306 THE CAUSATION OF DISEASE. 



Let us now consider each of these three classes separately. 



I . Diseases in which there is obvious Structural Abnormality. 

 — As an example of these we may instance the inflammations 

 which play such a large part in disease. In these cases the E 

 acting upon the S produces obvious abnormality in structure. 

 Such a pronounced structural change implies disease, but it 

 must be carefully borne in mind that a distinct and marked 

 structural abnormality may exist without giving rise to any 

 symptoms — to wit, patches of atheroma, miliary aneurisms, 

 deep-seated tumours, and many other gross structural changes. 

 It would be a great mistake to suppose that disease necessarily 

 exhibits symptoms, or that the presence of these is the test and 

 criterion of disease. The symptoms of disease are only the 

 evidence of it to be got during life, whether by altered function 

 or otherwise, and that evidence may not be forthcoming ; and 

 this for two reasons — first, because it is sometimes from its very 

 nature undiscoverable (as may happen in atheroma) ; and 

 secondly, because of failure on our part to detect the discover- 

 able— i.e., that which by a fuller development of human 

 resource might be discovered. 



Be it noted, in respect of such non-symptomatic disorders, 

 that the potential germ of symptomatic disturbance resides 

 within them, and further that all such cases are covered by the 

 definition of disease already given — viz., that it is abnormal 

 inter- action between S and E. These non-symptomatic 

 disorders are in a large measure localized — that is, they lead 

 to a very slight secondary mal-E. In the site of an athero- 

 matous patch an abnormal inter-action between S and E has 

 been going on from the earliest date of the disease. It might 

 be urged that an atheromatous patch, when it arrives at its 

 final stage of calcification, would not, according to this defini- 

 tion, constitute disease, seeing that little or no inter-action of S 

 and E would then be taking place. This is, however, no 

 cogent objection, for it is evident that there is not taking place 

 in the particular part of the body where the patch is located 

 that inter-action of cell and cell-E which constitutes health. 

 It is quite obvious that, if there is no inter-action at all, there 

 is interference with proper inter-action. 



If, however, exception be taken to this mode of argument, 



