CHAPTER IX. 



CLASSIFICATION OF THE BACTERIA. 



66. First Attempt by 0. F. Miiller. 



IT has already been mentioned in the Introduction (2) that 

 Leeuwenhoek observed bacteria as far back as the end of the 

 seventeenth century. For a long time, however, nothing more was 

 done than merely to admire the appearance presented by these 

 organisms under the microscope ; and since many of them were 

 observed to exhibit brisk movements, they were considered as 

 animals and denominated animalcula. 



The first to study these organisms from a scientific standpoint, 

 and to arrange and systematise the multitude of forms, some of 

 which were already known, while others were discovered and de- 

 scribed by himself, was the Danish investigator Otto Friedrich 

 Miiller of Copenhagen. In his important work "Animalcula in- 

 fusoria fluviatilia et marina," published in 1786, all the small 

 animals unsuitable for inclusion in Linnseus's sixth class, Vermes, 

 were classed by him under the name of Infusoria (infusion 

 animalcules), and he divided these into two main groups : those 

 provided with external organs and those devoid of same. He also 

 originated the generic names, Vibrio, Monas, and Proteus, still 

 in use. 



The next worker to whom we are indebted for important 

 conclusions respecting the character and species of bacteria is 

 Christian G. Ehrenberg. In his work " Die Infusionstierchen als 

 vollkommene Organismen" (The infusoria as perfect organisms), 

 published in 1838, the generic names Bacterium, Spirocltcete, and 

 Spirillum first occur. He also classed all these organisms with 

 the animal kingdom, by reason of their (frequently very active) 

 spontaneous motion. 



It was left to the Breslau botanist FERDINAND COHN (V.) to 

 ascertain, in 1853, that the organisms we now know as bacteria 

 are of a vegetable nature. This he established by proving the 

 lack of animal organisation, and also from the fact that these 

 creatures increase by subdivision after the manner of the algae, 

 from which they differ, as he says, merely in one characteristic : 

 the absence of chlorophyll. Four years later, NAGELI (V.) be- 

 stowed on these organisms the name of Schizomycetes, which they 

 still retain. 



