218 GENERAL SYSTEMATIC BACTERIOLOGY 



as the principal agency of decay, ("ohne Bacterium termo keine 

 Faulniss")- He described the reaction secured by inoculating the 

 bacteria from putrefying beans into his ammonium tartrate solution 

 and noted the development therein of a green fluorescence. 



Should this description of Cohn be used as fixing the type for Bac- 

 terium as Bacterium termo? The following objections may be raised: 



1. Unquestionably Cohn was dealing with impure or mixed cultures. 

 The fact that when this mixture was inoculated into Cohn's nutrient 

 solution a green fluorescence was produced by no means flxes this as 

 a characteristic of Bacterium termo. Bacteria capable of bringing about 

 this change are widely distributed in nature. In other words, in the 

 heterogeneous mass of organisms present in infusions, known as 

 Bacterium termo, there are included certain fluorescent bacteria capable 

 of growing in Cohn's nutrient solution. The International Botanical 

 Code is explicit on this point : 



Article 51. Every one should refuse to admit a name in the following cases: 

 4. When the group which it designates embraces elements altogether inco- 

 herent or when it becomes a permanent source of confusion or error. 



2. The species Bacterium termo was first described as Monas tertno 

 Mueller, it was tentatively transferred to the genus Bacterium by Ehren- 

 berg, but later rejected by him, and first definitely included in the genus 

 by Dujardin. It was later made a type of the genus Zoogloea by Cohn. 

 Inasmuch as this organism was not at first included in the genus Bac- 

 terium, in fact was definitely excluded by the author of the name, it 

 does not seem advisable to accept it as the type. 



Schroeter (1872, p. 120) put in the genus Bacterium three species 

 of bacteria which had previously been described in other genera, the 

 Vibrio synxanthus^ Ehrenberg (1840, p. 202) he renamed Bacterium 

 synxanthum (the spore bearing rod responsible for yellow milk), the 

 Vibrio syncyaneus Ehrenberg^ (1840, p. 202) he termed Bacterium 

 syncyaneum (the polar flagellate organism of blue milk) and named the 

 Bacterium aeruginosum, the polar flagellate organism of blue green pus. 

 Both of these organisms were later (1886, p. 157) transferred by Schroe- 

 ter to the genus Bacillus. The names used by Schroeter were accepted 

 by Cohn (1872b, p. 173). 



Should one of Schroeter's species be accepted as the generic type? 

 It probably would be inadvisable to designate thus either of the species 



1 The Vibrio xanthogenus, Fuchs (1841, p. 193). 

 " The Vibrio cyanogenus, Fuchs (1841, p. 190). 



