352 du bois: basal energy requirement of man 



method is purely chemical. The carbon dioxid production of 

 each hour is measured, also the oxygen consumption. Knowing 

 these and the nitrogen elimination in the urine, we can calcu- 

 late out the grams of carbohydrate, fat, and protein metabolized 

 each hour, and from their well known caloric values can de- 

 termine the total heat production. In normal controls the two 

 methods agree very closely, if we take the averages of all the 

 experiments made. Even in periods as short as one hour the 

 agreement is usually within 5 per cent. 



This calorimeter in Bellevue is particularly well adapted to 

 observations on patients. It is situated in a room next to a 

 small metabolism ward where the food can be weighed out ac- 

 curately and complete twenty-four hour specimens of urine 

 collected. The experimental period within the chamber is only 

 three hours, as contrasted with the long periods of one to ten 

 days needed in the old Atwater-Rosa chamber in Middletown. 

 The patient lies on a comfortable bed, breathing pure air at a 

 uniform temperature. Even patients who are seriously ill can 

 serve as subjects of the observation without the slightest harm 

 being done. As a matter of fact they are greatly benefited, be- 

 cause their diets can be arranged scientifically as a result of the 

 information obtained in the calorimeter. 



In order to understand the results obtained in disease we 

 must first consider the basal metabolism of normal men. With 

 most individuals this is surprisingly uniform from day to day 

 and from year to year. Of course the heat production of a 

 man depends largely on his size, but it is by no means propor- 

 tional to the body weight. A large man gives off more heat than 

 a small man but for each kilogram of weight the small person 

 has the higher metabolism. On the other hand the metabolism 

 of men of various sizes and shapes is rather closely proportional 

 to the surface area of the body. Many years ago Rubner estab- 

 lished this law of surface area and was able to show that mice, 

 rabbits, dogs, men, and horses had almost the same metabolism 

 per square meter of skin. 



Up to the last few years we were obliged to estimate the sur- 

 face area of men by Meeh's formula which was simple but, unfor- 



