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 faeces and in 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 giyen of their form and of their 

 movements, and by the figures which accompany 

 these descriptions, 1 that the organisms observed 

 by him are truly Bacteria, Vibrios, and perhaps 

 even Leptothrix. 



In 1773 0. F. Muller endeavored to classify 

 these organisms. He made of them a group of 

 infusoria, under the name of Infusoria crassius- 

 cula, and established two genera, — the g. Monas 

 and Vibrio ; the first characterized as follows : 

 "vermis inconspicuus, 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. 



