One of the vital equilibriums in man is the equilibrium involved in the maintenance of body temperature. Both chemical and physical factors are operative in sustaining this steady state, but the exigencies of the present war have emphasized anew the necessity of practical knowledge regarding the functional adjustments in acclimatization. Already battles have been fought in all the latitudes of the earth; utilizing air travel, Kiska and Murmansk are only hours away from New Guinea and North Africa. Furthermore, the ordinary altitude of aerial combat has risen to several times that which was common twenty-five years ago, and the concomitant decrease in temperature has raised serious problems.
One of the adjustments to increased environmental temperature is an increase in red cell and plasma volume,1 and the reversal of this change occurs when the subjects are exposed to cold. Apparently, this is a device for more effectively transferring body heat