On the Relations between Mind and Muscle, 1 7 1 



scioiisness of it, yet the removal of that pressure, as in the case of falling, 

 may produce a sensation, on the same principle as that which often causes 

 us to feel the absence, but not the presence of a stimulus. This expres- 

 sion, hotvever, is not very logical ; it only means that the nerves of a part 

 having been long accustomed to the presence of a certain object, cease to 

 communicate any impression in connection with that object, but that the 

 removal of the object occasions a new condition of the nerves which is 

 instantly recognized. This fact has been experienced by every one on 

 leaving off a ring, or any article of dress that made some degree of pres- 

 sure ; the loss of it is immediately discovered, though its presence had been 

 forgotten. Is it a similar feeling which constitutes the sensation of falling, 

 that is, loss of support ? We can scarcely account for it in this manner, 

 because the feeling is not referred to the part which had previously been 

 suffering the weight j on the contrary, it is diffused and only like itself. 

 The question then recurs, how is the feeling caused ? We cannot doubt 

 that although it cannot be identified with the sensation of pressure just 

 alluded to, it bears a very intimate relation with the state of the nerves in 

 the parts which sustained the pressure. AVhen the body is supported, there 

 must be compression in some part or other, greater or less according to 

 the extent of the supporting surface j when not supported (as when we 

 lose the centre of gravity) there is no such compression. Now although 

 neither the existence nor the absence of this comj)ression may be attended 

 with any local sensation, it is easy to conceive that those parts of the 

 brain,* which are the seats of the feeling and determine the motions of 

 equilibration, may entertain such a relation with the distant nervous ex- 

 tremities, as immediately to undergo a change when the compression of 

 the remote organ is removed, and in that change to produce the feeling 

 which we designate loss of balance, and to excite the corresponding actions. 

 Derangement of the feeling of equilibrium may have causes either exter- 

 nal or internal. To exemplify the former : — a person standing on a high 

 ladder, or on a plank stretched over a chasm, may easily lose his feeling of 

 equiHbriuro, notwithstanding the same degree of pressure is made, as is 

 usual in the upright posture. He is disturbed by his vision, which can 

 perceive no support but the surrounding airj he imagines that he is 

 falling, and instinctively throws himself into an attitude which was 

 intended to preserve the centre of gravity, but which in reality overthrows 

 it, and thus he falls in reality. Internal causes are more common; — e. g. 

 some disturbance of the nervous system produces in the individual a 

 false kind of vision j objects appear to move, and the ground on which 

 he stands, seems to rise or to fall from under him. He in this case, as in 

 the former, assumes an attitude adapted to his false conception of his rela- 

 tion to the ground on which he stands, and suffers a similar consequence. 



* The existence of such parts has been proved by modern vivisectors of animals. 



