Sex. | Medulla Oblongata. | Cerebellum. | Pons. | Average Length in Centimeters. |
| Men | 790 | 107.5 | 102 | 166.5 |
| Women | 787 | 110.0 | 103 | 156.0 |
The absolute and relative excess in the weight of the cerebellum of woman has an enormous significance. With animals that run immediately upon birth, the cerebellum is much more powerfully developed than with animals that are born blind, are helpless, and that learn to walk with difficulty. Accordingly, and in consequence of its connection with the cerebrum, subcortical center and the spinal cord, the cerebellum is a station of the muscular and of the chief nervous system, by means of both of which qualities we keep our equilibrium. The more massive cerebellum with woman, together with the comparative shortness and tenderness of her bones, explains her comparative quickness and easiness of motion, her quicker and higher co-ordination of the muscles for their functions, and her knack of quickly sizing up a situation, and finding her way in the midst of a confusion of associations. Woman is furthermore aided in the latter faculty through the greater excitability of her cerebral cortex. Meynert says:—
1. All structural anomalies associated with anaemia of the blood—including also a small heart and narrow arteries—should be considered as subject structural defects. Upon this depends not only the ready exhaustibility of the cortex, but also the phenomena of irritability, named by Meynert, localized irritable weakness.
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.