44 TEMPERATURE FLUCTUATIONS IN THE HUMAN BODY. 



a temperature 2 or 3 C. higher than that of the body, was placed in the 

 inclosed portion for 5 minutes before inserting the thermometer. By this 

 means the cavity was preheated to approximately normal temperature, and 

 came to its final value in about half of the time previously required. 



SIMULTANEOUS OBSERVATIONS OF BODY-TEMPERATURE IN 



DIFFERENT LOCALITIES. 



From the previous discussion of the thermal gradient it is obvious that it 

 would be practically impossible to determine the average temperature of the 

 human bod}-, although as a gradient effect is most marked in the last peripheral 

 4 centimeters of body material, a large portion of the body would have a tem- 

 perature not far from that of the rectum. Fortunately, for purposes of calorim- 

 etry, what is chiefly desired is the fluctuations in temperature from hour to 

 hour or from day to day. One must be sure that the fluctuations in tempera- 

 ture throughout the whole body are of equal value, since otherwise no accurate 

 estimate can be made of the total heat gained or lost due to a rise or fall in 

 temperature. 



The temperature of the body rarely remains constant, even for so short a 

 time as 10 minutes; this was shown by a series of observations 1 made every 4 

 minutes for several days in which practically no two consecutive readings were 

 exactly alike. The normal temperature rhythm, with a maximum between 4 

 and 5 o'clock in the afternoon and a minimum between 2 and 5 o'clock in the 

 morning, is considerably accentuated by a number of extraneous factors, but 

 even with the subject lying in bed without food, or with a small amount of food, 

 the range in temperature in 24 hours may be as high with a normal subject 

 as 1.3 C. (2.3 F.). 



In the collected results of body-temperature measurements obtained in a 

 large number of experiments with the respiration calorimeter at Wesleyan 

 University, Benedict and Carpenter 2 report that the average body-temperature 

 in experiments with food was 36.82 C. (98.3 F.),the minimum being 35.67 C, 

 and the maximum, 38.23 C. The average range for all of the experiments 

 was 0.96 C, the minimum range, 0.44 C, and the maximum, 1.64 C. In a 

 series of experiments with 11 subjects in which food was not taken, covering in 

 all 31 days of 24 hours each, the average temperature of the subjects was 

 36.67 C. (98 F.). The minimum temperature observed was 35.53 C, and 

 the maximum, 37.74 C. The average range in temperature was 0.77 C, the 

 minimum range being 0.38 C, and the maximum, 1.36 C. (2.45 F.). 



The large number of observations made on body-temperature by electrical 

 methods in the last few years have shown that there are fluctuations aside 

 from the normal rhythm fluctuations that can be produced artificially; for 

 example, changing from a lying to a sitting position will cause a slight rise in 

 temperature, as will also the taking of hot drinks or hot food. Eating a meal 

 ma}' cause a rise of as much as 0.15 C. in 20 minutes, and severe muscular 



Benedict and Snell, Archiv f. d. ges. Physiol., 1902, 90, p. 33. 



'Benedict and Carpenter, Publication No. 126, Carnegie Institution of Washington, 

 1910, p. 121. 



