422 THE SKLN T . 



be seen easily on the palm, whereon each raised line is 

 composed of a double row of papilla), and is intersected by 

 short transverse lines or furrows corresponding with the 

 interspaces between the successive pairs of papilla). Over 

 other parts of the skin they are more or less thinly 

 scattered, and are scarcely elevated above the surface. 



Fig. 1 10.* Fig. in.f 



Their average length is about -,-J-g- th of an inch, and at 

 their base they measure about -^4- -^th of an inch in diameter. 

 Each papilla is abundantly supplied with blood, receiving 

 from the vascular plexus in the cutis one or more minute 

 arterial twigs, which divide into capillary loops in its 

 substance, and then reunite into a minute vein, which 

 passes out at its base. The abundant supply of blood 

 which the papilla) thus receive explains the turgescence or 

 kind of erection which they undergo when the circulation 

 through the skin is active. The majority, but not all, of 

 the papilla) contain also one or more terminal nerve -fibres, 

 from the ultimate ramifications of the ciitaneous plexus, 

 on which their exquisite sensibility depends. The exact 

 mode in which these nerve-fibres terminate is not yet 



* Fig. 1 10. Papilla, as seen with a microscope, on a portion of the 

 true skin, from which the cuticle has been removed (after Breschet). 



t Fig. in. Compound papillre from the palm of the hand, mag- 

 nified 60 diameters ; a, basis of a papilla ; b, b, divisions or branches 

 of the same ; c, c, branches belonging to papillne, of which the bases 

 are hidden from view (after Kolliker). 



