541 D. Considering in the next place the alleged sensibility of certain persons to crystals and magnets, - known to be absolutely inert in relation to ordinary men, - we should note the alleged connection between the perception of magnets and that of running water. And here we may note in passing a point which in these inquiries should be often remembered. I mean the great irregularity with which sensibilities are distributed in the organic world; - even sensibility to a stimulus so potent and universal as light itself. The mere fact that sensibility to magnets has not yet been observed is no strong presumption against its being observed before long. The central organs of perception, as yet unexhausted in their manifestation by the external organs, may, for aught we can say, possess this potential sensibility, to be developed in process of time.

Some experiments intended to test the reality of the "magnetic sense," and especially of the so-called "magnetic light" - luminous appearances described by Baron Reichenbach as being seen by his sensitives in the neighbourhood of magnets - were carried out by a Committee of the S.P.R. in 1883. After careful and repeated trials with forty-five "subjects" of both sexes and of ages between sixteen and sixty, only three of these professed to see luminous appearances. They were entirely ignorant of Reichenbach's works, and no information was given to them beforehand of the nature of the experiment. The sensations they described were remarkably concordant. The light, they said, took the form of two rounded or blunted cones, apices downwards, one of each being directly over and upon a pole of the magnet. The chief instrument used was an electro-magnet, and the light appeared and disappeared with the making and breaking of the current, unknown to the subject. Two of the subjects and a member of the Committee also experienced peculiar sensations in the face and head when the head was placed in the strongest part of the magnetic field, by which they were able to distinguish accurately whether the magnet was excited or not.

The value of these experiments as evidence of a magnetic sense of course depends primarily on whether the subjects had any means, direct or indirect, of knowing when the current was made or broken. The precautions taken to avoid this and the other conditions of the experiments are described in detail in the report of them in the Proceedings S.P.R., vol. i. pp. 230-237. See also a further note by the Chairman of the Committee, Professor W. F. Barrett, vol. ii. pp. 56-60.

541 E. And next as to the heteræsthesiae alleged to be evoked by dead organic substances, or by living organisms. We may begin by observing that some of our senses, at any rate, form the subjective expression of certain chemical reactions. But many kinds of chemical reactions go on in us besides those which, for example, form the basis of our sense of taste. And some persons are much more affected than others by certain special reactions, which from a purely chemical point of view may or may not be precisely the same for all. Some persons have a specific sensibility to certain foods, or to certain drugs; - the presence of which their stomach detects, and to which it responds with extraordinary delicacy. Now, if it were an important object to discover the presence of a certain drug, such a sensibility would be regarded as a precious gift, and the discovery might be quite as valuable when made by the stomach as it would have been if made by the nose. These are nascent heteræsthesiae, which, however, are not fostered either by natural selection or by human care.

Of similar type are the specific sensibilities to the presence of certain plants or animals, - familiar in certain cases of "rose-asthma," "horse-asthma," and discomfort felt if a cat is in the room. These feelings have many causes. At one end there is ordinary mechanical irritation by solid particles. At the other end of the scale there is, of course, mere self-suggestion. But between the two there seems to be a kind of sensibility which is not purely self-suggestive, and not exactly olfactory, but resembles rather the instincts by which insects or other animals discern each other's neighbourhood.

There seems indeed no reason why the sense still vaguely known as smell should not be divisible into as many specific sensibilities as the sense which till lately was vaguely known as touch. On the one hand, sensibility to effluvia - even assuming all smell to depend on effluvia - is not confined to the nose, and may surely take varied forms as various tracts of mucous membrane are affected. And, on the other hand, the animal kingdom shows us in abundant instances a sense of smell already developed to a point which surpasses the sense of hearing and rivals the sense of sight.

Now, the very fact that the bloodhound can distinguish as he can a given person's traces from all the world beside is enough, I think, to point to the probability that the hypnotised subject, - already hyperæsthetic and perhaps heteræsthetic, - may distinguish between one human being and another in a manner, and with an acuteness, to us unknown. A natural direction for heteræsthesiae to take would seem to be a revival of primitive powers, till now developed more fully in other animal races than in man.

Returning, then, from this new point of view to the problem of the influence of mesmeric passes, we see that there are now two different lines of observation which point to the probability of their possessing some specific potency. From the supernormal or spiritual side I urge that since telepathy from a distance is a vera causa of hypnosis (see 568), mesmeric passes near at hand may possess some similar - hypnogenous value. And from the normal or material side I urge that among the delicate discriminative powers with which hypnotism is found to endow the sensitive subject, it is not unlikely that we shall find some specific sensibility to human proximity per se, and perhaps to the proximity of certain human beings, as distinguished from the rest.

It is perhaps through some such power of discrimination that effects are produced on sensitive subjects by "mesmerised objects," - assuming, of course, that sufficient care has been taken to avoid their discovering by ordinary means that the objects have been specially manipulated in any way. See some experiments recorded in the Proceedings S.P.R., vol. i. pp. 260-262, and a description of Esdaile's experiments with mesmerised water in vol. iii. p. 409; also cases in the Zoist, e.g. vol. v. p. 129, and vol. x. p. 99.