1 64 THE CAITSATIOX OF DISEASE. 



will produce practically the same morbid action in all, but this 

 is not true of a foul atmosphere, which will tend to induce 

 several distinct disorders, according to several distinct struc- 

 tural proclivities, or, as I have called them, deficiencies. 



Between the above two extremes of absolute impunity 

 from a particular disease, and absolute inability to escape 

 therefrom, there is a long series of fine gradations. An 

 individual may, in fact, have any shade of structural 

 deficiency, or tendency towards a particular disease, from 

 absolute security to impossible escape. This fact may be 

 well illustrated in the case of insanity. Some there are who 

 will not lose the even balance of the mind under the most 

 dire provocation. Let them be subjected to the rudest mental 

 shocks, the sharpest pangs of grief, the insidious torment of 

 worry, the wear and tear of excessive intellectual toil, or any 

 mental agitation whatsoever — the mind still pursues the even 

 tenor of its way. But there are others in whom the slightest 

 disturbance is sufficient to upset the mental balance, who will 

 become insane even though every possible care be taken to 

 guard them from exciting influences ; and between these ex- 

 tremes we can fill up a long series of fine gradations needing 

 an ever-increasing quantity of specific pathogenesis to call 

 forth the disorder. By a specific pathogenesis I mean such 

 E as tends to call forth a particular disorder, and it is impos- 

 sible to enumerate all the various forms of E which would 

 tend to excite into actual being an insane proclivity. 



Now, cau we in any way symbolize the relative share 

 taken by S and E in the causation of disease ? Let us 

 suppose a given disease to be made up of eleven units, and 

 let the share in causation taken by S and E respectively be 

 represented by any number from one to ten : it would be 

 manifestly incorrect to assign the full number (eleven) to 

 either, seeing that neither S nor E alone can constitute dis- 

 ease. Then, inasmuch as S-f E = the disease, we may arrange 

 the following table : — 



(An individual in whom the disease bursts a 

 out spontaneously). 



