THE CAUSATION OF DISEASE. 2 J 



causes no pain. The pain in cortical disease is probably due to 

 involvement of the meninges — at all events, experimental 

 injury to the cortex causes no pain. Among symptoms due 

 to primary mal-E, the swelling of typhlitis, the eruption of 

 scabies, and traumatic haemorrhage may be instanced. 



When in any given case of disease we have observed all the 

 symptoms, they are to us so many marks of morbid action ; and 

 it is then our duty to put each in its proper place in the chain 

 of morbid action. In most diseases this chain is so complex 

 that it is often very difficult, and sometimes quite impossible, to 

 work out the puzzle. But this should always be our aim, and 

 we should above all endeavour, by the aid of the symptoms, to 

 determine the primary link. When we cannot do this, we must 

 seek for the nearest attainable. For example, a patient suffers 

 from cerebral tumour, but presents no other symptom than 

 hemiplegia, we cannot in such a case refer the hemiplegia to 

 anything behind it — this is the most remote link discoverable 

 — and, though really a symptom of something else, it is raised 

 to the full dignity of the substantive disease. If, how- 

 ever, the tumour be afterwards diagnosed, the disease is 

 no longer styled hemiplegia, but cerebral tumour ; and thus, 

 when we travel backwards, link by link, to the primordial 

 one, the disease of to-day may become the symptom of the 

 morrow. 



This seems a fit place to say a few words on the subject of 

 nosology. The nomenclature of disease is not based on one, 

 but on several methods, (i) The most obtrusive symptom 

 may be signalled out, as in scarlatina, small-pox, con- 

 sumption ; (2) the mal-E, if very obvious, may serve to 

 designate the malady, as in tapeworm, sun-stroke; or (3) the 

 disease may be named after its discoverer. This last method 

 is probably the most objectionable of all. It would be difficult to 

 find a common basis of nomenclature ; in regard to diseases 

 beginning locally, we should, I think, where possible, choose a 

 term which shall not only specify the tissue primarily affected, 

 but shall also indicate, as far as possible, the nature of the 

 morbid process — e.g., rheumatic mitral endocarditis, mammary 

 carcinoma, puerperal peritonitis. It matters little, however, 



