484 



PHYSIOLOGY 



CHAP. 



particularly of the papillary layer, when we corne to study the 

 skin as the seat of the special senses. Here it is enough to say 

 that the depressions between the papillae are filled by cells of the 

 Malpighian layer, which is therefore thicker at these points. The 



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FIG. 132. Compound papillae from the palm of the hand. (Kdlliker.) 60 diameters, a, basis of a 

 papilla ; b, b, divisions or branches of the same ; c, c, branches belonging to papillae of which 

 the bases are hidden from view. 



surface of the epidermis is also uneven, and presents prominences 

 and depressions at a number of places, corresponding with the 

 position of the papillae or interpapillary spaces. These prominences 

 are termed the papillary ridges of the epidermis. 



In many parts of the skin, particularly on the palmar surface 



Fir,. 133. Linear sweat prints from palmar surface of finger (Aubert's photographic method). The 

 white line marks the papillary ridges, forming a vortex at the tip ; the black lines are the 

 furrows which lie between the crests. 



of the hand and fingers, the papillae of the corium are compound, 

 i.e. cleft at the summit into two or more secondary points, which 

 are ranged in lines separated by superficial furrows (Fig. 132). The 

 surface of the cuticle which covers these papillae shows ridges 

 separated by characteristic curved lines, which form a sort of 

 vortex at the culminating point of the digit (Fig. 133). Under a 



