THE HOUSE FLY 



FIG. 7 



The white dots on this disc represent the 

 tracks of one House Fly which was 

 allowed to walk over a small plate covered 

 with gelatine. A few hours later forty- 

 six million germs of typhoid, diphtheria, 

 tuberculosis, and pneumonia were counted. 



FIG. 8 



ENLARGED FOOT OF A HOUSE FLY, showing the 

 claws, hairs, and sticky pad to which disease 

 microbes adhere, often in millions. 

 {Sketch from illustration in " Insects and Disease" by 

 Rennie \V. Doane. Published by Henry Holt and 

 Co., New York.) 



