HOUSEHOLD BACTERIOLOGY 
Dust as 
Source 
of Danger 
Summary 
of Special 
Terms 
114 
possessions or the few that may bring disease to her 
family. 
In general the harmful bacteria and other forms are 
brought into her house as dust, which through some¬ 
body’s ignorance or criminal carelessness, is allowed 
to scatter itself ; dust allowed to collect in dark warm 
places, to be blown about by wind; dust rising from 
dried expectorated matter on sidewalks, floors or fab¬ 
rics, from drainage infected soil, possibly carried to 
the water or food supplies. 
It used to be said that dirt was matter in the wrong 
place. We see now that dangerous dirt is simply a 
certain kind of matter in the wrong place. It is in¬ 
deed, filth , because this dirt' is alive it must not be 
allowed to grow under any conditions which may bring 
harm to man. 
A summary of a few special terms explained in the 
text may serve as a review. 
Fermentation from a physiological standpoint is the 
result of growth in organic matter of a living organ¬ 
ized ferment. 
Alcoholic fermentation is usually brought about by 
yeasts. A few bacteria and molds are found to be 
capable of making weak alcoholic solutions. 
Fermentation is applied to the process when the 
products are desirable or agreeable and non-poisonous. 
Putrefaction is fermentation carried so far or under 
such conditions that the products are undesirable, dis¬ 
agreeable, foul smelling and poisonous. 
