CHAPTER III. 

 FEVER— PYREXIA. 



DEFINITION. — Fever may be defined as a general, 

 systemic disease or symptom of disease, manifested by ele- 

 vation of the temperature, and characterized by increased 

 destructive metamorphosis, accelerated circulation, and dis- 

 turbed secretion. The latter is but a symptom of the former. 

 The word applies particularly to a more or less persisting 

 rise of temperature. 



ETIOLOGY. — The real cause of fever is an aberration 

 of the vital function that maintains the equilibrium between 

 heat-generation and heat-dissipation. This vital function 

 of heat regulation, which Warren named thermotaxis, main- 

 tains the temperature of all warm blooded animals at a cer- 

 tain point in spite of external influences, so long as the or- 

 ganism is in a state of health. Heat-generation is due to oxi- 

 dation or combustion in the tissues. The blood dumps oxy- 

 gen into the tissues and thus produces a chemical action 

 that ends with the casting off of carbonic acid. The chemical 

 change occurring between the introduction of oxygen and 

 the elimination of carbonic acid produces the heat. This 

 chemical change is, however, not the simple .combination of 

 oxygen with carbon and hydrogen. It is a complicated pro- 

 cess in which complex chemical molecules are disin- 

 tegrated. Heat generation is, therefore, the result of com- 

 plex chemical changes in the tissues produced by oxygen 

 being thrown into them by the blood. 



Heat-dissipation, or loss of heat, is caused by the expos- 

 ure of the blood to external cold in the superficial capillaries ; 

 by exposure of the blood to the inspired air in the 



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