334 Journal of Agriczdtural Research voi. xvi, no. 12 



makes the statement that if all small deviations were designated as con- 

 stant characters dozens of species must be established.* 



The organism is much more fully described by Lehmann and Neumann 

 (29, p. 272) under the name of Bacterium fluorescens (the adjective 

 "liquefaciens" dropped to avoid a trinomial, and placed in the genus 

 Bacterium because these authors placed only spore formers in Bacillus). 

 They state that it is identical with B. pyocyaneum in all essential charac- 

 ters.^ It is described as having polar flagella. B. pyocyaneum is described 

 as producing no indol, hydrogen sulphid (HjS), nor gas from dextrose, 

 but as converting nitrate into nitrogen; from which it is to be assumed 

 that B. fluorescens agrees in these characteristics, although nothing defi- 

 nite is said on the subject except in regard to indol and hydrogen sul- 

 phid. Migula (j8) placed this organism in his genus Pseudomonas, 

 created to contain the rods with polar flagella. Migula describes Ps. 

 fluorescens at some length, but lays greatest stress on cultural character- 

 istics and adds little of importance to Kruse's description. Migula 

 gives its diameter as about 0.68 /z. 



Many other writers have described the same or some similar organism. 

 Many different names have been given to fluorescent bacteria from time 

 to time, Tanner (49) having recently stated that 95 different names had 

 been found in a search through the literature. Many of these names are 

 trinomials or worse, such as Bacillus fluorescens putidus Fliigge (26), B. 

 fluorescens liquefaciens minutissimus (Unna) Tommasoli {14) ; but others 

 have conformed to approved rules of nomenclature. The greater number 

 of the fluorescent organisms have been found in water, soil, or decaying 

 organic matter; but one of the best known forms, the pyocyaneus type — 

 more correctly named " Ps. aeruginosa (Schroeter) Migula" — causes blue 

 pus. As mentioned by Kruse (26) , there is great variation among these 

 organisms, and if each variation be taken as a constant characteristic 

 an almost endless variety of species could be named. This fact naturally 

 raises the question how many of the names found in the literature are 

 valid and how many are really synonyms, having been applied to mere 

 physiological variations of a previously described species. Even the blue- 

 pus organism is thought by some writers to be identical with the sap- 

 rophytic forms. We have not yet sufficient data to straighten out com- 

 pletely the resulting confusion, but a careful search through the literature 

 throws a little light on the matter. The information accumulated during 

 the present work has made it possible to review this literature more 

 intelligently than could have been done otherwise; and it seems well, 

 therefore, to summarize the writings of others in regard to some of the 

 more important fluorescent organisms. 



1 Wean man alle kleinen Abweichungen als Konstante Merkmale auffassen wollte, miisste man Dutzende 

 von Arten aufstellen. 



2 Allen wesenUicben Eigenschaften. 



