156 THE SENSE OF TOUCH IN ANIMALS 



variability of the needs and lives of the animals presenting 

 them, calculated to subserve, in an important degree, the sense 

 of touch residing in the hand and foot. The areas of ridge- 

 covered skin between the primary pads before-mentioned, are 

 mostly covered with ridges of a simple transverse, oblique, or 

 longitudinal direction, but the pads (apical, interdigital, and 

 proximal) being primarily " buffers " in function, become more 

 and more important as sensitive areas in walking and prehension, 

 and on these arches, loops and whorls of the papillary ridges 

 become grouped with increasing complexity of pattern until 

 the hand of Man is reached. Here the highest development 

 is found, and in association with it the highest degree of dis- 

 criminative sensibihty. The view here maintained, and sup- 

 ported by the evidence of a large series of Mammalian hands 

 and feet, that whorls are a further development of loops, and 

 loops of arches, is unfortunately in direct contradiction to 

 the view of these patterns which Miss Whipple holds. She 

 says that the arrangement of ridges into a whorl (as it is here 

 called), constitutes the " typical pattern," and she finds this low 

 down among the Primates, as in Galago and Lemur, and on 

 p. 339 she gives a series of impressions from human finger-tips, 

 in which she endeavours to show the process of degeneration 

 from this typical pattern, the next stage being a loop, the next 

 a tented arch, and the final stage a simple arch. There is an 

 objection to this view of the degeneration of patterns from 

 the whorl to the loop, and the loop to the arch, which Miss 

 Whipple's own study of the Mammahan pads brings out with 

 fatal clearness, but which her own limited series of drawings 

 of the whole hand and foot fails to show. As before stated, 

 Miss Whipple lays much stress on the division of pads into 

 primary and secondary pads, the former group bemg apical, 

 interdigital, and proximal. She and Dr. Wilder trace certain 

 Mnes either of ridges or rows of epidermic warts round these 

 primary pads in a certain constant form, and they point out 

 that each t3rpical pad has its three triradii. In lower Mammals 

 which have no epidermic warts or ridges, such as Microtus 

 agrestis, these are foreshadowed by tri radiating arrangements 



