20 ELEMENTARY PHYSIOLOGY less. 



must contract, or the legs and body would fall forward. 

 But this action tends to bend the leg ; and to neutralise 

 this and keep the leg straight, the great muscles in front 

 of the thigh (Fig. 6, 2) must come into play. But these, 

 by the same action, tend to bend the body forward on the 

 legs ; and if the body is to be kept straight, they must be 

 neutralised by the action of the muscles of the buttocks 

 and of the back (Fig. 6, III). 



The erect position, then, which we assume so easily and 

 without thinking about it, is the result of the combined 

 and accurately proi)ortioned action of a vast number of 

 muscles. What is it that makes tliem work together in 

 this way ? 



Let any person in the erect position receive a violent 

 blow on the head, and you know what occurs. On the 

 instant he drops prostrate, in a heap, with his limbs re- 

 laxed and powerless. What has ha[)pened to him ? The 

 blow may have been so inflicted as not to touch a single 

 muscle of the body ; it may not cause the loss of a drop 

 of blood ; and, indeed, if the "concussion," as it is called, 

 has not been too severe, the sufferer, after a few moments 

 of unconsciousness, will come to himself, and be as well 

 as ever again. Clearly, therefore, no permanent injury 

 has been done to any part of the body, least (jf all to the 

 muscles, but an influence has been exerted upon a some- 

 thing which governs the muscles. And a similar influence 

 may be the effect of very subtle causes. A strong mental 

 emotion, and even a very bad smell, will, in some people, 

 produce the same eff"ect as a blow. 



These obser\ations might lead to the conclusion that it 

 is the mind which directly governs the muscles, but a 

 little further in(iuiry will show that such is not the case. 

 For people have been so stabbed, or shot in the back, as 

 to cut the sjiinal cord, without any considerable injury 

 to other jjarts : and then they have lost the power of stand- 

 ing upright as much as before, thougli their minds may 

 have remained perfectly clear. And not only have they 



