648 PYREXIA. [Book ii. 



maximum ranging from 9 a.m. to 6 P.M. and the minimum 

 from 11 p.m. to 3 A.M. Meals cause sometimes a slight eleva- 

 tion, sometimes a slight depression, the direction of the influ- 

 ence depending on the nature of the food : alcohol seems 

 always to produce a fall. Exercise and variations of external 

 temperature, within ordinary limits, cause very slight change, 

 on account of the compensating influences which have been 

 discussed above. The rise from even active exercise does not 

 amount to 1° ; when labour is carried to exhaustion a depres- 

 sion of temperature may be observed. In travelling from very 

 cold to very hot regions a variation of less than a degree occurs, 

 and the temperature of inhabitants of the tropics is practically 

 the same as of those dwelling in arctic regions. 



§ 431. Many of the maladies of the body are characterized 

 by an increase 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 cannot long be borne with- 

 out 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 inflamma- 

 tion 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 dis- 

 cuss the connection between the local inflammation or the spe- 

 cific poison and the high temperature, but we have increasing 

 evidence that the high temperature 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 consumption 

 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 metabolism of the skeletal muscles as, 

 unlike an ordinary contraction, directly involves the nitroge- 

 nous elements. The inordinate metabolism of the body at 

 large thus characteristic of fever is shewn by the wasting 

 which it entails. Calorimetric observations also shew 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 regulation 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 



