i68 Temperature Disturbances. 



or partial inaiii testation of a complex reaction to which the or- 

 ganism is prompted by the invasion of substances foreign to the 

 system. From this it may be appreciated that the idea of febrile 

 temperature and of fever is in reality principally based on the 

 aetiology of the condition ; the existence of proper causes of fever, 

 the presence of pyrogenetic substances, is the factor determining 

 whether we are or are not to regard and speak of a hyperthermia 

 as febrile. 



Microorganisms, both vegetable and animal, constitute a most 

 important group of these pyrogenic substances, acting especially 

 through their chemical toxic products. It is this fact which ex- 

 plains why the course of nearly all the acute infections is accom- 

 panied by fever. It can be promptly induced by infection with 

 various specific germs ; inoculation with anthrax bacilli or pyogenic 

 cocci, with trypanosomes or piroplasmata, each occasions a febrile 

 reaction. After Charrin and Ruffer pointed out that, by injecting 

 into rabbits cultures of bacillus pyocyaneus which had been 

 sterilized and freed from living germs, febrile temperature acces- 

 sion ma}' be induced, a number of observers have demonstrated 

 that similar effects may be obtained by employing the metabolic 

 products of a number of other bacteria. This means therefore 

 that we are here dealing with a group of soluble substances passing 

 from the substance of the microorganisms into the fluids and tissues 

 of the affected body, either secreted by the living bacteria or 

 representing some of the results of disintegration of the bacterial 

 body (toxines, proteins, alkaloids and a variety of substances of 

 different composition). According to E. Centanni, practically the 

 entire group of bacteria produce a practically uniform fever toxine 

 which he isolated from cultures and named pyrotoxina bacteritica, 

 and with which he was able to reproduce in rabbits all the main 

 clinical features of the infectious fevers. 



This thermotoxine is, however, produced in varying quantity 

 by the individual types of bacteria ; injection of definite doses of 

 some forms of bacteria and culture filtrates occasioning no febrile 

 reaction ; some only after large doses ; others causing high fever 

 with the employment of extremely small amounts. Another 

 feature to be considered is that various kinds of bacteria known 

 to elaborate thermogenic substances do not act with uniformity 

 in the production of fever in all kinds of animals, and different 

 animals show even less uniformity in their susceptibility to the 

 fever toxines (Krehl) ; from which it may be assumed that the 



