198 LOCOMOTION. [CHAP. VIT. 



the left leg is now brought under it, and receives its weight, by 

 which the body is in turn inclined to the left. The right leg, 

 which had been extended, is then bent, raised from the ground, and 

 swung forwards, ready again to sustain and project the body, when 

 the left leg has gone through a similar movement. In running, the 

 muscular actions are performed in a similar succession, but more 

 rapidly and more vigorously. The body is more bent forwards, and 

 its weight made more effectually to aid progression. In leaping, the 

 body is projected by a sudden extension of both the lower limbs, and 

 raised, for a brief time, entirely from the ground, the feet being 

 advanced again in time to receive its weight as it descends. 



2. As to the Manner in which Movements of the Voluntary Muscles 

 are excited. These muscles are subject, through the motor nerves, 

 to the influence of several remote stimuli, already enumerated, and 

 the chief of which, volition, gives its name to the class. These 

 stimuli, in the healthy body, impress the motor nerve in the ner- 

 vous centre, and the effect is a contraction of the muscle. By an 

 exertion of the will we can contract more or fewer muscles at once, 

 and to any degree, within certain limits : we can contract anta- 

 gonist muscles together, or alternately, and through a longer or 

 shorter period. 



But every voluntary muscle is subject to other influences more 

 certain and more powerful in their operation than the will, and to 

 which the will has often to yield. The wonderful and characteris- 

 tic movements of the body, and especially of the features under the 

 impulses of passions and emotions, are all involuntary, of which the 

 best proof is to be found in the very partial power the will has of 

 restraining them. To imitate the movements of passion is a task 

 of extreme difficulty ; and those actors succeed the best who lose 

 themselves the most in their characters, that is, who the most com- 

 pletely assume for the time the passion they design to pourtray. 

 Without this quality the most elaborate imitation is cold, and fails 

 to touch our sympathies. The genius of the histrionic artist con- 

 sists chiefly in this power. 



Many movements ensue involuntary, when certain impressions 

 are made on the surface of the body, or in any part of its interior, 

 either by external or internal causes. Such impressions are usually 

 attended with consciousness, but sometimes not ; so that there is no 

 reason to believe that perception of the impression is in any way 

 essential to the production of the movement. All such movements 

 are termed reflex. The contraction of the oesophagus in swallowin 

 is an example of them without consciousness. The sudden inspira- 



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