21 8 THE CAUSATION OF DISEASE. 



generation, but, if successive generations of the same family 

 thus inordinately indulge themselves, complete family extinc- 

 tion must sooner or later result. Let any one glance around 

 and he will see the truth of this : not only will he find isolated 

 individuals, young and old, thus destroying themselves, but he 

 will discover whole families on the rapid road to extinction. 



In this way there is a perpetual weeding- out of those 

 mentally incapable of resisting certain pathogenic E's, and be 

 it remembered that this result lies chiefly with the individual ; 

 its cause is structural, and due to some deficiency in the brain 

 cortex. I say the result lies " chiefly " with the individual, 

 because we must take into account the amount of pathogenic 

 E to which he is exposed. Some are carefully sheltered from 

 injurious moral influences ; others are brought up in a very 

 hot-bed of immorality; and if the one escapes unhurt, while 

 the other falls, it is not necessarily because the former pos- 

 sesses greater resisting power. Nevertheless, the element of 

 individual resistance must be taken into account. A member of 

 a civilized community has to contend against certain mal-E's, 

 and, if he cannot resist their evil influences, he is weeded 

 out, being, in fact, structurally unfit to cope with his E. Drink 

 is a more terrible poison than any zymotic virus — a more 

 deadly enemy than the most powerful armies, and he who 

 cannot withstand its alluring influence — he who cannot with- 

 stand the mal-E, " Drink" — alike with him who is incapable 

 of resisting the evil effects of the ague or typhoid poisons, 

 succumbs to the inexorable law of natural selection, and in 

 this way adaptation to the complex E of a civilized community 

 is perpetually going on. 



I do not for one moment wish to suggest that this weeding- 

 out process should be allowed to run its course unchecked. It 

 is the duty of those in authority to render the E as harmless 

 and innocent as may be, to bring up children in a beautiful 

 morality, and to so strengthen the mental self, that the indi- 

 vidual may escape unhurt from the many moral evils which in 

 spite of care must always surround him. 



So much for the actual weeding-out process, but, as already 

 observed, natural selection also operates upon the mental side of 

 man without directly leading to actual destruction of life — 



