164 HOUSEHOLD BACTERIOLOGY 
fresh from the fire. The purest milk obtainable for 
the table contains thousands of bacteria to the cubic 
centimeter, while commercial milk may have many 
millions. Buttermilk and other forms of acid milk 
also contain correspondingly large numbers. Many 
hundreds jof these harmless bacteria are known and 
named, while the harmful or pathogenic bacteria 
number only a few score. It is these few malevolent 
microbes that must be avoided, and hence all tho 
precautions we have -adopted as to cleanliness in 
hospital, market, dairy and kitchen. But if life is to 
be worth living we must learn where these objection¬ 
able varieties come from in order to concentrate at 
the proper place our use of that eternal vigilance 
which is the price of health. 
Here are a few suggestions. Human contact with 
food is probably the greatest source of danger. If a 
piece of dry bread fall on the floor of a clean private 
house the bacteriologist teils us it might be picked up 
and eaten with impunity. Not so if this bread were to 
be dropped on the floor of a trolley car, especially in the 
old days when expectoration was common. The 
driver’s hand which grasps the top of the milk bottle 
which he delivers may leave bacteria there and the 
bottle should be washed before the milk is poured 
out. The diminishing of the number of bacteria in 
our food by the practice of cleanly habits (and no one 
of these habits is more important than the thorough 
washing of the hands before handling and preparing 
food and before meals) is recommended by all hygien¬ 
ists ; but there should be no morbid fear of the con¬ 
sumption of foods that have been the dependence of 
the race since the dawn of civilization and before, 
simply because we do not ordinarily eliminate from 
them every trace of bacterial life. 
