AND PERSONALITY 



large heart, and the large blood volume of civilized man is 

 so great that heatstroke becomes imminent. 



Consider how rapidly the temperature of man rises in a 

 bath which is higher than body temperature. Civilized man is 

 so highly energized that unless he can lose heat at a high rate 

 his temperature will rise to the critical level of heatstroke. 



The studies of the basal metabolic rate of Eskimos, made 

 by Dr. Quiring, Dr. Thomas Mailing,, and me, showed the 

 Eskimos to have a basal rate about .22 per cent higher than 

 civilized man in Cleveland, Ohio. In the tropics Francis 

 Benedict found the metabolism lower than that found in 

 man of the temperate zone. These values express the size 

 of the brain, the thyroid gland, the heart and blood volume 

 as an adaptation to external temperature. Thus the cycles of 

 humidity in the north temperate zone interfere vitally with 

 the needed loss of heat to the surrounding air, hence to 

 the tendency to heat prostration and death from heatstroke. 



In addition to the variables in temperature and the 

 variables in humidity, a third factor has an important 

 bearing on the energy factors of man. This factor is the 

 variability of the barometric pressure. 



The influence of oxygen tension on metabolism is so 

 important that in metabolic observations it is necessary, 

 among other conditions, to have barometric readings, and 

 the influence of barometric changes is expressed in the me- 

 tabolism. Thus we can now understand why a rapidly falling 

 barometer brings universal depression to a population. 



In the preceding pages we reported our studies of the 

 varying influence of oxygen tension upon the brain and the 

 thyroid gland in fish. In our studies we collected many fish 

 and reptiles in habitats of variable oxygen tension, such as 

 the still tropical waters, the shallow shoals of sandy beaches, 

 bubbling with air and oxygen, and the cold arctic sea with 

 its rich supply of oxygen. What did we find ? 



We found that the gameness of the fish that is, its 



241 



