PALM AND SOLE nfl'HESSIONS. 395 



111. Tlic jiiiliii (iiid .sole .syslfiii. 

 The method which it is tlie purpose of this paper to advocate and 

 briefly exphiin is closely allied to that of Mr. Galton and is, in fact, 

 an extension of his system to the -palmar and flantar surfaces, which 

 are covered with the same sort of ridges as are the finger tips and in 

 ■wliich the variation is greater and the details larger and more ohvious. 

 A moment's inspection of a human hand and foot will show that the 

 entire ventral surface of each, including that of the digits, is covered 

 by a peculiar sort of skin, very different from that found elsewhere, 

 and that along the sides of the palm and the digits, and just above 

 the sole upon the foot, there are definite lines of separation between 

 them and the normal skin, which in the hand corresponds in general 

 position to the seam in a glove which unites the upper and under sur- 

 faces. This palmar and plantar skin differs from that of the rest of 

 the body in many ways. It is absolutely hairless and at no time 

 during embryonic life shows indication of either hairs or hair fol- 

 licles. It consequently has no power of forming goose-flesh when 

 chilled, although the back of the hand and the surface of the forearm, 

 in the immediate vicinity of the palm, are favorite places for the dis- 

 play of this phenomenon. It is also very slightly, or not at all, pig- 

 mented as is readily seen by inspection of the palms and soles of a 

 negro, and consequently does not tan or freckle, a distinction often 

 made very obvious by a comparison of the back of the hand with the 

 palm. The most obvious character, however, and the one which 

 directly concerns both Galton 's system and the one advocated here, is 

 that of the small but distinct epidermic ridges, which cover the surfaces 

 in question. These may be said to run in a general way parallel to one 

 another and diagonally across the palm or sole, although in certain 

 regions their direction is altered and at more or less definite places 

 they form curiously disposed patterns, usually in the form of loops or 

 spirals. With a moderate lens these ridges give the skin an appearance 

 much like that of corduroy and there may be seen running along the 

 middle of each ridge a row of minute indentations or pores, at about 

 equal distance from one another, the orifices of the perspiratory glands. 

 Running over and across these ridges in directions which bear no rela- 

 tion to them are the wrinkles or ruga, more abundant in the hand than 

 in the foot, and caused by the various motions of the digits and of the 

 other movable parts of the member. Those seem at first especially 

 obvious and interfere more or less with the study of the ridges, but a 

 little practice will enable one to ignore them altogether. In printed 

 impressions, which are used for purpose of study far more than are the 

 actual surfaces, most of these are pressed out of existence while the 

 remainder appear merely as narrow white streaks which do not affect 

 the investigation (see Figs. 1 and 2). 



