With an electric method employing radio amplification for transmittal of the action currents of the heart to a sensitive Moll galvanometer and special electrodes, records were obtained of the heart rates of 37 adult, female, Indian elephants, the largest weighing 8,000 and 9,000 pounds.
When the elephants were standing quietly under ordinary conditions of feeding, the rates averaged 30 beats per minute. The lowest rate was 22 and the highest, 39 beats. This latter was found with the only elephant that presented any disciplinary problem and is explained by her extreme nervousness.
When the elephants were lying, the rates were higher, occasionally only one or two beats higher, but usually from 8 to 10 beats higher.
This is contrary to the findings with all other animals, which have lower heart rates when lying. In general, the smallest animals have the highest heart rates. The canary has been reported to have a rate of 1,000 beats, and the large domestic animals show rates of 40 or 50 beats. The elephant, with a rate of about 30 beats, fits perfectly into the picture, being the largest animal and having the lowest heart rate of any of the animals thus far studied.