en. xxxix.] 



METABOLISM IN DISEASE 



593 



occurs on a hot as compared with a cold day, does not produce fever,* 

 because the production of heat within the body is correspondingly 

 diminished. In fever there is increased production of heat, as is 

 seen by the study of exchange of material ; the intake of food is, as 

 a rule, very small ; the discharge of nitrogen and carbon results from 

 the disintegration of tissues, which, as compared with that in simple 

 inanition, is large ; the tissues are said to be in a labile condition, 

 that is, they are easily broken down. In most febrile states, the 

 skin is dry, the sweat-glands, like most of the secreting organs of 

 the body, being comparatively inactive, and so the discharge of heat 

 is lessened. The skin may, however, sometimes be bathed in perspira- 

 tion, and yet high fever be present. The essential cause of the high 

 temperature is neither increased formation nor diminished discharge 

 of heat, but an interference with the reflex mechanism, which in 

 health operates so as to equalise the two. 



Increased nitrogenous metabolism in fever has been observed 

 in pneumonia, in pyaemia, and in other febrile conditions. Einger 

 showed the correspondence in temperature and output of nitrogen 

 very clearly in intermittent fever (ague). 



What is known as the epicritical increase of urea is the greatly 

 increased secretion of urea that occurs at the commencement of the 

 defervescence of a fever. It is probably not due to an increased 

 formation of urea, but to the removal of urea which has accumulated, 

 owing to the fact that the kidneys have been acting sluggishly during 

 the height of the fever. 



Increased output of carbonic acid also occurs in fever. 



Other changes noted in fever are a rapid loss of the liver glycogen, 

 a lessening of chlorides in the urine, and often an increase of the 

 urobilin in the urine. 



The following table illustrates exchange of material in fever, no 

 food being taken : 



A febrile condition does occur on undue exposure to a tropical sun, for 

 instance in soldiers in India ; this is mainly due to their tight-fitting and otherwise 

 unsuitable clothing, which interferes with the proper action of the skin. 



2 P 



