CHAPTER III. 
MICROBES, STRICTLY SO CALLED, OR BACTERIA. 
I. Tae VEGETABLE NatTure or MICROBES. 
As we have seen in the preceding chapter, there is 
no well-defined limit between ferments and bacteria, 
any more than between ferments and fungi, or, again, 
between fungi and bacteria. Their smaller size is the 
principal difference which separates bacteria from 
ferments, since in other respects these two classes are 
for the most part alike in form and organization. There 
are bacteria of large size, such as Leptothria bucealis, 
so frequently found in the mouth even of a healthy 
man, which much resembles in its mode of growth 
some of the lower fungi, such as Oidiwm albicans. 
Yet the latter is regarded as a fungus, and the former 
as an alga, by our best eryptogamous botanists. It 
may, however, be said that the two classes of algz and 
fungi are connected with each other by their lower 
forms, and probably have a common origin ; just as the 
two great organic kingdoms are connected by their 
