504 NUTRITION. 



exercise does not amount to 1 ; when labor is carried to exhaustion a de- 

 pression of temperature may be observed. In travelling from very cold to 

 very hot regions a variation of less than a degree occurs, and the tempera- 

 ture of inhabitants of the tropics is practically the same as of those dwell- 

 ing in arctic regions. 



451. Many of the maladies of the body are characterized by an in- 

 crease of the bodily temperature known as " fever " or " pyrexia," the 

 thermometer very frequently rising to 39 or 40, not unfrequently to 41, 

 and at times reaching 43 or even 44 ; but these higher temperatures can- 

 not long be borne without the organism failing. And, as we have said, any 

 increase in man of the bodily temperature beyond 38, or even beyond 37.5, 

 indicates some disturbance. In most cases the rise of temperature has a 

 definite objective cause, some local inflammation or suppuration, or, as in 

 specific fevers, the presence in the economy of some " materies morbi," of 

 the nature of an organized germ or of some other nature. We cannot here 

 discuss the connection between local inflammation or the specific poison and 

 the high temperature, but we have increasing evidence that the high tem- 

 perature of fever is due, not merely to a diminution of the loss of heat, 

 though this may be a factor, but also, and indeed chiefly, to an increased 

 production of heat. In fever the production of carbonic acid and the con- 

 sumption of oxygen, that is to say, the metabolic changes of the tissues, are 

 increased. The urea also is increased, and that in such a way as to confirm 

 the view already expressed that much of the heat comes from such a metab- 

 olism of the skeletal muscles as, unlike an ordinary contraction, directly 

 involves the nitrogenous elements. The inordinate metabolism of the body 

 at large thus characteristic of fever is shown by the wasting which it entails. 

 Calorimetric observations also show in a direct manner that the production 

 of heat is increased. Of course, mere increased production alone would be 

 insufficient to raise the temperature of the body, for it might be met, up to 

 a very high limit, by a compensating increase of loss of heat ; but in fever 

 this compensation is wanting, and it is perhaps this absence of due regu- 

 lation which is most characteristic of the febrile condition. 



In some maladies the bodily temperature falls distinctly below the normal 

 average, reaching for instance 35, or even lower. In such cases there can 

 be little doubt that the condition is due to diminished metabolism and 

 diminished heat production. 



One of the most marked phenomena of starvation is the fall of tempera- 

 ture, which becomes very rapid during the last days of life The lowered 

 metabolism diminishes the production of heat, and the lowered temperature 

 in turn still further diminishes the metabolism. Indeed, the low tempera- 

 ture is a powerful factor in bringing about death, for life may be much 

 prolonged by wrapping a starving animal in some bad conductor, so as to 

 economize the bodily heat. 



452. Effects of great heat. As we said above, the regulative heat 

 mechanism is unable to withstand the strain of too great an external heat or 

 too prolonged an exposure to a great but less degree of heat. The tempera- 

 ture of the body then rises above the normal ; and it has been observed that 

 the temperature is more easily raised by warmth than depressed by cold, at 

 least when neither is very intense. When either in this way by external 

 warmth or through pyrexia the temperature of the body is raised some 6 

 or 7 above the normal, to 45 or thereabouts, death speedily ensues. The 

 chain of events thus leading to death has not been as yet clearly made out, 

 and most likely the events do not take exactly the same course in all cases ; 

 but we shall probably not go far wrong in attributing death to the fact that 

 the high temperature hurries on the metabolism of the several tissues, of 



