CHAPTER IX. 



Natural Selection {continued) — The Necessarily -fatal Environment. 



When treating of natural selection it was found advisable to 

 divide the different varieties of E into two classes — namely, 

 those to which the human organism is adaptable, and those 

 to which it is not. The latter class was spoken of as the 

 class of " necessarily fatal " E's, inasmuch as such E's necessarily 

 lead to destruction, and it is this class that we may now with 

 advantage consider at greater length. As regards many forms 

 of E, such as poisons and violence, their necessary fatality is 

 at once obvious; but besides these there are others, which, 

 although not necessarily fatal to the individual in the sense of 

 causing more or less immediate death, are yet necessarily in- 

 jurious to him, and " necessarily fatal " to racial life, or, 

 perhaps I ought to say, family life. By this I mean that, if 

 successive generations of the same family be reared amid 

 such E's, a total extinction of the family will sooner or later 

 follow. 



Now the number of these forms of necessarily fatal E is 

 exceedingly great in a civilized community, far greater indeed 

 than mere casual observation would lead us to think. We may 

 lay down the broad rule that (other things being equal) the 

 E of any given individual is healthy in proportion as he lives in 

 the open air, and exercises therein ; and contrariwise, the E is 

 unhealthy in proportion as his life is spent in confinement and 

 muscular inactivity. Civilization entails much indoor confine- 

 ment, and herein lies, I believe, its chief evil. It is probable 

 that all occupations which necessitate prolonged confinement 

 from a tender age upwards, whether in town or country, are 

 necessarily fatal, and certainly all those are which prevent 

 the enjoyment of fresh air and proper bodily exercise from 

 time to time. But, apart from the injurious effects directly 



