DISEASES WHOSE CAUSE HAS NOT BEEN ISOLATED 185 



tern of certain peculiar bodies termed Negri bodies, after 

 Negri, the investigator who first observed them. The 

 presence of these bodies is considered pathognomonic 

 of the disease. Whether these bodies are micro-organ- 

 isms or products of the nerve-cells has not yet been 

 determined. 



Morbid Physiology. The alterations of function in this 

 disease resemble very closely those of tetanus, The 

 spasms of the muscles of deglutition are characteristic. 

 They are excited by attempts at swallowing or even the 

 thoughts of swallowing, being provoked by the sight 

 of water. It is from this peculiarity that the desease 

 derives its name. The virus is found in the spinal cord 

 and brain and is always present in the saliva. It 

 makes its way from the point of infection to the brain 

 and cord by way of the nerve-trunks, as in tetanus. 



YELLOW FEVER 



Definition. A fever of tropical and subtropical coun- 

 tries, characterized by jaundice, albuminuria, and a 

 tendency to hemorrhages of the stomach. 



Etiology. The micro-organism which causes this dis- 

 ease has not been isolated, but is known to inhabit the 

 blood of infected patients, as the disease has been pro- 

 duced by injecting the blood of those infected into 

 healthy individuals. The infection is transmitted from 

 individual to individual by the bite of certain species 

 of mosquito. This has been proved to be the only 



