THE CIRCULATORY APPARATUS. 269 



be reproduced by inoculation, there resulted a febrile reaction, 

 which could only be attributed to chemical poisons called 

 ptomains or toxins the result of the growth of the bacteria. 



These chemical substances may be the product of organisms 

 which are not capable of existing in the living body, but only 

 in dead vegetable or animal tissues i. e., saprophytic bacteria, 

 to which class belong the poisonous alkaloids which have 

 been isolated from putrefying fish, meat, sausage, cheese, etc. 

 But of far greater clinical importance in the etiology of 

 fever are the products of pathogenic bacteria. 



Undoubtedly febrile rise of temperature may be produced 

 by other agencies, such as fear and affections of the nervous 

 system ; but here grave functional and anatomical disturb- 

 ances are entirely absent. 



The significance of fever is not known, though modern ex- 

 perimental evidence supports the theory that it is a conserva- 

 tive effort on the part of nature to combat the noxious sub- 

 stances which give rise to it. In animals rendered hyperther- 

 mic by external heat or cerebral puncture and inoculated with 

 various organisms pneumococcus and others the increase 

 in body-temperature seemed to exert a most favorable influ- 

 ence on the course of the infection. 



The anatomical changes in fever, due to the increased tem- 

 perature alone, are few. It is difficult to separate the results 

 produced by the high temperature from those produced by its 

 exciting cause. Cloudy swelling and fatty degeneration of the 

 heart, liver, and kidneys, are probably in part due to the fever 

 itself, though in part undoubtedly to toxic substances circu- 

 lating in the blood. 



THE CIRCULATORY APPARATUS. 



Hyperaemia is an increase in the amount of blood in a part : 

 and is either actual, due to an increase of the flow to the 

 part ; or passive, due to an obstruction of the outflow. 



Active hyperaBmia : Blushing is a physiological example. 

 Pathologically it is hardly met except associated with some of 

 the phenomena characteristic of inflammation. A variety 

 due to vaso-motor paralysis, as seen in experimental section of 

 the cervical sympathetic in animals, is occasionally met with 

 clinically, as after gunshot-wound of the same nerve. 



