14 THE BACTERIA, 
Although an historical statement of the progress 
of our knowledge of these minute organisms has 
been given in several publications, we think it best 
to make here a new historical summary, which will 
be completed by an indication of the principal pa- 
pers relating to them which have been published 
recently. 
The first observer who perceived bacteria was 
Leeuwenhoeck. As early as 1675, while examin- 
ing by chance with his magnifying glasses a drop 
of putrid water, the father of microscopy re- 
marked with profound astonishment that it con- 
tained a multitude of little globules, which moved 
with agility. The following year he recognized 
the presence of bacteria in feces and im tartar 
from the teeth; and, if he has not named them, 
it is easy to assure one’s self by the description 
which he has given of their form and of their 
movements, and by the figures which accompany 
these descriptions,’ that the organisms observed 
by him are truly Bacteria, Vibrios, and perhaps 
even Leptothriz. 
In 1773 O. F. Miiller endeavored to classify 
these organisms. He made of them a group of 
infusoria, under the name of Jnfusoria crassius- 
cula, and established two genera, —the g. Monas 
and Vibrio; the first characterized as follows: 
“vermis imconspicuus, simplicissimus, pellucidus, 
punctiformis,’ comprising the following species: 
Monas termo, atomus, punctum, ocellus, lens, mica, 
1 Leeuwenhoeck. Opera omnia, Lugd. Batav., 1722, 11, p. 40, fig. A to G. 
