BACTERIA IN WATER 95 



its action upon the pathogenic bacilli — those of tubercle and 

 typhoid — with the result that these infective bacteria have 

 been completely destroyed. It appears that such destruc- 

 tion of infective germs occurs in the tank, and depends in 

 degree upon the rapidity with which sewage is passed 

 through the tank. The cultivation beds also have an 

 inimical effect upon infective bacteria. Hence the final 

 effluent is practically germ-free as regards pathogenic 

 organisms. 



