervenes, are better supplied with blood than the cortex, they are less readily fatigued than the more readily exhaustible cerebrum. 3. Because of this and because of the more watery character of woman's blood and great extent of subcortical centers in woman in comparison with cerebrum, the physical equilibrium of woman is more unstable than of man. 4. All nerves (except the optic and olfactory, which spread out directly in the cortex, save some of their filaments terminating in the subcortical centers) terminate in the subcortical center; the cortex of the cerebrum acts as a checking organ for the subcortical center; as the cerebral cortex in woman, as already stated, is at a disadvantage not only from the anatomical standpoint, but also in the quality of its blood supply, woman is not only more easily fatigued, but also more readily excitable (irritable, nervous). These facts explain, on the one hand, what is called the superior endowment of woman, and, on the other, her inclination to sudden changes of opinion, as well as to hallucinations and illusions. This state of unstable equilibrium between the _dura mater_ and the _pons_ becomes particularly normal during menstruation, pregnancy, lying-in, and at her climacteric. As a result of her physical organization, woman is more inclined to melancholy than man, and likewise is the inclination to mental derangement stronger with her; on the other hand, the male sex excels her in the number of cases of megalomania. Such, in substance, is the information furnished us by the authority whom we have been quoting. As a matter of course, in so far as the cited differences depend upon the nature of the sex-distinctions, they can not be changed; in how far these differences in the make-up of the blood and the brain may be modified by a change of life (nourishment, mental and physical gymnastics, occupation, etc.) is a matter that, for the present, lies beyond all accurate calculation. But this seems certain: _modern woman differs more markedly from man than primitive woman, or than the women of backward peoples, and the circumstance is easily explained by the social development that the last 1,000 or 1,500 years forced upon woman among the nations of civilization_. According to Lombroso and Ferrero, the mean capacity of the female skull, the male skull being assumed at 1,000, is as follows:--