THE PHYSIOLOGY OF THE SENSE OF TOUCH 143 



morphology in a very complete manner, and their homologies in 

 numerous groups. It is impossible, briefly, to summarise so long 

 a paper, but it may be stated here that she discards the term 

 papillary ridges in favour of " epidermic ridges " and calls the 

 skin on which these are found " friction-skin." She finds 

 certain simple elements of which the developed ridges seem to be 

 formed and calls them " epidermic warts " and " epidermic 

 rings." These terms are in keeping with her main thesis, viz., 

 that the ridges in question are not, as hitherto thought, primarily 

 tactile structures, but that they are physiological adaptations, 

 by which the walking-pads become covered with a surface cal- 

 culated to prevent shpping either in walking or prehension, and 

 that the ridges have only incidentally acquired an important 

 tactile function. This paper of Miss Whipple's was published 

 in the year before Schlaginhaufen wrote a still more elaborate 

 memoir in Gegenbauer's Morph. Jahrbuch on the Hautleisten 

 St/stem der Primaten-planta which occupied about 220 pages 

 and was largely illustrated. This paper was written by him in 

 ignorance of the paper by Miss Whipple, and he deals with it in 

 a short appendix, and does not controvert to any serious extent 

 her views, except in the important point that he disagrees with 

 her claim that the functions of the papillary ridges are primarily 

 mechanical and only secondarily and incidentally tactile. 

 Certain conclusions of a physiological nature which he makes, 

 will be referred to later. 



This brief account of a matter, which has reached such large 

 proportions, will serve to show that the study of these minute 

 ridges on the palm and sole of mammals is a not unimportant 

 subject. 



The physiology of the sense of touch does not of necessity 

 mingle with the more controversial matters which Dr. Wilder, 

 Miss Whipple, and Herr Schlaginhaufen have debated. It may 

 be sound morphology, and probably is, to look upon the mam- 

 malian primary pads as essentially walking-pads, for they are 

 found low down in the scale of mammals as in Didelphys and 

 Microtus agrestis, where the act of prehension can hardly be 

 fulfilled at all, also in Cercoleptes caudivolvuliis, a very active 



