The return of patients to normal after pneumonia, typhoid and typhus fevers and the other infectious diseases is a phenomenon with which we all are familiar clinically, yet convalescence up to the present has not been investigated in any exact or quantitative way. The length of time during which convalescent patients are confined to bed and the resumption of normal life are graduated very differently by different practitioners. In view of this great variation in procedure any accurate or quantitative method by which we could observe the stage of a patient's convalescence would be very desirable.
At present the need for such an accurate method of following a patient's convalescence is rendered acute by the military situation. We have in training a great number of young men, many of whom are being attacked by infectious diseases. In the treatment of these patients efficiency demands that their absence from military duties