148 



II. THE EVOLUTION OF VIRUSES 



months. Also with Europeans living in their native countries the 

 same is the case. In most cases with Europeans two peaks are found 

 as with Japanese in Aomori. 



1 2 34 567 8 9 10 11 12 12 



Months of infection 



Fig. 19. The seasonal change in the incidence of measles in various 

 regions. I : Shanghai. II : Cleveland. Ill : Wien. IV : Hamburg. 

 V : Liibeck. 



Fig. 20. The seasonal change of human impregnation in various parts 

 of Japan. I : Nagasaki. II : Iwate. Ill : Hokkaido. IV. Aomori. 



