60 PHYSICAL EXPRESSION. 



spontaneous movement is equally indicative of good 

 nutrition in animals. Note the frisky play of 

 puppies and kittens. The sickly dog, whose nutri- 

 tion is greatly impaired, can hardly lift a paw or wag 

 his tail. In some pathological conditions movement 

 may be in excess, and not indicative of a good con- 

 dition of nutrition ; but it will not be convenient to 

 enter upon the discussion of this matter at present.* 

 In speaking of the modes of expression by move- 

 ment, we can hardly be permitted to pass silently 

 over the consideration of the difference between 

 spontaneous and voluntary movements, but it must 

 be remembered that we are not here directly con- 

 cerned with the essential properties expressed by 

 the objective signs. My reason for passing over so 

 important a point is that a discussion as to the 

 criteria distinguishing spontaneous from voluntary 

 movements would involve us in a philosophical 

 argument out of place in this work. Having care- 

 fully considered this point, I have come to the con- 

 clusion that, in place of attempting to distinguish 

 between spontaneous and voluntary movements, it 

 will be easier and more satisfactory to study inborn, 

 and acquired sources of movement. Movements 

 seen to occur upon birth and soon after, may be 

 assumed to depend upon inborn conditions, causes 

 inherent in the subject at birth, so that such move- 

 ments may be called inborn movements. As 

 previously said, the child upon birth presents very 

 constant movements, which may be conveniently 

 spoken of as inborn in contradistinction to the 

 * See chap. vii. p. 125. 



