Much investigation has been done on the physiology of the muscles of the vertebrates as compared with that of the invertebrates. Buddington (\u2702) brings together the bibliography bearing on this problem, and shows that with increasing temperature Lumbricus muscle shows little constancy in changes of tone below 15° C and the first uniform result is a gradual loss of tone beginning at 20° C; rapid loss of tone occurring between 30° and 40°; an improvement from 42° to about 55° when rapid relaxation sets in, this changing to final heat rigor at about 65°
