them, the person experimented upon will feel as if they began to diverge near the mouth and to include it in a well-marked ellipse. In like manner, if we keep the compass-points one or two centimetres apart, and draw them down the fore-arm over the wrist and palm, finally drawing one along one finger, the other along its neighbour, the appearance will be that of a single line, soon breaking into two, which become more widely separated about the wrist, to contract again in the palm, and finally diverge rapidly again towards the finger-tips.
The same length of skin moreover will convey a more extensive sensation according to the manner of stimulation. If the edge of a card be pressed against the skin, the distance between its extremities will seem shorter than that between two compass-tips touching the same terminal points.
The skin seems to obey a different law from the eye here. If a given retinal tract be excited, first by a series of points, and next by the two extreme, points, with the interval between them unexcited, this interval will seem considerably less in the second case than it seemed in the first. In the skin the unexcited interval feels the larger. The reader may easily verify the facts in this case by taking a visiting card, cutting one edge of it into a saw tooth pattern, and from the opposite edge cutting out all but the two corners, and then comparing the feelings aroused by the two edges when held against the skin.
In the eye, intensity of nerve-stimulation seems to increase the volume of the feeling as well as its brilliancy. If we raise and lower the gas alternately, the whole room and all the objects in it seem alternately to enlarge and contract. If we cover half a page of small print with a grey glass, the print seen through the glass appears decidedly smaller than that seen outside of it, and the darker the glass the greater the difference. When a circumscribed opacity in front of the retina keeps off part of the light from the portion which it covers, objects projected on that portion may seem but half as large as when their image falls outside of it.[1] The inverse effect seems produced by certain drugs and anaesthetics. Morphine, atropine, daturine and cold blunt the sensibility of the skin, so that distances upon it seem less. Haschish produces strange perversions of the general sensibility. Under its influence one's body may seem either enormously enlarged or strangely contracted. Sometimes a single mem-
- ↑ Classen, Physiologie des Gesichtssinnes, p. 114; see also Riehl, Der Philosophische Kriticismus, ii., p. 149.
