126 
novel methods, established not merely the 
fact that living ferments in general are the 
_ cause of fermentation in general, but, what 
was of equal or even greater importance, 
the existence of specific or characteristic 
ferments for particular fermentations, one, 
for example, producing the alcoholic fer- 
mentation, another the lactic, a third the 
butyric, a fourth the acetic, and so on. If 
to-day we have to modify this primitive 
simplicity of arrangement and refer rather 
to one group of ferments than to one 
species merely, nevertheless the idea of 
specific energies for specific ferments re- 
Mains secure and underlies most of the 
practical work of bacteriology. 
Finally, through his work on industrial 
micro-biology, on the yeasts and the fer- 
ments of milk, vinegar, etc., Pasteur was 
led not only to consider the applications of 
bacteriology to the useful arts, but also to 
study the ailments of fermented drinks and 
the causes of their deterioration or ‘ dis- 
ease,’ with the result that in discovering 
and proclaiming the sources of the diseases 
of wine and beer as residing in specific 
noxious ferments or germs carelessly or un- 
wittingly introduced, he became, almost un- 
consciously, not merely the apostle and de- 
fender of the biological or germ theory of 
fermentation, but also the principal con- 
¢emporary exponent of the biological or 
germ theory of disease; a theory which had 
long been a dream of pathologists and now 
suddenly rose into scientific as well as pop- 
ular favor. 
. Such was the origin of bacteriology, and 
such were some of the early achievements 
of its great founder. Stimulated by the 
work of Pasteur, a host of eager and en- 
thusiastic workers threw themselves with 
intense zeal into the study of the micro-or- 
ganisms which constitute the field of micro- 
biology. Time has proved beyond all perad- 
yenture that the foundations laid by Pasteur 
were laid solidly and securely. The fermen- 
SCLENCE. 
[N. S. Von. XIII. No. 317. 
tations are in fact what he and his precursor 
Schwann believed them to be, viz., chem- 
ical changes produced by living ferments, 
which, taken together, we may call mi- 
crobes. Putrefactions are, as Pasteur be- 
lieved them to be, essentially anaérobic 
fermentations. Present-day spontaneous gen- 
eration is, a8 Pasteur claimed, a myth—the 
last survivor of the notions of the alehem- 
ists. Organic decomposition and decay in na- 
ture have been found to be simply slow fer- 
mentations and putrefactions. Nitrification, 
or the natural mineralization of organic 
matter, is essentially an oxidizing fermen- 
tation, as is also, for example, the making 
of vinegar, from alcoholic cider. The infec- 
tious or zymotic diseases are either harmful fer- 
mentations, or the results of such fermen- 
tations, occurring not merely in wine, beer 
and vinegar, but, as Pasteur himself showed 
in the case of the silk-worm, in or upon the 
animal—and, we may now add, the plant 
—body. 
A careful review of the subject from our 
present relatively advanced position shows 
that the really distinguishing characteristic 
of bacteriology is not merely its subject 
matter but its methods, not so much the pe- 
culiar organisms with which it deals—in- 
teresting and important though these are 
—as the peculiar means it has devised and 
employed for studying these organisms. In 
this respect bacteriology differs widely from 
any other science bearing the name of a 
particular class of plants or animals. Sci- 
ences such as mammalogy, ornithology, en- 
tomology, dendrology, pteridology, bryol- 
ogy, algology, mycology, lichenology and 
the like are chiefly, though not exclusively, 
characterized by the peculiarities of the 
special forms of life with which they deal, 
the methods by which they are pursued be- 
ing largely common to all or at least in no 
great degree either peculiar or extraordi- 
In bacteriology, on the contrary, 
owing, no doubt, to the small size and ap- 
nary. 
