THE DECOMPOSITION OF CELLULOSE IN SOILS 459 



Plate cultures. 



Ammonia cellulose agar, 15 days. 

 Form : Irregularly round. 

 Size: 1 to 1.5 mm. 

 Enzymic zone: 1 to 1.5 mm.; in 30 days the enzymic zone may 



attain a diameter of 2.5 mm. 

 Elevation : Slightly convex. 



Chromogenesis : Opaque white or light grayish white. 

 Internal structure: Granular. 

 Edge : Undulate. 

 Peptone cellulose agar, 15 days. 

 Form : Irregularly round. 

 Size: 1 to 1.5 mm. 

 Enzymic zone : .5 to 1 mm. ; in 30 days the enzymic zone may 



reach a diameter of 2 mm. 

 Elevation : Slightly convex. 

 Chromogenesis: White nucleus and rim, remainder of colony 



grayish white. 

 Internal structure: Nucleus and rim made up of coarse compact 



granules, remainder of colony finely granular. 

 Edge : Undulate. 

 Peptone starch agar, 5 days. 

 Form : Irregularly round. 

 Size: 7 to 10 mm. 



Enzymic zone: 1 to 1.5 mm. in 5 days; 2.5 to 3 mm. in 10 days. 

 Elevation : Flat or slightly convex. 

 Consistency : Firm. 

 Chromogenesis: Grayish white cottony-like colony in 5 days; in 



10 days colonies become distinctly grayish. 

 Internal structure: Coarsely granular. 

 Edge : Lancelate. 

 Beef agar, 5 daj's. 

 Form : Round. 



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

 Elevation : Slightly convex. 



Consistency : After 5 days colonies are soft ; after 10 days, brittle. 

 Chromogenesis: Very small white nucleus, remainder of 

 colony grayish white. Surface colonies exhibit a pearl-like 

 luster. 

 Internal structure: Granular. 

 Edge : Entire. 

 Potato agar, 5 days. 



Form : Surface colonies round ; bottom colonies irregularly round. 

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

 Elevation : Convex. 

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



rous. 

 Chromogenesis: Light grayish white, semi-transparent colonies 



with a pearl-like luster. 

 Internal structure: Made up of fine granules, loosely arranged. 

 Edge : Entire. 



