By means of a stethoscope and electric signalling system the pulse rate of 100 albino rats, weighing 92-210 gm., was determined. The rate was 270-350 beats (average 305). The average of the lowest counts recorded for each rat was 281 beats per min. In 20 animals comfortably held by an assistant the basal rate was elevated from 305 to 538 beats. When the same rats were forcibly fettered on an animal board the rate was further increased to 656.