492 BIOLOGICAL PHYSICS 



condition must necessarily be dependent on, and deter- 

 mined by, the character and cause of the increase or 

 diminution, and of the particular part of the calorific 

 machinery involved in the particular instance. 



Thus a state of fever may be due to an increase in 

 the quantity of caloric contributed from one or more 

 of these sources, while a state of collapse may, in like 

 manner, be due to a lessened contribution, the various 

 degrees of increased and diminished temperature included 

 between these extremes being similarly determined. 



As a matter of everyday clinical experience, however, 

 we find it difficult to apportion, with any degree of exacti- 

 tude, the sources of increased or diminished temperature, 

 and so have to be content with an approximate attempt 

 at a solution of the complicated problem, and a corre- 

 spondingly empirical choice and administration of our 

 ameliorative and curative agencies, medicinal and others. 



The state known as fever, or pyrexia, being due to one 

 or more causes, the sources and nature of which it is 

 of the greatest importance to determine, let us endeavour 

 to give an example of our course of procedure in arriving 

 at a solution of the problem by the choice of the simplest 

 known example of the condition, viz. febricula. 



Febricula is a somewhat variable affection, both in its 

 intensity and duration, and arises, culminates, and declines 

 often, or generally, without the necessity for any interven- 

 tion or alarm ; being, consequently, not often seen, but 

 sometimes experienced by those competent to draw scientific 

 conclusions regarding it, convalescence ensuing through 

 the untrammelled and unadulterated operations of the vis 

 medicatrix nature. The disease is usually ushered in by 

 a more or less pronounced sense of " chill," succeeded by 

 a more or less sustained rise of temperature, with a 

 varying amount of functional or organic derangement 

 or disturbance, and is succeeded by a shorter or longer 

 period of recovery or convalescence. 



The sense of " chill " may be induced by the operation 

 of various causes, such as exposure to cold or wet, or 

 cold and wet, and consists of the excitation of the vaso- 

 motor nerve mechanism of the skin, with the contraction 

 of its muscular mechanisms, the closure of the ducts 



