Although creatin cannot be called a normal constituent of the urine in the same sense in which the invariably occurring creatinin, urea or uric acid are so designated, it is nevertheless found under circumstances that are strictly physiologic in character. Creatin is present only occasionally and in small quantity in the urine of adult men. It occurs in the urine of women post partum, and is usually present in the urine of children in which it may be equivalent in amount to a considerable portion of the closely related creatinin. In disease, particularly such types as are attended with partial starvation, creatin is also likely to make its appearance in the kidney output.
The explanation of the origin of this unquestionably important product of metabolism has remained a puzzle for many years. Nothing is known of the function of the creatin in the muscle and other organs; and it cannot