SANITATION 



97 



chairs, shelves, etc. Figure 45, redrawn from Dust 

 and Its Dangers, T. Mitchell Prudden, shows how the 

 living plants attach themselves to the other particles 

 of dust ; a is a small bit of wood carrying four different 





. 45. COLONIES OF BACTERIA GROWING ON DUST PARTICLES. 

 (After Prudden.) 



colonies ; b is a grain of sand surrounded by one col- 

 ony ; c a splinter of wood, is loaded with five different 

 species. Each of these colonies is the growth of five 

 days from a single germ which fell on the surface of 

 the gelatine. At the end of five days the largest was 

 only just visible to the naked eye. 



If a dust-garden be planted immediately after 



Sweeping 



