PALM AND SOLE STUDIES. 183 



although even here there is a well-known type, the "simple arch," 

 in which the original pattern is reduced to its lowest terms, and 

 shows merely the position, or "core" of the former pattern 

 without more than the last vestiges of a single triradius. On 

 the other hand, others, like the second interdigital of the hand, or 

 the thenar of the foot, are seldom found, and when they do occur, 

 it is usually in the form of a mere vestige, where the closer ap- 

 proximation, or the change of direction, of a few ridges, are the 

 only indication of the former presence of a pattern that has 

 become lost. 



Again, a given pattern, when compared in different individuals 

 in w r hich it occurs, may show every stage of degeneracy, from a 

 concentric whorl, the most complete and ancestral form, through 

 those showing the loss of one or more of the triradii, to a wholly 

 vestigial condition, where a scarcely perceptible disturbance in 

 otherwise parallel ridges is indicative of the last traces of its 

 presence. 



In this difference in the liability of occurrence of the different 

 patterns, and in the sort of pattern when it does occur, whether 

 more frequently a primitive Whorl or simply a vestige, we find a 

 perfect correlation with the physiological use of the region 

 involved. In general those patterns which are situated upon the 

 more prominent surfaces, and which are therefore more often in 

 contact with external objects, are far more constant in their 

 occurrence, and appear more frequently in the form of whorls, 

 than are those which, during the normal course of human activi- 

 ties, lie in more retired spots, and are somewhat more shielded. 

 Whorls are, for instance, by no means uncommon on the finger- 

 balls, where a pattern of some sort is seldom entirely lacking, 

 precisely upon those surfaces which are subject to the most wear 

 and tear, and which press the most constantly upon external 

 surfaces; while the four interdigitals are far less constant, and 

 among these the second interdigital, especially protected both by 

 the activity of the thumb, and by that of the cooperating index 

 finger, seldom appears. On the foot the most common place for 

 a whorl is upon the ball of the great toe (the first interdigital 

 pattern) which bears the weight of the body at each forward step, 

 and in the bare foot is constantly in contact with the ground. 



