in condition to keep up the supply of fat which we not only require for constant use but probably need to change continually.  The steady or rapid lessening of the deposits of hydro-carbons stored away in the areolae of the tissues is of importance, as indicating their excessive use or a failure of supply; and when either condition is to be suspected it becomes our duty to learn the reasons for this striking symptom.  Loss of flesh has also a collateral value of great import, because it is almost an invariable rule that rapid thinning is accompanied soon or late with more or less anaemia, and it is uncommon to see a person steadily gaining fat after any pathological reduction of weight without a corresponding gain in amount and quality of blood.  We too rarely reflect that the blood thins with the decrease of the tissues and enriches as they increase.

Before entering into this question further, I shall ask attention to some points connected with the normal fat of the human body; and, taking for granted, here and elsewhere, that my readers are well enough aware of the physiological value and uses of the adipose tissues, I shall continue to look at the matter chiefly from a clinical point of view.

When in any individual the weight varies rapidly or slowly, it is nearly always due, for the most part, to a change in the amount of adipose tissue stored away in the meshes of the areolar tissue.  Almost any grave change for the worse in health is at once betrayed in most people by a diminution of fat, and this is readily seen in the altered forms of the face, which, because it is the always visible and in outline the most irregular part of the body, shows first and most plainly the loss or gain of tissue.  Fatty matter is therefore that constituent of the body which goes and comes most easily.  Why there is in nearly every one a normal limit to its accumulation we cannot say, nor yet why this limit should vary as life goes on.  Even in health the weight of men, and still more of women, is by no means constant, but, as a rule, when we are holding our own with that share of stored-up fat which belongs to the individual we are usually in a condition of nutritive prosperity, and when after any strain or trial which has lessened weight we are slowly repairing mischief and laying by fat we are equally in a state of health.  The loss of fat which is not due to change of diet or to exercise, especially its rapid or steady loss, nearly always goes along with conditions which impoverish the blood, and, on the other hand, the gain of fat up to a certain point seems to go hand in hand with a rise in all other essentials of health, and notably with an improvement in the color and amount of the red corpuscles.

The quantity of fat which is healthy for the individual varies with the sex, the climate, the habits, the season, the time of life, the race, and the breed.  Quetelet[3] has shown that before puberty the weight of the male is for equal ages above that of the female, but that towards puberty the proportional weight of the female, due chiefly to gain in fat, increases, so that at twelve the two sexes are alike in this respect.  During the child-bearing time there is an absolute lessening on the part of the female, but after this time the weight of the woman increases, and the maximum is attained at about the age of fifty.