RII^q^DERPEST, 



ITS HISTORY, PATHOLOGY AND TREATMENT. 



Diseases of animals are either epizootic or enzootic. This 

 classification corresponds to that of the maladies which affect 

 the human race, epidemic and endemic. 



The former of each class have been defined as dependent 

 upo7i or originating in some particular condition (constitu- 

 tioseris) of the atmosphere, and as attacking a nuniber of indi- 

 viduals at the same time. Thus they differ from the latter 

 of each class, which are described as of purely local origin, 

 at least in the first instance, and as comparatively limited or 

 isolated in their development. 



Diseases, however, that are at first endemic or enzootic, 

 may break out at a time when their diffusion is favored by 

 currents of the atmosphere ; when its condition by lowering 

 the tone increases the susceptibility of the patient ; or when 

 chemical or other changes affect its normal constitution, and 

 so develop fresh food for the local malaria. Then, these dis- 

 eases become epidemic or epizootic. 



Most of such diseases exhibit this further peculiarity of de- 

 veloping in their course a malignant virus or miasm (per- 

 chance infinitesimal germs, with all the subtle rancor and 

 prolific power of a fungous growth), which spread through 

 or float on the atmosphere, intensifying the original power of 

 the " materies morli,^^ whether originally local or not, and 

 thus these maladies are infections. But frequently it happens 

 that the poison may be propagated by touch or direct applica- 



