PALM AND SOLE STUDIES. 



whorl into a loop, ulnar or radial in accordance with the triradius 

 that is suppressed; and this figure in turn becomes an arch by the 

 suppression of the remaining triradius. The low arch, without 

 appreciable core, is thus the final stage in the reduction process 

 of a finger pattern. The fact that all possible stages along several 

 lines of degeneration are found in man indicates the reduction in 

 functional value as friction organs of these once so vital parts. 



The six patterns of the palm proper consist of the four inter- 

 digitals, lying just proximal to the intervals between the fingers; 

 the thenar, and the hypothenar. Of the four interdigitals the 

 first (at the radial end of the series) lies below the wide interval 

 between thumb and index finger, and is found usually in close 

 connection with the thenar, the tw T o forming loops opening in 

 opposite directions, and with two triradii between them. This 

 pattern-complex is rare in the white race; but much more frequent 

 in some others (e. g., the Maya-Quiches of Yucatan; Wilder, 

 1904). The three remaining interdigitals appear below the finger 

 intervals, the second lying between triradii A and B, the next 

 (third) between B and C, and the fourth between C and D. The 

 one between triradii A and B (second) is the rarest of the three 

 and the fourth, between C and D, is the commonest. Further- 

 more, this last is frequently provided with a triradius of its own, 

 aside from C and D, a peculiarity occasionally, but not so fre- 

 quently, met with in the other cases. The third pattern, between 

 B and C, is liable to be confused with a "false pattern" caused by 

 certain configurations of the ridges of the palm, but easily dis- 

 tinguished from the real one by its position in a depression rather 

 than on an elevation (Whipple, 1904). The three mounds of 

 this region are easily seen in most hands by bending the fingers 

 back and looking across the palm in various directions. They 

 are the plainest in children and in the fetus they are often ex- 

 tremely conspicuous (Retzius, 1904). 



As might be expected, a human hand presenting all eleven 

 patterns is quite rare, yet does occur. Such a case, found in the 

 right hands in twin boys, has been already figured and described 

 by the writer. 1 



As each of the four interdigital pads (or patterns) possesses 

 typically three triradii of its own, with four for the third, it is 



1 Wilder, A-nat. Anz., Bd. XXXII. , 1908, pp. 194, 195. 



