i CUTANEOUS SENSIBILITY 39 



Left thigh, anterior surface, about 1 cm. from edge of patella . . 2-87 



Back, middle line, level of ant. sup. iliac spine . . . . .3-13 



Left forearm, middle of flexor surface 3-22 



Thorax, left axillary line between xiphoid process and umbilicus . . 3-25 



Thorax, middle line, level of 2nd intercostal space . . . .3-85 



Left wrist, stiloid process of ulna . . . . . . . .4-10 



Thorax, middle of axillary line, level of 5th intercostal space . .4-15 



Thorax, middle line, level of 4th intercostal space . . 4-35 

 Dorsum of left foot, middle 



Sack, middle line, level of 3rd dorsal vertebra 

 Thorax, middle line, level of 5th intercostal space . 



Left wrist, radial surface 



Left wrist, dorsal surface, middle line 



Left wrist, flexor surface, 2-7 cm. from the fold 



Back, level of 7th cervical vertebra 



4-75 

 4-75 

 4-95 

 5-15 

 5-60 

 5-70 

 6-35 



Comparison of these tables shows that the two factors on 

 which the pressure sensibility in the different regions of the skin 

 depends (the mean liminal value and the number of tactile points 

 in the surface unit) are more or less compensatory, but partly 

 correspond. In other words, in certain cutaneous regions the 

 infrequency of points is compensated up to a certain point by the 

 lower effective liminal stimulus, or conversely, the higher liminal 

 excitation is partly compensated by a comparatively greater 

 abundance of touch spots ; in other regions, on the contrary, both 

 the mean liminal value and the number of tactile organs con- 

 tribute in raising or lowering the local sensibility to contact or 

 pressure. 



If the results which Kiesow obtained for the number of touch 

 spots in the surface unit are compared with those previously 

 worked out by Goldscheider and Blix, it is found that they are, on 

 an average, intermediate between those of Goldscheider, which are 

 excessive, and of Blix, which are too low. This depends partly on 

 the difference in the methods adopted by the three workers. 

 Alrutz (1905) controlled Kiesow's results, replacing v. Frey's 

 excitatory hair by a glass thread, which he preferred because it is 

 not affected by damp; also a hair is never straight and its 

 elasticity alters with use. His results are in entire agreement 

 with Kiesow. 



It is an interesting fact that Kiesow's results on the topo- 

 graphical variations in sensibility to pressure agree surprisingly 

 with those obtained by Weber's classical investigations with the 

 compass, which we shall presently discuss. 



Weber's observation showed that cold objects, such as coins, 

 placed on the skin are estimated to be heavier than warm 

 objects of the same weight and size. Kiesow showed that this 

 depends on the fact that cold produces a positive change of pressure 

 in the skin, in a manner analogous to a compressing mechanical 

 stimulus : heat, on the contrary, like traction, causes a negative 

 change in the pressure (Fig. 21). So that there is in the first case 



