^ SOIL SCIENCE 



Elevation : Slightly convex. 



Chromogenesis : White nucleus and rim ; remainder semi-transpar- 

 ent grayish white. 



Structure : Grumose. 



Edge : Entire. 

 Peptone cellulose agar, 15 days. 



Form : Round. 



Size : 8 to 12 mm. in 15 days ; in 30 days the colonies frequently 

 attain a diameter of 20 mm. 



Enzymic zone : 1 to 2 mm. 



Elevation : Slightly convex. 



Chromogenesis : Central portion, usually from 5 to 7 mm. in 

 diameter, is j^ellowish white. The central portion of the 

 colony is surrounded by a vitreous zone, which in turn is sur- 

 rounded by a light grayish white rim. 



Internal structure : Granular. 



Edge : Erose. 

 Peptone starch agar, 5 days. 



Form : Irregularly round. 



Size : 5 to 8 mm. 



Enzj'mic zone : 1 to 2 mm. in 5 days ; 3 to 4 mm. in 10 days. 



Elevation : Flat. 



Consistency : Soft in 5 days ; older colonies become firm. 



Chromogenesis : Central portion, usually 2 to 3 mm. in diameter, 

 opaque white. The opaque portion of the colony is surrounded 

 by a vitreous zone, which in turn is surrounded by a thin semi- 

 transparent grayish white rim. 



Internal structure : Granular. 



Edge : Undulate. 

 Beef agar, 5 days. 



Form : Round. 



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



Elevation : Slightly convex. 



Consistency : Soft to butyrous. 



Chromogenesis : Reflected light, grayish white ; transmitted light, 

 the colonies appear as semi-transparent glistening drops. 



Internal structure: Granular. 



Edge : Entire. 

 Potato agar, 5 days. 



Form : Round. 



Size: 1 to 2 mm. 



Elevation : Convex. 



Consistency: Very soft. 



Chromogenesis : Grayish white, frequently develops brownish rings. 



Internal structure : Granular. 



Edge : Entire. 

 11. Filter paper broths, 15 days. Paper is reduced to a loose flocculent mass 



which disintegrates very readily on slight agitation. Paper is de- 

 composed rapidly when the broths contain ammonium sulphate, 



potassium nitrate, peptone, or casein as the source of nitrogen. 



