THE CAUSATION OF DISEASE. 1 6$ 



f S 5 + E d = 



9 S 4 + E 7 = 



h S 3 + E 8 = 



i S 2 + E 9 = 



3 8, + E 1§ = 



(An individual in whom the largest k S + E, = 



quantity of specific pathogenesis is 



unable to induce the disease.) 



In the first case (a), the inherent tendency is represented by 

 ten and the E by one. In such a case the disease breaks 

 out spontaneously, i.e., is fully inherent, for it occurs under the 

 most favourable E possible. It is necessary to represent this by 

 the number one, because we can never entirely eliminate the E, 

 seeing that disease is an inter-action of S and E. In the last 

 case (k), the largest quantity (ten) of specific pathogenesis, that 

 is, the most intense disease-producing E, is unable to excite 

 the disease ; the S totally refuses to respond morbidly in the 

 specific way, and the inherent tendency may therefore be 

 represented by o. 



Let us apply this numerical method to illustrate the share 

 in causation taken by S and E respectively in a particular 

 disease — e.g., insanity. " It must be borne in mind,'' says 

 Maudsley, speaking of the causation of insanity,* " that 

 hereditary predisposition may be of every degree of in- 

 tensity, so as, on the one hand, to conspire with certain more 

 or less powerful exciting causes, or, on the other hand, to 

 suffice of itself to give rise to insanity, even amidst the most 

 favourable external circumstances." Let us endeavour to give 

 numerical expression to these words of Maudsley. The formula 

 S, + E 1 signifies that, under the most favourable E, the indi- 

 vidual will become insane; S 9 + E l5 that, with the greatest con- 

 ceivable care, the disorder may be averted. In the latter case 

 it would be necessary to protect the individual from a long 

 array of influences; for there are many diverse circumstances 

 included under the specific pathogenesis of insanity, such as 

 mental excitement or shocks, child-bearing, fevers, and indeed 

 anything and everything which tends to reduce the bodily 

 nutrition, be it bad air, improper or deficient food, lack of 

 exercise, or what not. It would, indeed, be impossible to 



* "A System of Medicine," edited by J. Russell Reynolds, M.D., &c, p. 13. 



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