14 Veterinary Medicine. 



The terms enthetic, zymotic, and contagious best express 

 modern views of the nature of these maladies. The terra infec- 

 tious when used to express a gaseous or otherwise intangible 

 (unorganized) body, or influence transmitted through the air, 

 necessarily excludes the particulate, living, self-propogating germ 

 upon which the transmissibility of the disease depends. A chem- 

 ical, electrical, or other body or influence generated outside the 

 animal body, cannot well be conceived of as reproducing itself 

 within the animal body but must act like any other ectogenous poi- 

 son, according to the size of the dose and the frequency of its ex- 

 hibition. This might create an enzootic disease but would lack all 

 the qualities of a contagious affection since it could not spread 

 from a victim when taken elsewhere and turned among animals 

 which would prove equally susceptible if placed within the infect- 

 ing area. Suppose on the other hand we apply the term infectious 

 to diseases in which the levity of the particulate living germ al- 

 lows of its being inhaled into the body of the susceptible animal, 

 the case becomes one of simple mediate contagion, the air acting 

 as the intermediate bearer. 



The term zymotic conveys a clear idea of the method of in- 

 crease of the disease germ in the body by the ordinary process of 

 generation. The old doctrine of fermentation by a continuous 

 change, due to contact with dead fermenting matter, as an inflam- 

 mable body continues to burn by contact with the incandescent 

 portion, has been definitely disproved by the investigations of 

 Pasteur and others, and today we must recognize that every fer- 

 mentation is the result of the propogation and vital activity of 

 living organisms. This does not ignore that the chemical prod- 

 ucts or enzymes which are constructed by the vital activity of the 

 microbes, will dissolve or transform organic matter, but in the 

 absence of the microbe no such enzyme can reproduce nor mul- 

 tiply itself and its action must therefore be exactly limited by its 

 amount. The living germ itself is therefore the one effective fac- 

 tor, by which the contagious disease may be maintained and 

 propagated. In its turn the living germ can only come from a 

 pre-existing living germ. To the scientist of today the doctrine 

 of spontaneous generation is a thing of the past and the aphorism 

 omnis ovum ex ovo is dominant. The argument drawn from the 

 saccharizing of starch in the germinating seed by the operation of 



