168 PSYCHOLOGY. 



of the minuteness with which we are able to subdivide the 

 total bigness of the sensation it yields. On its periphery 

 the local differences do not shade off very raj)idly, and we 

 can count there fewer subdivisions. 



But these local differences of feeling, so long as the surface 

 is unexcited from luithout, are almost null. I canot feel them 

 by a pure mental act of attention unless they belong to quite 

 distinct parts of the body, as the nose and the lip, the finger- 

 tijD and the ear ; their contrast needs the reinforcement of 

 outward excitement to be felt. In the spatial muchness of 

 a colic — or, to call it by the more spacious-sounding verna- 

 cular, of a ' bellyache ' — one can with difficulty distinguish 

 the north-east from the south-west corner, but can do so 

 much more easily if, by pressing one's finger against the 

 former region, one is able to make the pain there more in- 

 tense. 



The local differences require tJien an adventifioi's sensa- 

 tion, superinduced upon them, to awaken the attention. After 

 the attention has once been awakened in this way, it may 

 continue to be conscious of the unaided difference ; just as 

 a sail on the horizon may be too faint for us to notice until 

 someone's finger, placed against the spot, has pointed it out 

 to us, but may then remain visible after the finger has been 

 withdrawn. But all this is true only on condition that 

 separate points of the surface may be exclusively stimulated. 

 If the whole surface at once be excited from without, and 

 homogeneously, as, for example, by immersing the body in 

 salt water, local discrimination is not furthered. The local- 

 signs, it is true, all awaken at once ; but in such multitude 

 that no one of them, with its specific quality, stands out in 

 contrast with the rest. If, however, a single extremity be 

 immersed, the contrast between the wet and dry parts is 

 strong, and, at the surface of the water especially, the local- 

 signs attract the attention, giving the feeling of a ring sur- 

 rounding the member. Similarly, two or three wet spots 

 separated by dry spots, or two or three hard points against 

 the skin, will help to break up our consciousness of the 

 latter's bigness. In cases of this sort, where points re- 

 ceiving an identical kind of excitement are, nevertheless, 

 felt to be locally distinct, and the objective irritants are also 



