The use of inoculation malaria as a method of pyretotherapy still involves a relatively high figure of mortality and has other drawbacks. For example, there are the difficulties in propagating the culture, the loss of time entailed by the periods of incubation and removal of the fever, the uncertainty whether the inoculation will be successful, and the impossibility of a simultaneous administration of arsenical preparations; further, the fact that the treatment cannot be repeated satisfactorily, together with the occurrence of splenic and hepatic complications. A method of inducing pyrexia that promises freedom from these, at times, irksome conditions is therefore worthy of trial.