156 SCIENCE REMAKING THE WORLD 



ports, cooperation with League mandatories, with the 

 Commission on Opium, and with the Labour Office. 



The fact that great epidemic diseases disregard na- 

 tional boundaries forces upon nations the adoption of 

 cooperative measures against the ravages of these 

 diseases. The first congress in 1851 was called to con- 

 sider ways of dealing with cholera, plague, and yellow 

 fever. The most striking illustration of national 

 cooperation was afforded in 1920 and 1921 by the special 

 commission against typhus in eastern Europe. This 

 campaign was organized under the auspices of the 

 League of Nations and had the direct financial support 

 of fourteen governments. A sanitary barrier was 

 erected in eastern Europe and the march of the disease 

 was halted. There is every reason to expect that co- 

 operation of this sort will become more frequent and 

 that diseases which heretofore have flourished because 

 they encountered only unorganized resistance will now 

 face the united front of a world sanitary army. 



After public-health officers have done all that they 

 can in the way of sanitation and control of contagious 

 diseases, there remains a majority of diseases with which 

 only the individual can deal. A large part of the prob- 

 lem of public health resolves itself into the question of 

 personal hygiene. Only by changing the health habits 

 of millions can the level of national and world efficiency 

 be raised. In attempting this task certain traits of 

 human nature must be reckoned with. All the re- 

 sources of modern education, publicity, and suggestion 

 must be employed. Especially must the habits of 

 children be formed while they are still in a plastic stage. 



