Heat Elimination and Production. 101 



ination is by no means synonymous with heat production, and obviously in 

 comparisons with the energy transformations computed from the gaseous ex- 

 change, we must use the total heat production rather than the heat elimination. 

 In some of the earlier experiments, the necessity for this distinction was not 

 so clearly brought out, and the temperature measurements are not as satis- 

 factory as one could wish, particularly those temperature measurements taken 

 with the clinical thermometer in the mouth or the axilla. With the introduc- 

 tion of the electrical-resistance thermometers, however, much more accurate 

 body-temperature measurements can be made and continuously recorded. 



It is important here, however, to point out that there is at present a possi- 

 bility of error which may be very large, in the assumption necessitated by our 

 present deficient knowledge with regard to the temperature changes of the body 

 as a whole. At present we assume that any fluctuation of body-temperature 

 observed when measuring the temperature deep in the rectum indicates a cor- 

 responding fluctuation in the average body-temperature of the whole body. 

 This may or may not be true, and, as has been pointed out previously, it is 

 highly desirable that a topographic study of body-temperature be made in order 

 to indicate whether or not a change in temperature of 1 deep in the rectum 

 is accompanied by a change in temperature of 1 in the axilla or mouth, or 

 on the surface of the body. 



EXPERIMENTS ON HEAT ELIMINATION AND HEAT PRODUCTION. 



HEAT PRODUCTION DURING SLEEP. 



In discussing the heat production of man, the same general plan followed in 

 considering the carbon dioxide produced and oxygen absorbed will be adhered to 

 here, namely, to first consider the heat production of individuals during sleep 

 when the muscular activity is more nearly comparable in all cases. The heat 

 production, or if no accurate records of body-temperature were available, the 

 heat elimination was determined from 1 a. m. to 7 a. m. with 19 different sub- 

 jects, varying in body-weight from 55 kilos to 84.7 kilos. With a few subjects 

 but one experiment was obtained, but in most cases several periods were possible. 



The results of experiments with 19 different subjects have been computed 

 in so far as possible on the basis of heat production and placed in table 75. 

 The values were all obtained during the period of 1 a. m. to 7 a. in., repre- 

 senting the subject in minimum muscular activity and during the greater part 

 of the time in profound sleep. The body-weight and height for each subject 

 are also given in the table. The heat production per hour varies from 56 

 calories in the case of the subject A. H. M. to 82.7 calories with the subject 

 J. C. W. The average heat production for all the subjects was 70.9 calories. 

 In order to compare the experiments more satisfactorily, they were computed 

 on the basis of the heat production per kilogram of body-weight per hour, and 

 the results vary from 0.86 calorie with the subject W. 0. A. to 1.37 calories 

 with the subject H. E. S. The average heat production per kilogram of body- 



