120 NATURAL INHERITANCE. [CHAP. 



occurrences, namely that in which the mediocre members 

 of a population are those that are most nearly in 

 harmony with their circumstances. The harmony ought 

 to concern the aggregate of their faculties, combined 

 on the principle adopted in Table 3, after weighting 

 them in the order of their importance. We may deal 

 with any faculty separately, to serve as an example, if 

 its mediocre value happens to be that which is most 

 preservative of life under the majority of circumstances. 

 Such is Stature, in a rudely approximate degree, inas- 

 much as exceptionally tall or exceptionally short persons 

 have less chance of life than those of moderate size. 



It will give more definiteness to the reasoning to 

 take a definite example, even though it be in part an 

 imaginary one. Suppose then, that we are considering 

 the stature of some animal that is liable to be hunted 

 by certain beasts of prey in a particular country. So 

 far as he is big of his kind, he would be better able 

 than the mediocrities to crush through thick grass and 

 foliage whenever he was scampering for his life, to jump 

 over obstacles, and possibly to run somewhat faster 

 than they. So far as he is small of his kind, he would 

 be better able to run through narrow openings, to 

 make quick turns, and to hide himself. Under the 

 general circumstances, it would be found that animals 

 of some particular stature had on the whole a better 

 chance of escape than any other, and if their race is 

 closely adapted to their circumstances in respect to 

 stature, the most favoured stature would be identical 

 with the M of the race. We already know that if we 



