GENERAL SYSTEMATIC BACTERIOLOGY 217 



fungos referendae") . The generic description given is identical with 

 that of Cohn. The single species Zoogloea termo (Miiller) Cohn is 

 briefly described as : "Z. thallo gelatinoso globoso, cellulis liberis mobili- 

 bus, rectis, 1/2000-1/700" aequantibus. Hab. in aquis stagnantibus, 

 imprimis corruptis ubique." 



A Zoogloea ramigera was later described by Itzigsohn (1867, p. 414). 



The next author of note defining Bacterium was Davaine (1864, 

 p. 629) who, like Cohn, separated the Vihriones from the protozoa, 

 and described the genera Bacterium, Vibrio and Spirillum. His defini- 

 tion of Bacterium (given in 1868, p. 68) is identical with that of Dujar- 

 din. It should be noted that this author emphasized the importance 

 of motility in the generic diagnosis. 



An interesting sidelight on the utilization at this time of the term 

 Bacterium termo to include the greatest variety of microorganisms is to 

 be found in the writings of Liiders (1866, p. 36) who concluded that this 

 wide spread organism was a growth stage of a fungus. Hallier (1886) 

 introduced and developed his theory of pleomorphism which reached 

 its culmination in the work of Billroth (1874). This led to general dis- 

 trust at this time in the existence of true bacterial species and indi- 

 rectly contributed to the lack of regard for the rules of nomenclature 

 during the next several decades. 



Davaine (1868, p. 21) used the name in the sense of Dujardin. differ- 

 entiating the non-motile forms such as the anthrax bacillus in the new 

 genus Bacteridium. His description of Bacterium is as follows: 



Genre Bacterie. Bacterium (Ehrenberg, Dujardin). Corps filiforme, roide, 

 devenant plus ou moins distinctement artieule par suite d'une division spontanee 

 imparfaite; mouvement vacillant, non ondulatoire (Dujardin). 



In summary, to the year 1872, the generic name Bacterium was not 

 applied to any species which can now be recognized satisfactorily. The 

 original Bacterium triloculare Ehrenberg was no longer recognized in 

 the literature. Bacterium, termo the organism found commonly in 

 putrefying solutions was the only species. 



Cohn (1872, p. 167) rather radically emended the previous generic 

 descriptions of Bacterium to include those rod-shaped organisms in 

 which the cells are short, never filamentous. He made it the sole repre- 

 sentative of his tribe Microbacteria. The cells are short cylindric 

 or elliptical, never in chains or filaments, often forming firm zooglocal 

 masses, alternating motile with non-motile stages. His description was 

 largely based on his conception of Bacterium termo, which he regarded 



