HOUSEHOLD BACTERIOLOGY 
PART II. 
WORK OF BACTERIA 
When bacterial life first appeared upon the earth 
may never be known, but that it existed thousands of 
years before man made its acquaintance is surely true. 
Indeed, it was within the last quarter of the nine¬ 
teenth century that the knowledge of bacteria became 
of value or was reduced to a science. The problems of 
bacteriology are now being solved very rapidly. What 
future generations may add, who can tell ? 
Although bacteriology is the youngest of all the 
sciences, it occupies a very important place among 
them because of its intimate connection with disease, 
with sanitation or the prevention of disease; with 
successful agriculture, and with the manufacture of 
many products. 
In the eyes of the law every person is considered 
innocent until proved guilty. It may be well for us 
to look at the beneficent role which bacteria play in 
the world, that we may the more justly consider 
their harmful work. We can hardly believe that the 
most numerous forms of life were intended to work 
only harm to man. 
Useful 
Bacteria 
47 
