GENERAL SYSTEMATIC BACTERIOLOGY 229 



based the genus upon the type of movement of the cell. Today, he 

 states, we know the characteristic type of motion to be due to the pres- 

 ence of polar flagella on short rods. He concludes that the Bad. termo 

 is closely related to Bad. pyocyaneum and accepts this as the type of the 

 genus. His result is a genus practically identical with that proposed 

 by Smith. 



A somewhat similar conclusion will be reached as the result of the 

 examination of still another line of evidence, a study of the species of 

 Bacterium other than Bad. termo recognized by Cohn and his associates. 

 Three species previously known were placed in the genus Baderium by 

 Schroter. One of these was named Vibrio syncyaneus by Ehrenberg 

 (1840, p. 202), Vibrio cyanogenus by Fuchs (1841, p. 190) and Baderium 

 syncyaneum by Schroter. It is the organism which has been repeatedly 

 described as the cause of a blue coloration in milk. It has the morphol- 

 ogy characteristics of the genus Pseudomonas of Migula. The species 

 Bad. aeruginosum of Schroter is the earlier name of the blue pus organ- 

 ism variously called Bacillus pyocyaneum, Pseudomonas pyocyaneas and 

 Pseudomonas aeruginosa, and chosen by VuiUemin under the name 

 Bad. pyocyaneum to constitute the type of the genus. The Bad. brun- 

 neum resembles the two preceding in the formation of a water soluble 

 pigment. The Bact. xanthinum, or as it now more commonly known, 

 Bacillus synxanthus is an organism which is frequently recorded as the 

 cause of orange or yellow milk. It does not appear to belong to the same 

 group with the other forms. It would seem that at least two and prob- 

 ably three of the organisms recognized by Cohn and Schroter in addi- 

 tion to the Bad. termo forms which can be recognized today and studied 

 readily, would conform to the generic diagnosis used bj' E. F. Smith and 

 by Vuillemin. 



A serious objection to this conception of Baderium is the emphasis 

 placed upon the flagella and motihty. Smith would include, for in- 

 stance, in his genus Bacterium, a green fluorescent monotrichiate rod 

 but would exclude from the genus another organism which produced 

 the same green fluorescence, had similar colonies and growth reactions 

 in the various media, which in short, was culturally, physiologicallj', 

 and morphologically identical except that it was non-motile. A genus 

 ought not ordinarily to be constituted upon one character alone. It 

 should group together closely related organisms. Disobedience to this 

 principle would require the botanist to remove the Lombary poplar 

 from the genus Populus because of its constant failure to produce the 

 seeds and fruits characteristic of the genus. Conformity with all other 



