HORSE-BACK RIDING. 91 



six and seventeen, and but seldom at a more ad- 

 vanced period. It is very probable that any influence 

 capable of producing a strong and sudden shock to 

 the nervous system may become an exciting cause of 

 chorea ; thus fright is one of its commonest causes. 

 Irregular dentition, strong mental emotion, blows or 

 falls, the irritation of intestinal worms, etc., etc., all 

 may induce an attack. 



A delicate constitution is a strong predisposing 

 cause. 



In studying the effect of horse-back riding upon 

 anaemia and chlorosis, we saw how the digestive or- 

 gans were aided, the circulation quickened, the ner- 

 vous system strengthened, and the general tone of the 

 body improved. 



In chorea, the co-ordination of muscular power 

 which horse-back exercise requires, together with the 

 moral influence exerted by it upon the sufferer, are 

 added to the beneficent effects before mentioned, 

 and cannot but be of great benefit. We now speak, 

 of course, of the disease in its beginning, when there 

 exists still a certain amount of control over the move- 

 ments of the body. Later on, the violence and 

 irregular nature of the muscular contractions may be 

 almost a bar to sitting on horse-back, yet here even 

 much may be done. 



