terested almost nobody,
but when, however, it was shown that putrefaction of meat is due to
the agency of the _bacterium termo_, and the decomposition of albumen
to the _bacillus subtilis_; when anthrax in cattle and sheep was found
to depend on the _bacillus anthracis_, and that in human beings it
caused malignant pustules; when suppuration of wounds was found to be
associated with micrococci; and when it was announced that by a
process of inoculation cattle could be protected against anthrax, and
that by carbolic spray and other well known precautions the
suppuration of wounds could be prevented--all the world lent its ears
and investigation at once began.

Because labors in bacteriology promised to be fruitful in practical
results, the workers speedily became innumerable, and we are
accumulating a wondrous store of facts. How long now is the list of
diseases in which germs make their appearance--in pneumonia, in
endocarditis, in erysipelas, in pyaemia, in tuberculosis, and so on and
so on. One of the most striking illustrations is the gonococcus of
gonorrhoea, whose presence in and around gives to the pus cells
their virulent properties, and when transferred to the eye works such
lamentable mischief. Without their existence the inoculation of pus in
the healthy eye is harmless; pus bearing the gonococci excites the
most intense inflammation. Similar suppurative action in the cornea is
often caused by infection of cocci. The proof of causation may be
found in the fact that the most effective cure now practiced for such
suppuration is to sterilize them by the actual cautery. Rosenbach says
that he knows six distinct microbes which are capable of exciting
suppuration in man. Their activity may be productive of a poison, or
putrefactive alkaloid, which is absorbed.

There are at present two prominent theories in regard to the
infections which produce disease. The first is based upon chemical
processes, the second upon the multiplication of living organisms. The
chemical theory maintains that after the infectious element has been
received into the body it acts as a ferment, and gives rise to certain
morbid processes, upon the principle of catalysis. The theory of
organisms, or the germ theory, maintains that the infectious elements
are living organisms, which, being received into the system, are
reproduced indefinitely, and excite morbid processes which are
characteristic of certain types of disease. This latter theory