MOVEMENTS.

2. I shall commence the detailed exposition of the Law of Contiguity with the case of Muscular Activity, including under this head all kinds of movements, attitudes, and efforts of resistance.

Through the intellectual property of adhesiveness or plasticity, as expressed by this principle of contiguous association, movements can be linked together in trains and made to succeed each other, with the same certainty and invariable sequence as we find in the instinctive successions of rhythmical action already discussed. The complicated evolutions of a dance come to flow of their own accord, no less than the movements on all fours of the newly dropped lamb.

We may begin with remarking the operation of the adhesive principle upon the spontaneous and instinctive actions themselves. These actions are plainly confirmed and invigorated by repetition. Although many creatures can walk as soon as they are born, they walk much better after a little practice. Here, however, we cannot easily make allowance for the growth of the parts themselves, apart from the effect of exercise. The muscles of the limbs increase in size, and the nerve-centres that stimulate and organize the rhythmical movements acquire more development through time alone. We are, therefore, not in a good position, in the case of the instincts, to trace and estimate the force of adhesive growth due to this principle of contiguity. But knowing, as we do, how the force operates in all the voluntary operations, we are entitled to presume that it works also in the various instinctive operations. By practice, that is, by repetition, the infant sucks with more ease and vigour. In learning to walk, exercise undoubtedly concurs with the primitive alternating tendency of the limbs. The muscles of the body are strengthened by the mere action of growth; this growth is accelerated if they are regularly exercised within limits; and the very same is likely to be true of the nerves and nerve-centres that dictate the flow and alternation of muscular movements.

I have endeavoured to establish as a fact the spontaneous commencement of all the actions that we term voluntary. Thus the limbs, the features, the eyes, the voice, the tongue, the jaw, the head, the trunk, &c., commence to move in consequence of an unprompted flow of stimulus from the nervecentres; this flow will be sometimes to one set of members and sometimes to another, so that the organs may act sepa rately and independently, under the influence thus imparted. Now such spontaneous movements are without doubt confirmed by repetition, and are thereby made to recur more readily in the future. Any movement struck out by central energy leaves as it were a track behind, and a less amount of nervous impulse will be required to set it on a second time. By a spontaneous stimulus the hands are closed; the act of closing determines a current or bent in that direction, and the next exertion is so much the easier. By one prompting the arms are raised and lowered alternately; by another they are moved forwards and backwards; in the course of a few repetitions adhesiveness comes in aid of the inward stimulus, and the movements grow more frequent and more decided. Through the spontaneous action of the centres the eyes are moved to and fro, and iteration gives facility to the exercise. So the voice is moved variously by an impulse from within, and each movement and note is made easier for the next occasion when the centres discharge their energy by that channel. The tongue is an organ with many movements, and all voluntary; these commence of their own accord, and are strengthened and as it were developed by repetition. The inclinations and sweep of the head, and of the trunk generally, are of the same class. The iteration of all these various movements does not make them voluntary movements in the proper sense of the expression; but it prepares them for becoming such by a future and distinct acquisition. It makes them recur more frequently and more readily, enhancing the spontaneous impulse of the centres. At one time the voice sounds

a high note. As to the first stimulus of this effort, we can say nothing farther than that with all the active organs there is associated a nervous battery for commencing their move

ACQUISITION OF COMPLEX MOVEMENTS.

321

ments. After an interval, the same high note is hit upon by a like discharge from the proper centre. When several repetitions have occurred in this way a facility is gained; either a less tension of the centre will originate the note, or it will be better sustained when it comes. On a different occasion a stream of sound is stimulated at a low pitch, which after a number of opportunities comes to be a ready effort of the organ. Thus it is that a variety of detached movements are getting themselves prepared for subsequent use.

To persons that have not reflected on the very great difficulty and labour attending the growth of voluntary movements in infancy, this hypothesis of spontaneity so much dwelt upon will seem uncalled for and unlikely. But I shall have to show at a later stage how impossible it is to account for the origin of volitional acts without a supposition of this nature.

