THE NERVOUS SYSTEM. 169 



of the limbs and body, called convulsions, are the result. 

 The convulsions of young children, and the nervous agita- 

 tion of chorea, or St. Vitus's dance, are reilex in character; 

 ag are also the symptoms attending poisoning by strychnine, 

 and those terrible diseases, tetanus, or " locked jaw," and 

 hydrophobia. The severity of the convulsions is not the 

 same in all cases of these disorders ; but. in those last men- 

 tioned the most violent spasmodic movements are provoked 

 by the slightest form of irritation such as the sound of 

 pouring water, the sight of any glittering object, the glanc- 

 ing of a mirror, the contact of cool air, or even the touch 

 of the bedclothes. 



44. Another variety of reflex motions takes place in cer- 

 tain involuntary muscles, and over these the cord exercises 

 supreme control. They are principally those movements 

 which aid the performance of digestion and nutrition, the 

 valve-action of the pylorus, and other movements of the 

 stomach and intestines. In these movements the mind 

 shares no part. And it is well that this is so ; for since 

 the mind is largely occupied with affairs external to the 

 body, it acts irregularly, becomes fatigued, and needs fre- 

 quent rest. The spinal cord, on the contrary, is well fitted 

 for the form of work on which depends the growth and 

 support of the body, as it acts uniformly, and with a ma- 

 chine-like regularity. 



45. These operations are not accompanied by conscious- 

 ness ; for, als a general rule, the attention is only called to 

 them when they become disordered. Many a person does 

 not know where his stomach is situated, until he discovers 

 its position by reason of a feeling of distress within it, 

 produced by giving that organ improper work to perform. 

 In this manner the higher and nobler faculties of the 

 mind are liberated from the simply routine duties of the 



44. Another variety of reflex motions ? What are they ? What is stated of the 

 mind in connection with these movements ? 



45. Consciousness in these operations? Physical wants ? 



8 



