86 MICROBES, FERMENTS, AND MOULDS. 
lower forms, which have been by some united in the 
kingdom Protista, 
Microbes, or bacteria (Schizophyta or Schizomycetes), 
appear, in liquids examined under the microscope, as 
small cells of a spherical, oval, or cylindrical shape, 
sometimes detached, sometimes united in pairs, or 
in articulated chains and chaplets (Fig. 
P re F 48). The diameter of the largest of these 
o? a cells is two micro-millimetres, and that 
* a of the smallest is a fourth of that size, 
Fig. 42--Ferment 8° that at least 500 of the former and 
dane (ye 2000 of the latter must be placed end 
faeat forme of to end in order to attain the length of 
aor nisheplets amillimetre. Itis therefore plain that a 
ae magnifying power of 500 to 1000 dia- 
meters, or even still higher, is required to make these 
beings clearly visible under the microscope. 
One very common bacterium may be found every- 
where, and can be easily procured for microscopic 
observation: Bactervwm termo, or the microbe of im- 
pure water. This bacterium is not injurious to health, 
since there is no potable water in which it is not 
found in greater or less quantity. In order’ to obtain 
numerous specimens, it is enough to take half a glass 
of ordinary water from a spring or river, and to leave 
it.for some days on a table or chimney-piece, the 
vessel being uncovered to allow the access of air. We 
may soon observe that a thin coating is formed on 
the surface of the water, which looks like a deposit 
