The effect of moderately high atmospheric temperatures upon the formation of hemolysins

The experiments which have been reported in regard to the effect of high atmospheric temperatures upon susceptibility to bacterial infections, or upon the immunity reactions in response thereto, seem at first sight to be conflicting and unsatisfactory. Some authors report increased resistance as a result of external heat and others precisely the reverse. A more careful analysis shows however that if the several factors at work in such experiments and the various conditions employed by different investigators be considered, the results are reasonably harmonious. A moderate amount of heat may naturally be expected to produce a different result from temperatures so severe as to lead to a condition of fever in the experimental animals; and exposure to a hot atmosphere may produce one effect on the susceptibility of an animal to subsequent infection and quite another on the course of an infection already established.

The majority of investigators have been chiefly interested in the effect of the condition of fever upon recovery from infection, and have therefore exposed their animals to atmospheric conditions sufficiently extreme materially to increase the body temperature. Experiments of this kind have quite uniformly indicated that the progress of an infection already established is in greater or less degree checked by an artificial fever due to a very high atmospheric temperature, or produced by the Sachs-Aronson operation. Such experiments have been made and such a conclusion reached by Rovighi, Walther, Filehne, Hildebrandt, Loewy and Richter, Kast, Engelhardt, and Rolly and Meltzer. In all these experiments the high atmospheric temperatures used were 35“-4I” C. and the body temperatures of the animals 40°-42°. Vincent and Sacqubpbe and Loiseleur on the other hand found resistance lowered by high heating, but for the most part their experiments were concerned with the lighting up of latent infection or the invasion of bacteria from the digestive tract, a very different phenomenon from the progress of the struggle for immunity against an infection already established.