THE PEBCEPTION OF SPACE. (l.) 23

excited spot. How can it suggest its position ? Not by recalling any particular line unless experience have constantly been in the habit of marking or tracing some one line from it towards some one neighbouring point. Now on the back, belly, viscera, &c., no such tracing habitually occurs. The consequence is that the only suggestion is that of the whole neighbouring circle, i.e., the spot simply recalls the general region in which it happens to lie. By a process of successive construction, it is quite true that we can also get the feeling of distance between the spot and some other particular spot. Attention, by reinforcing the local-sign of one part of the circle, can awaken a new circle round this part, and so de proche en proche we may slide our feeling down from our cheek say to our foot. But when we first touched our cheek we had no consciousness of the foot at all. 1 In the extremi- ties, the lips, the tongue and other mobile parts, the case is different. We there have an instinctive tendency, when a part of lesser discriminative sensibility is touched, to move the member so that the touching object glides along it to the place where sensibility is greatest. If a body touches our hand we move the hand over it till the finger-tips are able to explore it. If the sole of our foot touches anything we bring it towards the toes, and so forth. There thus arise lines of habitual passage from all points of a member to its sensitive tip. These are the lines most readily recalled when any point is touched, and their recall is identical with the consciousness of the distance of the touched point from the 'tip'. I think anyone must be aware when he touches a point of his hand or wrist that it is the relation to the finger-tips of which he is usually most conscious. Points on the fore-arm suggest either the finger-tips or the elbow (the latter being a spot of greater sensibility). 2 In the foot it is the toes, and so on. A point can only be cognised in its relations to the entire body at once by awakening a visual 1 Unless, indeed, the foot happen to be spontaneously tingling or some- thing of the sort at the moment. The whole surface of the body is always in a state of semi-conscious irritation which needs only the emphasis of attention, or of some accidental inward irritation, to become strong at any point. 2 It is true that the inside of the fore-arm, though its discriminative sensibility is often less than that of the outside, usually rises very promi- nently into consciousness when the latter is touched. Its (esthetic sensi- bility to contact is a good deal finer. We enjoy stroking it from the extensor to the flexor surface around the ulnar side more than in the reverse direction. Pronating movements give rise to contacts in this order, and are frequently indulged in when the back of the fore-arm feels an object against it.