corpuscles of man and woman the relation of 5 to 4.7, and Hayem confirmed this by numeration. Cadet found in woman on the average 4.9 million corpuscles per cubic millimeter, and in man 5.2 million. More recently Korniloff, using still another method—the spectroscope of Vierordt—has reached about the same result. The proportion of red blood-corpuscles varies according to individual constitution, race, and sex. In robust men Lacanu found 136 red corpuscles in 1,000; in weak men, only 116 in 1,000; in robust women, only 126 in 1,000; and in weak women, 117.⁶¹ Professor Jones has taken the specific gravity of the blood of above 1,500 individuals of all ages and of both sexes.⁶² An examination of his charts shows that the specific gravity of the male is higher than that of the female between the ages of 16 and 68. Between the ages of 16 and 45 the average specific gravity of the male is about 1,058, and that of the female about 1,054.5. At 45 years the specific gravity of the male begins to fall rapidly and that of the female to rise rapidly, and at 55 they are almost equal; but the male remains slightly higher until 68 years, when it falls below that of the female. The period of marked difference in the specific gravity of the blood is thus seen to be coincident with the period of menstruation in the female. A chart constructed by Leichtenstern, based upon observations on 191 individuals and showing variations in the amount of hæmoglobin with age, is also reproduced by Professor Jones, suggesting that the variations in specific gravity of the blood with age and sex are closely related to variations in the amount of hæmoglobin. Leichtenstern states that the excess in men of hæmoglobin is 7 per cent. until the tenth year, 8 per cent. between 11 and 50 years, and 5 per cent. after the fiftieth year.⁶³ Jones states further⁶⁴ that the specific gravity is higher in persons of the upper classes and lower in the poorer classes. Observations of boys who were inmates of workhouses gave a mean specific gravity of 1,052.8 and on schoolboys a mean of 1,056, while among the undergraduate students of Cambridge University he found a mean of 1,059.5. Several men of very high specific gravity in the last group had distinguished themselves in athletics. "Workhouse boys are in most cases of poor physique, and one can hardly find a better antithesis than the general type of physique common among the athletic members of such a university as Cambridge."⁶⁵ There is no more conclusive evidence of an organic difference between man and woman than these tests of the blood. They permit us to associate a high specific gravity, red corpuscles, plentiful hæmoglobin, and a katabolic constitution.

A comparison of the waste products of the body and of the quantity of materials consumed in the metabolic process indicates a relatively larger consumption of energy by man. It is stated that man produces more urine than woman in the following proportion: men, 1,000 to 2,000 grams daily; women, 1,000 to 1,400 grams. As age advances, the amount diminishes absolutely and relatively in proportion to the diminution of the energy of the metabolic process. A table prepared from adults of both sexes, twenty-five years of age, of the average weight of sixty kilograms, shows a larger proportion both of inorganic and organic substances in the urine of men.⁶⁶ Milne Edwards has found that the bones of the male are slightly richer in inorganic substances than those of the female.⁶⁷

The lung capacity of women is less, and they consume less oxygen and produce less carbonic acid than men of equal weight, although the number of respirations is slightly higher than in man. On this account women suffer deprivation of air more easily than men. They are not so easily suffocated, and are reported to endure charcoal fumes better, and live in high altitudes where men cannot endure the deprivation of oxygen.⁶⁸ The number of deaths from chloroform is reckoned as from two to four times as great in males as in females, and this although chloroform is used in childbirth. Children also bear chloroform well.⁶⁹ Women, like children, require more sleep normally than men, but "Macfarlane states that they can better bear the loss of sleep, and most physicians will agree with him.... One of the greatest difficulties we have to contend with in nervous men is sleeplessness, a result, no doubt, of excessive katabolism."⁷⁰ Loss of sleep is a strain which, like gestation, women are able to meet because of their anabolic surplus. The fact that women undertake changes more reluctantly than men, but adjust themselves to changed fortunes more readily, is due to the same metabolic difference. Man has, in short, become somatically a more specialized animal than woman, and feels more keenly any disturbance of normal conditions, while he has not the same physiological surplus as woman with which to meet the disturbance.

Lower forms of life have the remarkable quality of restoring a lost organ, and of living as separate individuals if divided. This power gradually diminishes as we ascend the scale of life, and is lost by the higher forms. It is a remarkable fact, however, that the lower human races, the lower classes of society, women and children, show something of the same quality in their superior tolerance of surgical disease. The indifference of savage races to wounds and loss of blood has everywhere been remarked by ethnologists. Dr. Bartels has formulated the law of resistance to surgical and traumatic treatment in the following sentence: "The higher the race, the less the tolerance, and the lower the culture-condition in a given race, the greater the tolerance."⁷¹ The greater disvulnerability of women is generally recognized by surgeons. The following figures from Lawrie,