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The fact that many diseases of the human body are known to 
be caused by bacteria is likely to give to this group of plants 
(for plants they are) a reputation which they do not rightfully 
deserve, for these organisms are really of great service to the 
world. In the commercial world they are made use of in many 
ways: the process of fermentation and the et ee of 
alcohol is ee upon the action of bacteria; in the cheese 
industry they play an important part, and are employed in the 
manufacture of many dyes. Perhaps one of the chief services 
of the bacteria is in their relation to decay. The process of decay 
is a very important one, and were it not for the action of bacteria 
in reducing complex materials to their simple form the surface 
of the earth would become encumbered with the remains o 
dead animals and plants. In this alone, they atone for any evil 
which may be charged to them. The fact that a few forms 
have become parasitic upon the human body, bringing about 
disease and death, is of vast importance to us, but so far as this 
group of plants is concerned <t is only an incidental matter, for 
there are comparatively few which act in this manner. 
There is another group of lower plants which is of vast impor- 
tance to us on account of their relation to animal and plant 
diseases, more especially to plant diseases. These plants are 
known as fungi, mildews or moulds. The fungi bear about the 
same relation to plant diseases which bacteria hold to diseases 
of animals. While many diseases of the animal body are caused 
by bacteria, ae ean few are caused by fungi. On the other 
and, while y diseases among the ae kingdom result 
from fungi, petiaenctaiie few. are known to be caused by 
bacteria. The fungi may be considered one a the chief causes 
of plant diseases. 
From a physiological point of view the fungi are identical with 
g t 
like bacteria they may be either parasitic or saprophytic. The 
chief differences between fungi and bacteria are in their structure 
and reproduction. Instead of isolated, minute, motile bodies the 
fungi consist of a mass of delicate, simple or branching threads. 
