“…- Hart (3) states that guinea-pigs show paralysis of the hind legs when human thymus is injected intraperitoneally, while no effect was observable as a result of the intraperitoneal injection of calf thymus. Mifller (4) observed a beneficial effect on the fatigued muscle of the frog as the result * The work for this and the following paper was completed in April, 1920. of the injection of thymus extract into the blood-stream. The same result was obtained by Del Camp 0 (5) in the rabbit.…”