834 OF THE STRUCTURE AND FUNCTIONS OF MUSCULAR TISSUE. 



consciously to ourselves, in the act of walking. The difficulty which would 

 attend the voluntary harmonization of all these separate actions, is remark- 

 ably evinced by the fact, that no mechanist, however ingenious, has ever 

 succeeded in constructing an automaton that should walk like Man ; the 

 alternate shifting of the centre of gravity from one side to the other, upon 

 so small a base as the human foot affords, simultaneously with the move- 

 ment in advance, constituting the great difficulty of biped progression. But 

 all this adjustment is effected in our own organism for us, rather than by us; 

 the act of harmonization, when once fully mastered, being attended with no 

 effort to ourselves; but the whole series of complex movements being per- 

 formed in obedience to the simple determination to walk, under the auto- 

 matic guidance of the senses, which instantly reveal to us any imperfection 

 in the performance. The same view extends itself readily to other combi- 

 nations of dissimilar and non-symmetrical movements, which are less natural 

 to Man, but which may be readily acquired artificially if they all harmonize 

 in a common purpose, and are under the guidance of the same set of sensa- 

 tions. Thus, the performer on the Organ uses the several fingers of his two 

 hands to execute as many different movements (in very different positions, 

 it may be) on the " manual " keys : one of his feet may be on the " swell " 

 pedal, and the other may be engaged in playing on the "pedal " keys ; but 

 all these diverse actions are harmonized by their relation to the same set of 

 auditory sensations ; and if the result be not that which the performer an- 

 ticipated, an immediate correction is made. The preferential use of the 

 right arm and leg is not easily explicable. Dr. Pye Smith 1 refers it to the 

 principle of the "survival of the fittest." contending that in warfare those 

 who advance the right side would in the long run be exposed to less risk of 

 fatal wounds. Dr. Ogle, 2 however, points out that the right extremities are 

 used preferentially by other animals, as the monkey and parrot, and refers 

 it to the fact that the left hemisphere receives a freer supply of blood than 

 the right. It may to some extent proceed from imitation, and to some ex- 

 tent also be the result of education. 



683. It would be easy to multiply instances of the same kind, all illus- 

 trative of the general principle, that the facility with which wo voluntarily 

 combine different movements is chiefly determined, not by their symmetrical 

 character, but by their conformableness to a common end, and by the harmony 

 of their guiding sensations with reference to that end; 3 but it will be desir- 

 able to dwell particularly on the Movements of the Eye, as presenting certain 

 points of peculiar interest, some of which have an important bearing on 

 Surgical practice. It will be recollected that in the Human Orbit, six mus- 

 cles for the movements of the eyeball are found; the four Recti, and the 



1 Guy's Hosp. Rep., 1871. 



2 Rep. of Med.-Chir. Sue., Lancet, 1871,p. 449. Sec also, for scattered Notes and 

 Observations on this subject, Lancet, 1870, vol. i, pp. W(i, 5~>7, WiO; 1871, vol i, p. 

 495; vol. ii, pp. 49 and 111 ; Buchanun, Theory of the Right Hand, Edinburgh Med. 

 Journ., 1863, and Pamphlet, Glasgow, ISii'J. 



1 Two simple examples, however, may ! cited, of the difficulty which attends the 

 simultaneous performance of movements that are not harmonious. If we attempt to 

 elevate one eyelid whilst we are depressing the other, we find that a considerable 

 effort is rei|iiire<l to accomplish the action, although the elevation or depressing of 

 both rylids together is performed with so little effort that we are scarcely conscious 

 of it; and the difficulty is increased if we half shut both eyes, and then try to close 

 one and to open the other. So if we try to move our two hands as if they were xinml- 

 (ntn'oiifili/ winding cord in opposite direction* upon two reels placed in front of us, we 

 shall find ourselves unable to do so without n constant exercise of the attention, and 

 even then bnt slowly and with difficulty ; although the very same movements may be 

 separately performed, or both hands may be made thus to move in the same direction, 

 with the greatest facility. 



