THE DECOMPOSITION OF CELLULOSE IN SOILS 465 



Potato agar, 5 days. 



Form : Round. 



Size : 2 to 3 mm. ; bottom colonies are no larger than the surface 

 colonies. 



Elevation: Decidedly convex; in 10 days colonies frequently be- 

 come somewhat unbilicate. 



Consistency : Butyrous. 



Chromogenesis : Semi-transparent, glistening, light grayish white 

 to almost vitreous. Many colonies exhibit a pearl-like luster. 



Internal structure: Finely granular. 



Edge : Entire. 



10. Filter paper broths, 15 days. Paper is reduced to a white pulp-like mass 



made up of very short disintegrated fibers which become dis- 

 tributed through the solution on slight agitation. The paper is 

 decomposed very rapidly with ammonium sulphate, potassium 

 nitrate, and peptone as the source of nitrogen. The decomposi- 

 tion takes place more slowly when casein is added as the source 

 of nitrogen. 

 III. Biochemical Features. 



11. Dunham's solution, 10 days. No ammonia produced ; nitrite produced. 



12. Starch nitrate solution, 10 days. No ammonia produced ; no nitrite pro- 



duced. 



13. Peptone nitrite solution, 10 days. Indol produced. 



14. Carbohydrate broths, 12 days. No gas produced. Per cent of acidity 



(Fuller's Scale) with: Dextrose, 1.10; Lactose, .80; Saccharose, 

 1.00; Maltose, 1.20; Glycerine, .40; Mannite, .05; Starch, 1.20. 



Pseudomonas arguta, n. sp. 

 Source: Soil from Azusa, California; and Whittier, California. 



I. Morphology. 



1. Vegetative cells : Average dimensions .8 x .3 ft.. 



2. Endospores : None observed. 



3. Flagella : 1 to 2 in number ; 6 to 8 /x in length. 



4. Staining reactions : Gram negative. Stains readily with the anihne 



dyes. 



II. Cultural Characteristics. 



5. Agar strokes, 5 days. 



Beef agar: Scant, grayish white, filiform growth. 

 Potato agar: Moderate, yellowish, glistening white. 

 Peptone starch agar: Scant, white to grayish white. 



6. Potato cylinders, 30 days. No growth. 



7. Gelatin stab: Moderate yellowish growth at surface and along the 



track of needle in 10 days ; no liquefaction in 30 days. 



8. Beef broth, 5 days : Clouded. 



9. Litmus milk: Reddened in 4 days; neither coagulated nor digested in 



30 days. 

 10. Plate cultures. 



Ammonia cellulose agar, 15 days. 

 Form : Round. 



Size : Surface colonies, 1 to 2 mm. ; bottom colonies, 3 to 4 mm. 

 Enzymic zone: 1 mm. or less in 15 days; in 30 days the zone fre- 

 quently becomes 2 or 3 mm. 



