LOCAL AND SYSTEMIC EFFECTS OF HEAT AND COLD IN RATS

TEMPERATURE is one of the most powerful governors of life processes, since it affects nervous and circulatory functions, membrane permeability, gaseous dissociation and other external determinants of the oxygenation and nutrition of cells and also the action and coordination of enzymes and all other physical and chemical processes within cells. Numerous researches have only slightly illuminated this vast subject; also it is improbable that many laws can be found which are universally applicable to lower and higher, poikilothermic and homoiothermic, thermophilic and cold resistant organisms. In experiments on mammals, especially from a practical viewpoint, there is often insufficient regard for the considerable differences in thermal reactions between man and all the common laboratory species, and few investigators show any awareness of the contrasts between the reactions of the whole body, of parts normally connected with the body and of parts isolated from the body.¹ One law is actually universal,