Chapter III 
Are there 
microbes 
everywhere? 
THE MICROBES IN AIR AND WATER 
M ICROBES are so small that they float in 
the air and are blown about by the winds 
for a long time. It is almost impossible, at least 
in places where people and animals live, to find 
air that does not contain them. There are fewer 
microbes in the air of the country than of the 
city; there are fewer in mountain air than in 
the air of the lowlands; and the air of the mid¬ 
ocean, where no human beings or animals live, 
is almost free from them. We find that the 
more human beings there are, the more mi¬ 
crobes there are in the air; a room filled with 
people has many more in the air than an un¬ 
occupied room. 
Of course, wherever there is dust in the air, 
there are microbes with it; the more dust there 
is, the more microbes there are. This would 
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