THE PREVENTION OF INFECTIOUS DISEASE. 409 



consequent falling off in quantity works little 

 more than injury. Coffee, tea and alcohol are 

 no drinks for children. The story of the 

 youth who when questioned as to the virtues 

 of the old Germans declared them to be " Treue, 

 Wahrheitsliebe uiid Gastwirthschaft " is in 

 perfect accord with the present customs of both 

 children and adults. Our educated youth, in- 

 stead of fuddling themselves and killing time 

 in smoky rooms with skat-playing, would do 

 better to develop themselves in mind and man- 

 ners and to keep the body strong by gymnas- 

 tics, sports and athletic games. I need only 

 mention this to call attention to a common error 

 of omission. The body that is trained and 

 hardened by exercise is more resistant to 

 disease in general, as Pettenkofer and G. 

 Jager have shown. The flushing out of the 

 body by training, with the consequent increase 

 in its specific weight, is, as G. Jager rightly re- 

 marks, an important method of obtaining im- 

 munity. To the same end a proper habituation 

 to the feeling of thirst is very important, be- 

 cause otherwise this feeling leads to excess in 

 drinking, and to drinking at the wrong times. 

 The regulation of diet in training in the more 

 limited sense should never be carried out ac- 

 cording to a fixed scheme. The human being 

 does not possess like the carnivora, degenerate 



