Chart No. 7.— SHOWING, BY CURVES, ABUNDANCE OF FLIES (MU SC A DOMESTICA) IN RELATION TO THE PREVALENCE OF TYPHOID FEVER. 
-a™ „ Cases due to direct contact with previous cases and those due to milk infection are not included, only the unaccounted-for cases being charted. 
Seasonal abundance of flies, fourteen-dav averages (Howard’s data). 
Seasonal prevalence ot typhoid fever, fourteen-day averages (our data). 
BULLETIN 52, HYGIENIC LABORATORY, 
