216 GENERAL SYSTEMATIC BACTERIOLOGY 



It is of interest to note that many subsequent writers ascribe the 

 species Bacterium termo to Dujardin. 



Diesing (1850, p. 14) gives the following generic description of 

 Bacterium. 



Corpus nudum, lorica destitutum head mutabile, cylindricum subovatum aut 

 subglobosum, partitione imperfecta uniseriali, multiplici, transversa in synther- 

 ium lineare, moniliforme, rigidulum, rectum, hyalinum accrescens. Flagellum 

 in articulo primo terminale simplex. Ocellus nuUus. 



Perty (1852, p. 179) developed a classification of the infusoria, recog- 

 nizing a family Vibrionida with two subfamilies Spirillina and Bac- 

 terina. Under the latter the genera Vibrio, Bacterium, Metallacter 

 and Sporone^na are included. Vibrio is defined as flexuous. Bacterium 

 is non-flexuous. The only species of Bacterium described is Bact. 

 termo ascribed to Dujardin. It is recorded as occurring "in den aller- 

 verschiedensten faulenden Aufglissen und Sumpfwassern das ganze 

 Jahr." He notes that it was recorded by Dujardin "im Eiter und an- 

 dern pathologischen Fliissigkeiten" and even "nach Leeuwenhoek im 

 Zahnschleim." The description is wholly unsatisfactory, and shows a 

 tendency, which became more pronounced during the succeeding two 

 decades, to call all organisms associated with putrefaction and decay 

 Bacterium termo. 



Cohn (1854, p. 123) for the first time definitely grouped the form now 

 termed bacteria under the plant kingdom, removing them from the 

 Infusoria. He studied at length the Bacterium termo Dujardin, which 

 he regarded as a synonym of Vibrio lineola Ehrenberg, He concluded 

 this form to represent merely the swarm cell state of an alga-like fungus. 

 He was unable to see the "cilia." He gave it the generic name Zoogloea 

 with the following characters: 



Cellulae minimae, bacilliformes, hyalinae, gelatina hyalina in masses mucosas 

 globosas, uvaeformes, mox membranaceas consociatae, dein singulae elapsae, 

 per aquam vacillantes. 



The species became Zoogloea termo. As synonyms he notes "Pal- 

 mella infusionum Ehr., Micraloa teres V. Flotow, Bacterium termo 

 Dujardin and Vibrio lineola Ehrenberg. 



Several authors in the next two decades followed Cohn in the sub- 

 stitution of Zoogloea for Bacterium. For example, Rabenhorst (1865, 

 p. 35) in his "Flora Europaea Algarum" includes this genus among the 

 algae under the heading "Formae achroae, hyalinae {mea sententia ad 



