The studies of the relation of heat to the high infant mortality of summer have not yielded uniform results. A more careful review of the procedures which have been employed in these studies readily explains these contradictory conclusions. The external factors, such as food, high outdoor and indoor temperatures, circulation of air, etc., have received most of the attention; while the most important internal factor, i. e., the heat regulatory power of the infant, has been neglected by most authors. The question, then, which confronts us is: the reaction of the infant to the changes in its environment, with special reference to its heat regulation.
Heat equilibrium of the organism depends on the proper balance between:
I. Heat production,
II. Heat elimination.
I. Heat production is influenced chiefly by:
1. That food can influence heat production is shown by Rubner,1 who was able to increase