The composition of the blood in man and woman is as follows: Water, man, 77.19; woman, 79.11. Solid matter, man, 22.10; woman, 20.89. Blood corpuscles, man, 14.10; woman, 12.79. Number of blood corpuscles in a cubic millimeter of blood, man, 4 1/2 to 5 millions; woman, 4 to 4 1/2 millions. According to Meynert, the weight of the brain of man is from 1,018 to 1,925 grams; of woman, from 820 to 1,565; or in the relation of 100 to 90.93. LeBon and Bischoff agree that, while weight of brain corresponds with size of body, nevertheless short people have relatively larger brains. With woman, the smaller size of the heart, the narrower system of blood vessels and probably also the larger quantity of blood, has a lower degree of nourishment for its effect.[133] That, however, the larger skulls of larger persons, coupled with the quantitative changes occasioned by the size of the skull promote the vigor of the several sections of the brain is a matter that _cannot be asserted_.[134] Of 107 mentally healthy men and 148 women of the ages of 20 to 59, the weight of the brain per thousand was: Average Medulla Length in Sex. Oblongata. Cerebellum. Pons. 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.