234 



ADVANCED PHYSIOLOGY 



Cold Perceiving Areas 



The outer surface of the dermis, where it comes into con- 

 tact with the epidermis is not flat and smooth but shows 

 many small elevations, called papillae; the epidermis fits 



over these so that the two 

 layers dovetail into each 

 other; Fig. 112. These 

 papillse on certain parts 

 of the body, e.g. on the 

 palms of the hands, are 

 arranged in parallel or 

 concentric rows so that 

 they show through the 

 epidermis and produce 

 the fine lines which appear 

 on the tips of the fingers 

 and toes. 



Organs of Touch, Heat 

 and Cold. In these pa- 

 pillse, nerve endings 

 and blood vessels are 

 abundant, though the 

 same papilla does not 

 usually contain both. 

 Some nerve endings as- 

 sociated with touch and 

 temperature changes are 

 shown in Figure 112. A 

 number of endings in the 

 same region will perceive 

 only cold, others only 

 warmth; so that in general we may say that the whole 

 body is mapped out into " cold and warm spots "; Fig. 116. 

 The ends of nerves which are sensitive to touch are called 

 tactile corpuscles or end bulbs; Figs. 117 and 118. They are 

 of different shapes and extremely small, varying for the most 



Warmth Perceiving Areas 



FIG. 116. DIAGRAM 



Showing the areas on the back of the hand 

 that perceive heat and cold. The two figures 

 represent the same area, one figure showing 

 the cold and the other the heat perceiving 

 areas. (Goldschneider) 



End Bulb 



FlG. 



117. ONE OP THE END 

 OF TOUCH IN THE EYE 



(Dogiel) 



BULBS 



