BACTERIOLOGY IN A NUTSHELL. 
Bacteria 
Explained. 
Saprophytic 
Bacteria. 
Parasitic 
Bacteria 
Our Foes. 
Good 
Bacteria. 
of bacteria to disease” that many people fail to 
discriminate between the bacteria which are our 
friends and those which are our enemies. 
As pupils in the study of bacteriology we learn 
that the term bacteria is applied by scientists to 
the large group of minute vegetable micro-organ-^ 
isms, commonly called “germs” or “microbes.” 
This name was first given to them about the year 
1869, after *Hoffman had demonstrated that 
these tiny mysteries occupied a class by them¬ 
selves, quite distinct from yeast plants and 
moulds with which they had been confused in 
earlier days of bacteriological research. 
All forms of bacteria may be divided into two 
great classes in order to simplify for study. 
These two classes are called the saprophytes, and 
the parasites. The saprophytes, which are the 
friends of all animal life, are many times more 
numerous than the parasites. Parasites are en¬ 
emies to animal life; they are the so-called “dis¬ 
ease germs” or “microbes”; they exist only at 
the expense of other living bodies. They invade 
various parts of the living body and under fav¬ 
orable conditions they weaken and sometimes 
destroy the parts they invade. They take away 
from us substances on which our health is de¬ 
pendent, and deposit in their place that which 
poisons and frequently completely destroys. Be¬ 
cause of their power to produce pathological 
changes in animal bodies, parasitic bacteria are 
also called pathogenic bacteria. 
Saprophytic bacteria are not only our friends, 
but they are of such benefit to mankind that we 
*Hoffman was a German botanist. Born at Roe- 
delsheim, 1819; died at Giessen, 1891. 
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