TOUCH. 



1177 



notions so immediately springing from sensa- 

 tions as to be often confounded with them, but 

 also for the reception of the sensory impres- 

 sions themselves. Until, in fact, the mind 

 has been affected by these impressions, no 

 sensation can be said to exist ; and that of 

 which the mind takes cognisance is not the 

 external object but the impression produced 

 by it, and not the direct or immediate impres- 

 sion produced by it upon the organ which 

 first receives it, but the change in the senso- 

 rium consequent upon this. (See SENSA- 

 TION.) That this is the true account of the 

 process is now universally admitted both by 

 the psychologist and the physiologist ; and it 

 is placed beyond all reasonable question by 

 the occurrence of those subjective sensations, 

 which, until their indications are corrected 

 by experience, may suggest the idea of an 

 external source, with such vividness and de- 

 finiteness, that the objective unreality can 

 scarcely be credited. In some instances the 

 excitement of these subjective sensations ap- 

 pears due to the occurrence of a change in 

 the part in which they are felt, which simu- 

 lates that which would be produced by an 

 external impression ; as in the case of the sen- 

 sation of extreme heat, which is often expe- 

 rienced in inflammation to a degree far beyond 

 that which the actual exaltation of tempera- 

 ture would account for ; and the pain, of va- 

 rious kinds, often resembling that inflicted by 

 external injuries, which is the result of morbid 

 changes in the part to which it is referred. 

 But in other cases they are clearly referable to 

 changes taking place in the course of the 

 nerve-trunk to the sensorium, which simulate 

 those which would naturally occur in it when 

 it is the conductor of an external impression ; 

 of this several examples have already been 

 given. Or, again, they may be due to a change 

 purely sensorial ; as in the various cases of 

 " radiation of sensations " elsewhere alluded 

 to (see SENSATION); or, as in the sensations 

 of nausea, of shuddering, of tickling, of pain, 

 &c., which are frequently excited by changes 

 purely mental. The degree of intensity, 

 again, with which actual sensations are felt, 

 depends as much upon the state of the mind 

 as upon that of the corporeal organism. 

 Thus, if we experience a slight itching in the 

 skin, and direct our thoughts to it, we are 

 speedily annoyed by its increase ; whilst, if 

 we steadily fix our thoughts upon some 

 other object, we are soon unconscious of the 

 irritation. On the other hand, the complete 

 absorption of the mind in some train of 

 thought which engrosses its attention, may 

 render the individual unconscious of impres- 

 sions that would ordinarily induce severe 

 pain. This is remarkably seen in cases of 

 natural and artificial somnambulism (see 

 SLEEP) ; and it is probable that in many of 

 the cases in which insane patients have in- 

 flicted severe wounds upon themselves, with- 

 out appearing to feel pain, the cause of the 

 immunity from suffering is to be found in the 

 entire possession which some dominant feel- 

 ing or idea has of their consciousness, so that 



they are not cognizant of any external im- 

 pressions but such as harmonize with it. 

 Even in ordinary cases, it is well known that 

 a severe injury suddenly inflicted, is much 

 less felt at the moment than a far slighter 

 injury of which the mind has been in expec- 

 tation ; thus, a limb has been carried away by 

 a cannon-ball, or the chest traversed by a 

 bullet, with far less consciousness of pain than 

 is produced by the trivial incision made in 

 ordinary venesection. 



Improvcabiiiti/ of the Sense of Touch. The 

 mental participation in the phenomena of 

 tactile sensation is further rendered obvious 

 by the improvement in discriminating power 

 which results from continual attention to its 

 indications. Of this we have examples in the 

 case of certain artisans, whose employments re- 

 quire them to cultivate their tactile discrimina- 

 tion ; thus, the female silk-throwsters of Bengal 

 are said to be able to distinguish by the touch 

 alone twenty different degrees of fineness in 

 the unwound cocoons, which are sorted ac- 

 cordingly ; and the Indian muslin-weaver con- 

 trives, by the delicacy of his touch, to make 

 the finest cambric in a loom of such simple 

 construction, that European fingers could at 

 best propose to make a piece of canvas in it. 

 The improvement in tactile discrimination is 

 more especially seen, however, in those indi- 

 viduals whose dependence upon it is increased 

 by the loss or deficiency of other senses ; and 

 especially by blindness, congenital or ac- 

 quired. Whilst it is doubtless to be attri- 

 buted, in great part, to the concentration of 

 the attention and of the powers of recollec- 

 tion and comparison upon the sensations 

 which are brought (as it were) to the mind, 

 it may not seem altogether improbable that 

 the improvement may in part depend upon an 

 increased development of the tactile organs 

 themselves ; resulting from that augmented 

 nutrition which would be the natural con- 

 sequence of the frequent use of them, and of 

 the increased flow of blood that seems to take 

 place towards any part on which the attention 

 is continually fixed. Certain it is, that many 

 blind persons can not merely obtain as defi- 

 nite and accurate conceptions of the form, 

 surface, &c., of objects over which they ra- 

 pidly pass their hands, as others could only 

 derive from the long and painstaking examin- 

 ation of them by their tactile organs ; but the}' 

 can discriminate minute differences, of which 

 those who have not specially cultivated this 

 faculty remain quite unconscious, even when 

 their attention is pointedly directed to their 

 discovery. The process by which the blind 

 learn to read from books printed in an ele- 

 vated type for their special use, affords an 

 interesting illustration of the nature of the 

 improveability of the proper sense of touch. 

 On first making the attempt, the learner needs 

 to use a large type; and even although (to a 

 person who has previously enjoyed his sight), 

 the visual form of each letter may be well 

 known, yet considerable experience is required 

 for the ready recognition of the tactile form of 

 each separate letter. After this step has been 



