156 INITIATIVE IN EVOLUTION 



why and wherefore of the strange skin of the hands of the slow 

 loris previously referred to. And if he be disposed also to the 

 pleasant pursuit of moralizing at the expense of others he will feel 

 led to reflect over harshly on the invalid and compare her outlook 

 on life with that of the loris. Even in this concrete case of the 

 hand of an invalid there may be evidence of positive as well as 

 negative response, if one examines the right forefinger so much 

 used in sewing, where the skin becomes hard and thick. 



The foot of man has a good deal of negative evidence in favour 

 of my contention as well as positive. As to the latter, in the 

 thickening of tbe skin over the heel and ball of the great toe in those 

 who walk much we find changes precisely similar to those on tbe 

 hand. The negative or degenerative changes visible on man's 

 foot consist chiefly in the remarkable simplicity of pattern of the 

 papillary ridges as well as their flattening and blurring, through 

 wasting of those which occupy mainly the arch of the foot. These 

 will be shown in the next chapter in a drawing. When this portion 

 of skin is compared with that of the foot of any monkey or anthro- 

 poid ape it is clear that in this respect the skin of man's foot has 

 undergone even more degeneration than his hand has shown of 

 higher development. This degeneration has coincided with two 

 facts, first that man's terrestrial locomotion has advanced far beyond 

 that of any other Primate, and second, that he alone has a plantar 

 arch. This subject belongs to a later chapter and is referred to 

 here because the possession of an arch to his foot has caused man 

 to escape, on the under surface of it, a vast proportion of the stimuli 

 of pressure and friction involved in his mode of walking, and the 

 extreme simplicity of his plantar papillary ridges, and relatively 

 thin, soft skin under the plantar arcbes affords a fairly conclusive 

 example of change of structure from disuse per se. 



I have thus only selected and used two striking types of the 

 Primates, the loris and man, not wishing to burden this part of the 

 subject unduly with intervening and less characteristic forms of 

 life. It may be legitimate here to say in defence of this long chapter 

 that it illustrates what I desire to keep before me all through, the 

 fact that use, habit, environment and selection go ever hand in 

 hand. In all matters of science one has to descend to particulars, 

 so it seemed necessary to select a few scattered phenomena in the 

 best known groups of higher animals and endeavour to understand 

 how certain " characters " or better " modifications " began to 

 grow big enough to avoid passing through the meshes of the sieve. 



