TEMPERATURE TOPOGRAPHY 



713 



The daily curve of temperature shows a minimum in the early 

 morning, between two and six o'clock (36-3 C.), and a maximum 

 in the evening, between five and eight o'clock (37*5 C.) ,(Fig. 227), 

 The daily range in health may be taken as a little over i C., 01 

 about 2 F. In fever it is generally greater, but the maximum and 

 minimum fall at the same periods; and it is of scientific, and also 

 of practical, interest that the early morning, when the temperature 

 and pulse-rate are at their minimum, is often the time at which the 

 flagging powers of the sick give way. From two to six o'clock in 

 the morning the daily tide 

 of life may be said to reach 

 low-water mark. Even in 

 a fasting man the diurnal 

 temperature curve runs its 

 course, but the variations 

 are not so great. The ta- 

 king of food of itself causes 

 an increase of temperature, 

 although in a healthy man 

 this rarely amounts to more 

 than half a degree. The rise 

 of temperature is certainly 

 due in part to the increased 

 work of the alimentary 

 canal, but it is in the main 

 connected with the increase 

 of metabolic activity which the entrance of the products of digestion 

 into the blood brings about. The heat-production is especially 

 increased by proteins. 



A dog weighing 15-3 kilos, the heat-production of which was 22-3 calo- 

 ries during an hour previous to feeding, was given 1,200 grammes of 

 meat at noon. The heat-production rose to 36 calories in the 2nd hour, 

 and 42 calories in the 3rd. It remained above 40 calories per hour 

 beyond the loth hour, and in the i4th hour it had only fallen to 37 calo- 

 ries, to reach 25 calories in the 2ist hour. On the whole, the increase 

 in heat-production ran parallel with, and was proportional to, the 

 increase in the excretion of nitrogen (Williams, Richie and Lusk). 

 The relatively unimportant share taken by the increased work of the 

 gastro-intestinal tract in the augmentation of the metabolism is illus- 

 trated by the fact that a high rate of heat-production was maintained till 

 the 1 4th hour, even although by this time three-quarters of the nitrogen 

 corresponding to the food protein had been eliminated in the urine, and 

 the work of digestion and absorption must have been largely completed. 



The rise of temperature during digestion is gradual, the maximum 

 being reached during the fourth hour, or even later. 



The cause of the daily variation of temperature has been much 

 discussed. There is no doubt that several factors are concerned, 

 among the most important being the variation in the amount of 

 contraction of the skeletal muscles and the influence of food. Mus- 



Fig. zij. Curve showing the Daily Variation 

 of Body-Temperature. 



