268 PATHOLOGY OF THE BLOOD AND PECULATION. 



changes in various tissues likewise accompanying these phe- 

 nomena all of which are included in the clinical term fever. 



Rise of body-temperature is the most essential phenomenon 

 to the existence of fever. 



The normal constant temperature of the body depends on 

 an equilibrium between the processes of heat-production and 

 heat-dissipation, which is maintained through the influence 

 of the nervous system ; the exact nature of this mechanism, 

 however, is not yet fully understood. In fever this equilib- 

 rium is disturbed, so that the processes of heat-dissipation 

 and heat-production do not bear a normal relation to each 

 other. 



Etiology : Clinically fever has been observed to follow con- 

 siderable extravasations of blood ; experimentally it occurs 

 after transfusion of blood from one animal to another and 

 also after intraperitoneal injections of blood. 



The demonstration of the fibrin-ferment as the pyogenic 

 substance capable of exciting such a rise of temperature 

 suggested the investigation of other ferments, and it was 

 found that the intravenous injection of pepsin, trypsin, and 

 papoid produced a well-defined fever. This type of fever 

 corresponds to that observed by surgeons after extensive 

 aseptic wounds, as a subcutaneous fracture, the pyogenic 

 material resulting from the disintegration of the injured 

 tissues. 



Most morbid processes with which fever is associated are 

 due to micro-organisms, and it is consequently quite natural to 

 turn to these elementary forms of vegetable life in endeavor- 

 ing to elucidate this subject. Early investigators, less than 

 fifty years ago, demonstrated that injections of putrefactive 

 materials into the blood of animals were capable of producing 

 marked febrile reactions, and a knowledge of the part played 

 by micro-organisms in the production of putrefaction made 

 quite evident the importance of their rdle in fever. 



In 1863 Davaine described a rod- shaped organism in the 

 blood of animals sick with splenic fever, and found that in a 

 healthy animal, if inoculated with the blood of an animal so 

 affected, the disease was reproduced. Subsequently Pasteur 

 showed that if these organisms were removed by filtration 

 through earthen cylinders, though the disease could not then 



