The general concept of the effect of fever has been markedly altered since Welch1 in 1888 first lectured on the beneficial effects of increased body temperature. It is now well recognized that the defense mechanism of the body is stimulated by increased temperature, and in many diseases an attempt has been made to aid physiologic processes by producing artificial fever. Although many methods have been advocated for temporarily increasing the thermal level of the body, nevertheless the greatest impetus to the study of hyperpyrexia came with the discovery that high frequency currents were capable of producing heat in living structures. This finding was originally made by d'Arsonval in 1893, but the clinical significance was not recognized until the more recent studies of Hosmer2 and the clinical reports of Neymann and Osborne3 and later of Carpenter.4
As Coulter and Osborne5 have pointed out, this heating of