THE PHYSIOLOGY OF THE SENSE OF TOUCH 155 



that the patterns of the palmar surface are much more simple 

 than those of the terminal phalanges, and that the latter are 

 more complicated in pattern than in any group below man ; 

 secondly, that the human foot is markedly more simple in its 

 patterns than the hand, and hers again, the plantar surface 

 is more simple than the digits. The complex patterns of arches, 

 loops, and whorls on the tips of the human fingers are developed 

 in a region, and in a part of that region where the need for not 

 shpping is reduced to a minimum, and in the palmar and 

 plantar surfaces, where the patterns are of the simplest, tlicre 

 is, at any rate, some need for the prevention of slipping m 

 prehension and walking. 



It is necessary to enter a httle into the controversial aspect 

 of the functions of the patterns of the papillary ridges, and 

 to point out the important fact that the theory of the ridges 

 and their patterns being adapted to minister to the sense of 

 touch, apphes more consistently to all the special areas which 

 may be chosen for study, than the theory of Miss Whipple that 

 they are arranged so as to be at right angles to the forces which 

 tend to produce shpping, or the resultant of those forces. In 

 any critical area of the palm or sole or digits where it is important 

 to avoid shpping, it is obviously more necessary still that an 

 accurate intimation should be conveyed to the central nervous 

 system by means of these delicate projecting tactile ridges as 

 to the direction and degree of muscular force required, than 

 that a mere mechanical contrivance, such as the string on the 

 handle of a cricket bat, should mechanically prevent slipping. 

 We see thus that complexity of pattern either on palm, sole, 

 or digits has an endless raison-d'etre in connection with varying 

 tactile needs, whereas the mechanical theory of Miss Whipple 

 finds itself in all manner of difficulties as indicated in certain 

 special cases, pp. 152, 153, and as can be gathered in many more, 

 if the whole series of hands and feet be studied from this point 

 of view. 



The position here adopted with regard to the meaning of 

 the patterns on the Mammahan palmar and plantar siu-faces 

 is that they are adaptations, with a variabiUty as great as the 



