The gentlemen who have done me the honor to follow my clinical service at the State Infirmary for Diseases of the Nervous System[2] are well aware how much care is there given to learn whether or not the patient is losing or has lost flesh, is by habit thin or fat. This question is one of the utmost moment in every point of view, and deserves a larger share of attention than it receives. In this hospital it is the custom to weigh our cases when they enter and at intervals. The mere loss of fat is probably of small moment in itself when the amount of restorative food is sufficient for every-day expenditure, and when the organs are 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 areolæ 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 anæmia, 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.