Introduction to the Study of Disease 



animal ; through sponges ; drinking water ; food ; 

 feeding-troughs ; stable appliances, such as brushes, 

 etc. Such transference may be direct or indirect. 

 When the virus is swallowed it belongs to the 

 former category ; but when implanted into the 

 system, by some mechanical means, it constitutes 

 indirect transference. The term infective is 

 preferable to the usage of contagion, because it 

 implies all methods of the transference of disease, 

 whereas contagion ought to be limited to disease 

 communicated by contact, not necessarily with the 

 individual, but likewise through the medium of 

 some agent infecting it. 



Mange and Ringworm are both contagious 

 diseases, but they are also infective. Another 

 drawback to the use of the term contagious is 

 found in its inapplicability to such maladies as 

 Swine Fever, Rabies, Anthrax, Tetanus, Actiono- 

 mycosis, etc., all of which are, more correctly, 

 designated innoculable diseases — a term that at 

 once expresses the method of transference. The 

 foregoing distinction concerning a class of diseases, 

 sometimes spoken of as zymotic, has been given in 

 order that the reader may be in a position to 

 correctly appreciate the differences between the 

 multifarious specific ailments he may come across 

 affecting animals, or more correctly the channels 

 by which they are distributed. 



The different species of domestic animals behave, 

 when labouring under diseases, in divers manners ; 



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