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Show 342 tn,tJSHtNG. CHAP. X!ll. When we direct our whole attention to any one sense its acuteness is increased; 40 and the continued habit' of close attention, as with blind people to that of hearing, and with the blind and _deaf to. that of touch, appears to improve the sense Jn question yermanently. There is, also, so1ne reason to beheve, judging from the ·capacities of differen~ races of ~an, that the effects are inherited. Turning to ordinary sensations it is well known that pain is increased by attending to it; and Sir B. ~roclie goes so far as to believe that pain may be felt In any part of the body to which attention is closely drawn.41 Sir H. Holland also remarks that we become not only conscious of the existence of a part subjected to concentrate~ attention, but we experience in it various odd sensations, as of weicrht, heat, cold, tingling, or itching.42 Lastly, some physiologists maintain that the mind can influence the nutrition of parts. Sir J. Paget has given a curious jnstance of the power, not indeed of the mind ' but of the nervous system, on th.e hair. A lady "who is subject to attacks of what IS " called nervous headache, always finds in the morning " after such an one, that some patches of her hair " are white, as if powdered with starch. The change . " is effected in a night, and in a few days after, the 0 h 0 d k b 0 h 1 "43 " hairs gradually regain t eir ar rownis co our. <1o Dr.l\1audsley has given(' rrhe Physiology and Pathology of 1\Iin.d,' 2nc1 edit. 1868, p.105), on good authority, some curious statements ~~1 th respect to tho improvement of the sense of touch by practice and a cni tion. It is remarkable that when this sense has thus been r~nclor.ec more aeute at any point of the body, for instance, in a finger, it is hkeWIRe improved at the conesponding point on the opposite siclo of the boclY·1, 41 ' The Lancet,' 1838, pp. 30-40, as quoted by Prof. Laycoc \' 'Nervous Diseases of Women,' 1840, p. 110. 42 'Chapters on Mental Physiology,' 1858, PP· !H-93. f 43 Lectures on Surgical Pathology,' 3nl edit. revised by Pro· Tu1·ner, 1870, pp. 28, 31. CHAP. XIII. BLUSHING. 343 ~Ve thus see that close attention certainly affects various parts and organs, which are not properly under the control of the will. By what means attentionperhaps th~ mos~ wonderful of all the wondrous powers of :he m1nd-1~ effected, is an extremely obscure subJect. Accordmg to Miiller,14 the process by which the sensory cells of the brain are rendered throuah t~e w~U, susceptible of receiving more intens~ and distinct Impressions, is closely analogous to that by which the motor cells are excited to send nerve-force to the ;oluntary _muscles. There are many points of analogy ~n the action of the sensory and motor nerve-cells · for 1nstance, the familiar fact that close attention to' any one sense causes fatigue, like the prolonged exertion of any one muscle.~5 \Vhen therefore we voluntarily concen~rate our _atton~ion on any part of the body, the c~lls of the brain which receive impressions or sensations from that part are, it is probable, in some unknown ma.nner stimulated into activity. This may account, \~Ith~ut any local change in the part to which ou~ attent~on IS earnestly directed, for pain or odd sensations being there felt or increased. If, however, the part is furnished with muscles we cannot feel sure, as 1\Ir. Michael Foster has rema~ked to. me, that some slight impulse may not be unconBcwusly sent to such muscles; and this would probably cause an obscure sensation in the part. In a large number of cases, as with the salivary and ln.cryrr:al,. glands, intestinal canal, &c., the power of a:ten;~on se~ms to rest~ either chiefly, or as some phyI~ lobists tlunk~ exclusively, on the vaso-motor system being affected In such a manner that more blood is :: ' Elements of Physiolo?'y,' Eng. translat. vol. ii. p. 938. Prof. Laycock has discussed this point in a very l. t . t ' manner· S ee 1u ·s 'N.r c rvous n·1 sca, cs of "\Vomen,' 18-10, p. llOn. cJcs lill•Y |
