THE DECOMPOSITION OF CELLULOSE IN SOILS 461 



Chromogenesis : Opaque white to light grayish white. 



Internal structure : Coarse granules, compactly arranged. 



Edge : Lobate. 

 Peptone starch agar, 5 days. 



Form : Irregularly round. 



Size : 1 to 2 mm. 



Enzymic zone: 1 to 1.5 mm. in 5 days; 2 to 2.5 mm. in 10 days. 



Elevation : Convex ; frequently somewhat pulvinate. 



Consistency : After 5 days the colonies are soft ; older colonies 

 become somewhat viscous. 



Internal structure : Granular ; granules frequently arranged in 

 clumps. 



Edge : Lobate. 

 Beef agar, 5 days. 



Form : Round. 



Size: Surface colonies 1 to 1.5 mm.; bottom colonies 2 to 3 mm. 



Elevation : Convex. 



Consistency: Soft; becomes brittle after 10 days. 



Chromogenesis: Grayish white pearl-like luster. By transmitted 



light the colonies appear as semi-transparent glistening drops. 



Internal structure: Granular. 



Edge : Entire. 

 Potato agar, 5 days. 



Form : Surface colonies, round ; imbedded and bottom colonies, 

 irregularly round. 



Size : 2 to 3 mm. 



Elevation : Pulvinate. 



Consistency: After 5 days colonies are soft; after 10 days, buty- 

 rous or brittle. 



Chromogenesis: Reflected light, yellowish to grayish white; trans- 

 mitted Hght, semi-transparent glistening drops. 



Internal structure : Coarsely granular. 



Edge : Entire. 



10. Filter paper broths, 15 days. Paper is reduced to a thin limp sheet 



which falls apart on slight agitation. Solutions containing ammo- 

 nium sulphate, potassium nitrate and peptone as the source of 

 nitrogen show a rapid decomposition of the paper. Solutions con- 

 taining casein showed only a slight decomposition of the paper 

 even after 30 days' incubation. 

 III. Biochemical Features. 



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



12. Starch nitrate broth, 10 days. No ammonia produced; nitrite produced. 



13. Peptone nitrite solution, 10 days. No indol produced. 



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



(Fuller's Scale) with: Dextrose, 1.60; Lactose, 1.20; Maltose, 

 1.40; Mannite, .00; Saccharose, 1.30; Glycerine, .70; Starch, 1.40. 



Bacterium hicrosum, n. sp. 



Source: Soil from Redlands, California; and Upland, California. 

 I. Morphology. 



1. Vegetative cells: Average dimensions 1.3. x .4 p,. 



2. Endospores : None observed. 



