312 BRIEF HISTORY OF BACTERIOLOGY UP TO 1881 



ones remained for Winogradsky in 1889. Thus the belief 

 that fermentation and putrefaction are due to microorgan- 

 isms was as well established by the early eighties of the last 

 century as that similar organisms are the causes of infectious 

 diseases. 



STUDY OF FORMS. 



An important part of the scientific knowledge of living 

 organisms is dependent on a study of their forms and rela- 

 tionships. As has been stated, Leeuwenhoek considered 

 bacteria to be '' animalcules" because they showed inde- 

 pendent movement. But little attention was paid to the 

 natural history of these animalcules for nearly a hundred 

 years after Leeuwenhoek. During the last quarter of the 

 eighteenth century, however, workers busied themselves 

 chiefly with the discovery and description of new forms. 

 Among these students w^ere Baron Gleichen, Jablot, Lesser, 

 Reaumur, Hill and others. Muller, of Copenhagen, in 1786 

 published the first attempt at classification, a most impor- 

 tant step in the study of these organisms: Muller intro- 

 duced the terms Monas, Proteus and Vibrio, which are 

 still in use. Ehrenberg, in his work on Infusoria, or the 

 organisms found in infusions, published in 1838, introduced 

 many generic names in use at present, but still classed the 

 bacteria with protozoa. Joseph Leidy, the American natu- 

 ralist, considered that the "vibrios" of previous writers were 

 plants and not "animalcules." He seems to have been the 

 first to have made this distinction (1849). Perty (1852) 

 recognized the presence of spores in some of his organisms. 

 Ferdinand Cohn (1854) classed the bacteria among plants. 

 Nageh (1857) proposed the name " Schizomycetes" or 

 "fission fungi," which is still retained for the entire class of 

 bacteria. Cohn in the years 1872-1875 established classifi- 

 cation on a modern basis and added greatly to the knowledge 

 of morphology and natural history of bacteria. He described, 

 spore formation and the development of spores into active 

 bacteria, and showed the close relationships as well as dif- 

 ferences between the bacteria and the lower algse. Robert 

 Koch was a pupil of Cohn. 



