CHAPTER II. 
THE RELATION OF BACTERIA TO DISEASE-BACTERIA 
IN PROCESSES OF NATURE. 
Revelations 
of the 
Microscope. 
Mysteries concerning the origin of numerous 
diseases, which must otherwise have remained 
mysteries forever, have been made more or less 
clear since the perfecting of the microscope. 
Prior to the revelations made by the use of this 
instrument, very little was positively known con¬ 
cerning the formation of the various elements of 
which the machinery of the human structure is 
made up and by which it is kept in running 
order. Now scientists are able to trace the 
Cell 
Formation. 
human body back to the time when it 
was but a single cell, from this single 
cell to watch its growth and development 
into innumerable single cells, to see the single 
cells fold into layers, these in their turn 
to form the groups of cells out of which the 
various bones and muscles and nerves and tubes 
Organs and 
System. 
and tissues of the body are composed. These 
groups we call the organs and systems of the 
body. Each has its own work to perform, and 
each exists to a certain extent independently of 
the other. Yet all are so intimately related and 
connected in their efforts to maintain life and 
health that when disease comes to one group of 
cells composing a system, other groups compos¬ 
ing other systems suffer also. 
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