THE NERVOUS SYSTEM 229 



43. An excess of this activity may also be observed in 

 disease. In this condition, the excitability of the cord is 

 unnaturally aroused, and frequent and violent movements of 

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

 convulsions of young children, and the nervous agitation of 

 chorea, or St. Vitus's dance, are reflex in character, as 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 mentioned, 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 glancing of a mirror, the contact 

 of cool air, or even the touch of the bed-clothes. 



44. Another variety of reflex motions takes place in certain 

 involuntary muscles, and over these the cord exercises supreme 

 control. They a_re principally those movements which aid the 

 performance of digestion and nutrition, the valve-action of the 

 pylorus, and ether movements of the stomach and intestines. 



cious meal, a single sleepless night, a single passion or piece of bad news, 

 will destroy it. On the other hand, a vivid hope, a cheerful resolve, an 

 absorbing interest will restore it as if by magic. For in man, these lower 

 officers in the nervous hierarchy draw their very breath according to the 

 bidding of the higher powers. But the dependence of the higher on the 

 lower is no less direct. The mutual action takes place .in each line. A 

 chief condition of keeping the brain healthy is to keep these unconscious 

 nervous functions in full vigor, and in natural alterations of activity and 

 repose. We see evidence of this law in the delightful effect of a cheerful 

 walk after a depressed or irritated state of mind. Every part of the ner- 

 vous system makes its influence felt by all the rest. A sort of constitu- 

 tional monarchy exists within us ; no power in this small state is absolute 

 or can escape the checks and limitations which the other powers impose. 

 Doubtless the Brain is King, but Lords and Commons have their seats 

 below and guard their privilege with jealous zeal. If the ' constitution ' 

 of your personal realm is to be preserved intact, it must be by the efforts 

 of each parr, lawfully directed to a common end." Hinton on Health 

 and its Condition. 



43. Excess of this activity in disease ? Hydrophobia, etc. ? The difference in severity 

 of the convulsions ? 



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

 in connection with these movements ? 



