174 



INITIATIVE IN EVOLUTION 



being fitted by a shoemaker with rude shoes or walking-pads for 

 the better locomotion on or under ground, or in the branches of 

 trees. These pads are projecting masses of hard fat with fibrous 

 tissue interspersed and they early become fitted or adapted to or by 

 the use to which they are put. It is impossible to suppose that 

 certain rudimentary pads are devised by selective processes prior 

 to the altered habits of walking of the animal that acquires them. 

 From the shoemaking point of view the fashion is rough and 

 generalised, and the changing habits of the animal adapt the shoe 

 by degrees to the function employed, much as many a private 



Fig. 76. — Foot of squirrel- 

 monkey. 



Fig. 77. — Foot of macaque. 



soldier knows to bis cost that he has had to adapt slowly and 

 painfully his army boot to his particular foot. This process in an 

 early pedestrian mammal involves the breaking up and limiting 

 of the rudimentary pads by sulci in the dense skin, and the process 

 of struggle and adjustment between the pads and their bordering 

 furrows issues in the characteristic flexure of each mammal. From 

 experiences in the human body one knows how easily fibrous 

 adhesions between the skin and deeper parts, notably in cases of 

 Dupuytren's contraction of the palmar fascia, are formed by close 

 apposition of the two layers. Such adhesion is precluded when 

 much movement of the part occurs, but ex-hypothesi the rudimentary 



