=The Localizing Power of the Skin.=--"When the eyes are closed and a point of the skin is touched we can with some accuracy indicate the region stimulated; although tactile feelings are in general characters alike, they differ in something besides intensity by which we can distinguish them; some sub-sensation quality not rising definitely into prominence in consciousness must be present, comparable to the upper partials determining the timbre of a tone. The accuracy of the localizing power varies widely in different skin regions and is measured by observing the least distance which must separate two objects (as the blunted points of a pair of compasses) in order that they may be felt as two. The following table illustrates some of the differences observed: Tongue-tip 1.1 mm. (.04 inch) Palm side of last phalanx of finger 2.2 mm. (.08 inch) Red part of lips 4.4 mm. (.16 inch) Tip of nose 6.6 mm. (.24 inch) Back of second phalanx of finger 11.0 mm. (.44 inch) Heel 22.0 mm. (.88 inch) Back of hand 30.8 mm. (1.23 inches) Forearm 39.6 mm. (1.58 inches) Sternum 44.0 mm. (1.76 inches) Back of neck 52.8 mm. (2.11 inches) Middle of back 66.0 mm. (2.64 inches) The localizing power is a little more acute across the long axis of a limb than in it; and is better when the pressure is only strong enough to just cause a distinct tactile sensation than when it is more powerful; it is also very readily and rapidly improvable by practice." It seems to be naturally delicate in proportion as the skin which possesses it covers a more movable part of the body. [Illustration: FIG. 25.]