464 
RESPIRATION AND EXCRETION 
from the drainage of the house and barn. But people in the 
country are not as alert as those in the city and do not give 
as much attention to this important aspect of preserving 
their health as they should. In fact a great many people in 
the city would give no attention to it, were they not com¬ 
pelled to do so by the health laws of their state. Because 
uniform laws are being enforced in our cities and larger towns, 
these places are more healthful to live in than the country 
Figure 411. — A Poor Reservoir. 
Note the open stream that empties into the main body of water. The 
impure water of the Erie Canal drains into this open stream. 
where each one is a law unto himself so far as protecting his 
water supply is concerned. Many people do not understand 
how water can be impure when it looks clear and there is no 
sediment. Nor do they comprehend that the air likewise 
can be impure although it looks clear. We shall soon learn 
that through the studies of technical scientists, there have 
been discovered organisms, which cause sickness, that are so 
small as scarcely to be visible with a microscope. These 
minute organisms live in the air and water and one cannot tell 
anything about the purity of the air or water by looking at it. 
