4 TEMPERATURE FLUCTUATIONS IN THE HUMAN BODY. 



difficulty in computing exactly the heat production, since this is dependent 

 upon an accurate measure of the body-temperature. In any method of meas- 

 urement thus far devised, the important assumption must be made that the 

 human body as a whole undergoes an average change in temperature corre- 

 sponding to the fluctuations found by measuring the temperature of any one 

 portion of the body. This last assumption has been based on such uncertain 

 evidence up to the present, that it has seemed desirable to investigate more 

 carefully the fluctuations in temperature of the different parts of the body. 



In taking up this problem, we were at once confronted with two rather 

 important questions: First, where is the best place to take the temperature of 

 the body; and second, are the fluctuations in temperature uniform throughout 

 the body? Certain reasoning might here be brought forward to prove that 

 the blood, being a great distributor of heat, equalizes the temperature through- 

 out the whole body, so that we should expect the temperature changes in the 

 different parts to follow a parallel course. If all parts of the body were of 

 essentially the same temperature, this might be easily assumed without ques- 

 tion; as a matter of fact, the temperature is not uniform, there being, as one 

 would naturally expect, a sharp thermal gradient. The accurate measurement 

 of the surface temperature presents many difficulties, but as a result of num- 

 erous observations made by different methods, 32 C. has been commonly 

 accepted as a standard, and is probably not far from the true value. The tem- 

 perature inside the body, on the other hand, is known to be not far from 37 C. ; 

 we have here, therefore, a gradient of 5 C. This gradient should be very 

 carefully studied before assuming that the temperature in different parts of 

 the body remains constant throughout the whole series of experiments. If the 

 source of heat is constant, as evidenced by the interior temperature of the 

 body, and the temperature of the environment does not change, there is every 

 reason for believing it probable that the gradient will be constant. 



Accordingly, in this particular research we have made a simultaneous study 

 of body-temperature, with reference to determining: (1) the best place for an 

 accurate and constant measurement of body-temperature; (2) the tempera- 

 ture gradient of the body; and especially (3) whether or not the temperature 

 fluctuations occurring in the different parts of the body are uniform. 



LOCALITIES FOR TEMPERATURE MEASUREMENT. 

 NATURAL CAVITIES. 



A physical examination of the body shows that there are a number of natural 

 cavities which provide favorable opportunity for measuring the body-tem- 

 perature, since thej r are surrounded by living tissue and not subjected to the 

 immediate effects of the external environmental temperatures. Of these 

 cavities, by common consent of practically all physiologists, the rectum is 

 considered to be the most favorable and to indicate the truest temperature of 

 the interior of the body. Its use, however, is practicable only in experiments 

 with patients who are bed-ridden and in physiological tests. With female 



