17i 



ORDER I. PSEUDOMONADALES 



from that found in true xanthomonads. 

 Likewise none of the three species liquefies 

 gelatin. Neither do they show the gummy 

 growth of true xanthomonads, and they 

 differ in other important characteristics. 

 The second group comprises eleven species 

 which are not pathogenic to plants so far 



as is known. They have been isolated from 

 the surface of leaves, soil and similar ma- 

 terials. All produce a non-water-soluble, 

 yellow pigment, but no one has as yet under- 

 taken a comparative study of cultures to 

 determine which of these species, if any, 

 are true xanthomonads. 



Key to Xanthomonas Addendum. 



I. Plant pathogens. 



A. Non-motile. 



1. Xanthomonas stewartii. 



B. Polar flagellate. 



1. Litmus milk alkaline. Pathogenic on 7ns spp. 



2. Xanthomonas tardicrescens. 



2. No change in litmus milk. Pathogenic on sugar cane, Saccharum officinarum. 



3. Xanthomonas albilineans. 

 II. Saprophytic species. 



A. Gelatin liquefied. 



1. Nitrites produced from nitrates. 



a. Acid but no gas from glucose. 



4. Pseudomonas trifolii. 



5. Pseudomonas xanthe. 

 aa. Action on glucose not recorded. 



6. Pseudomonas caudata. 



2. Nitrites not produced from nitrates. 



a. Litmus milk acid; ferments lactose. 



7. Pseudomonas perlurida. 

 aa. Litmus milk slimy, alkaline. 



8. Pseudomonas ochracea. 



B. Gelatin not liquefied. 



1. Nitrites produced from nitrates. 



a. Do not attack cellulose. 



b. Does not attack phenol. 



9. Pseudomonas cerevisiae. 

 bb. Attacks phenol. 



10. Pseudomonas pictorum. 

 aa. Attack cellulose. 



b. Litmus milk acid but no digestion. 



11. Pseudomonas arguta. 

 bb. No growth in litmus milk. 



12. Pseudomonas subcreta. 



2. Nitrites not produced from nitrates; may or may not hydrolyze agar. 



a. Butter-colored pellicle on litmus milk. 



13. Pseudomonas lacunogenes. 

 aa. No surface pellicle. 



14. Pseudomonas segnis. 



Group I. -Plant pathogens. 

 1. Xanthomonas stewartii (Erw. 

 Smith, 1914) Dowson, 1939. (Sweet corn 

 bacillus, Stewart, N. Y. Agr. Exp. Sta. Bull. 



130, 1897 , 423; Bacterium stewarti (sic) Smith, 

 Bacteria in Relation to Plant Diseases, S, 

 1914, 89; Xanthomonas stewarti (sic) Dow- 

 son, Zent. f. Bakt., II Abt., 100, 1939, 190.) 