The movements inspired by Emotion are also cultivated and confirmed by repetition; and a certain increase of power is gained in this way. The voice is developed by crying, the trunk and limbs and features by gesticulation. There is no proof that the emotional stimulus of the movements contributes in any degree to give the voluntary command of them; there seems to be a great gulf permanently fixed between these two sources of active display. Emotion cultivates itself solely. The vigour of gesticulation may be increased, but not the vigour of setting on movements independently of the excitement of the feelings.

3. We pass next to the acquisition of trains and aggregates of movements in the ordinary course of education in mechanical art and handicraft. I assume the case of an individual already able to command the limbs, or other parts, as directed by another person, or by an example set for imitation; and postpone the consideration of the mode in which this voluntary power is itself acquired, as demanding a far more subtle line of investigation.

The simplest acquisition is the case where something is added to a movement already established. Take the case of walking, and suppose that we desire to communicate a peculiar

Y

set of the limb, for example the turning out of the toes. A voluntary act, directed to the muscle that rotates the thigh outward, gives the requisite position to the foot; and the act is sustained while the walking movement goes on. By this means there grows up in course of time an adhesion between the tension of the rotator muscles and the several movements of walking, and at last they coalesce in one complex whole, as if they had been united in the original mechanism of the system. This agglutination of acts is very common among our mechanical acquirements. Thus in learning to walk, a vast deal of adjustment is necessary before we can maintain our balance. We require, along with the movements of the limbs, to execute coinciding movements of the head, arms, and trunk, in order that the body may never depart from a balanced posture. These remoter movements become so fused with the main action as to be inseparable from it. The same stream of nervous action that keeps up the alternation of the limbs, directs a measured current towards specific muscles of the body and upper extremities, and the entire complication seems as if it were but a single member.

In the foregoing examples we have included two different cases, both coming under the head of agglutination, or coinciding actions: the one is where a fixed tension is maintained in the accessory action, as in walking with the foot turned outwards, the other supposes two trains of movements fused together. There is abundance of instances of both kinds, and the principle of operation is identical in the two. I shall now take an illustration of a succession of actions formed exclusively by the adhesive principle. The sequence of acts in eating is an example taken from our earliest acquirements. The lifting of the morsel by the spoon or fork, the carrying it to the mouth, the opening of the mouth at the right moment, the action of the jaws and tongue, all exhibit a succession of regulated acts fixed into mechanical coherence and certainty by the mere fact that they have been made to succeed each other a great number of times. The action of carrying the hand to the mouth is followed by the opening of the jaws,

PURE MUSCULAR ADHESION.

323

as surely as the two alternate acts concerned in breathing give birth to each other.

In a great number of mechanical successions, the feeling of the effect produced at each stage is an essential link in the transition to the next. Thus in writing, the sight of the part last formed is the preamble to what comes next, as much so as the motion executed; in which case the sequence is not one of pure motions-one motion bringing on the next in the habitual order. But the mixture of sensations and motions in complex trains will form a separate head; I am desirous, at this stage, to confine the illustration to examples of movements linked together, without any other element being present. As, however, the guidance of the feeling is necessary in the course of learning any mechanical effort, the fixing of movements in a train independently of such guidance is the last stage, or highest perfection, of mechanical acquirement. Thus, in playing on a pianoforte, and attending to something else at the same time, the sequence must be one almost entirely of movements: that is to say, each stroke is associated with another definite stroke or touch through the whole succession of the piece. But even in this case, it is difficult to say how much there is of a kind of latent sensation in the fingers and the ear, sufficient for the purposes of association, acting along with the association of pure movements.

A deaf person speaking must depend almost entirely on the associated sequence of movements; the only other assistance being the muscular feelings themselves, which always count for something. In saying over words committed by rote, the sequence of articulate motions is perfect. One word uttered brings on the next independent of either hearing or the feeling of articulation. This is a proof of the very great aptitude for associated movement belonging to the vocal organs; for hardly any other part of the body, not even the hands, can acquire such perfection of unconscious dexterity. In knitting, there is probably the same sequence of movements, acquired after thousands of repetitions. The simpler figures of dancing can be gone through with this mechanical