42 DISEASE. 



causes ; one that predisposes, and one that excites. Accord- 

 ing to medical logic, both must operate in the production of 

 disease : the part must be predisposed before the excitement 

 can take effect. There are many exceptions, however to 

 this rule. An excitant may (as in the case of a red-hot 

 iron) be so potent as to take effect under any circumstances ; 

 though, the effect will be greater under circumstances of 

 predisposition. On occasions it happens, that what at one 

 time is a predisposing cause, at another becomes an excitant ; 

 such is the case with vicissitudes of temperature ; peculiari- 

 ties in feeding ; irregularities in exercise, &c. Sometimes, 

 the exciting cause appears to be altogether wanting; at 

 least it is not discoverable ; in which case we are in the 

 habit of attributing to the disease a spontaneous origin : after 

 all, however, it seems but a tacit acknowledgment, that we 

 are in ignorance of its inward exciting cause; for, as in 

 physics so in medicine, where we see effects, we naturally 

 look for causes. 



A Classification of Exciting Causes has been made 

 into mechanical^ chemical, natural, and malignant. The 

 mechanical causes comprise blows, bruises, cuts, punctures, 

 wounds, and injuries. The chemical causes include escha- 

 rotics, caustics, blisters, irritants, &c. The natural causes 

 are vicissitudes of temperature, and irregularities in diet or 

 exercise. The malignant, are poisons of all descriptions : 

 the virus of glanders and farcy, and of rabies ; animal efflu- 

 via ; the poisons of venomous creatures ; and vegetable 

 poisons of all denominations. 



The Proximate Cause is the change in an organ wherein 

 the disease is seated, and on which its existence depends. 

 "When we speak of the nature or essence of a disease, we 

 speak of its proximate cCiuse. In a word, it is the disease 

 itself — it has nothing to do with cause. 



EORM AND PROGRESS OP DISEASE. 



The Form a disease assumes Avill appear to depend on 

 two leading causes : on the state of the system at the time 



