All facts are best studied in the light of an idea. It may be conducive to clearness, therefore, to mention first the leading theories now in the field concerning woman's peculiarities. It has often been asserted since Aristotle that woman is a stunted or inferior man and represents arrested development. Again, it has been said that woman is a grown-up child, that she belongs to the child type, and must ever to some extent retain the child relation. Again, more recently, it has been maintained that although woman belongs to the child type, yet the child type is in truth the race type and represents greater perfection than is represented by man, whose natural characteristic is senility. Finally, it has been said that throughout the whole animal world, where artificial circumstances have not modified natural relations, the female stands for physical superiority in size and vitality, and more truly represents the essential qualities of the species. Without prejudice for or against any of these theories, let us see what evidence there may be for each.
Psychology is no longer studied apart from physiology. We must therefore first notice some of the secondary sexual characteristics of woman in respect to her physical structure. Although we are chiefly concerned with the nervous system, a few other points may first be mentioned. Woman among all civilized races is both shorter and lighter than man, except at the age of thirteen or fourteen in our climate, when girls are both taller and heavier than boys of like age. Woman's form is more rounded and graceful, less bony and angular, having relatively more fat and less muscle. Her muscular tissue contains a slightly larger percentage of water. As shown by the dynamometer, woman's strength is at the most only about two thirds that of man, while her height is as sixteen to seventeen and her weight as nine to ten. In woman the trunk is, relatively to the length of the arms and legs, longer than in man. Owing to the greater inclination of the pelvis, woman is somewhat less erect than man. The head also is carried less upright, and the gait is comparatively unsteady and indirect. The greater length of the first finger as compared with the third is a feminine peculiarity. This relation, seldom found in man, is not uncommon among women. It gives grace to the hand, and would seem to be an instance of higher evolution, not being found among apes or savages. The vocal cords in woman are shorter and the voice is higher and shriller. The larynx is smaller and higher in the throat. The thyroid gland is considerably larger than in man. It is thought that women in respect to hair and eyes are slightly darker than men, but this has not been verified. Woman's lung capacity is in proportion to her size much less than man's, and the amount of carbonic acid expired is relatively less. Differences in the blood are well
