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 
