462 SOIL SCIENCE 



3. Staining reactions : Gram negative. Stains readily with the aniline 



dyes, 

 II. Cultural Characteristics. 



4. Agar strokes, 5 days. 



Beef agar: Moderate, flat, grayish white; old cultures become some- 

 what irridescent. 



Potato agar: Moderate, dirt}' yellowish white in 5 days; becomes 

 more yellowish with age. 



Peptone starch agar: Abundant, moist, grayish white in 5 days; be- 

 comes faintly yellowish in 10 days. 



5. Potato cylinder, 30 days : No growth. 



6. Gelatin stab: No growth after 30 days. 



7. Beef broth, 5 days : Heavily clouded. 



8. Litmus milk: No change in milk in 30 days. 



9. Plate cultures. 



Ammonia cellulose agar, 15 days. 



Form : Irregularly round. 



Size: 15 to 20 mm.; in 30 days the colonies frequentlj' reach a 

 diameter of 25 to 30 mm. 



Enzymic zone : When there are only a few colonies on the plate, 

 permitting rapid spreading, the clearing is all within the 

 colony until after 30 daj^s, when an enzymic zone usually de- 

 velops. On crowded plates the colonies always show an enzy- 

 mic zone of 1 mm. or more. 



Elevation : Slightly concave. 



Chromogenesis : Central portion of colony, usually 6 to 19 mm. 

 in diameter, is grayish white; outer portion of colony is vitre- 

 ous. The vitreous zone is usually surrounded by a thin white 

 rim. 



Internal structure : Colony is made up of medium-sized, loosely 

 arranged granules. 



Edge : Undulate. 

 Peptone cellulose agar, 15 days. 



Form : Round. 



Size : 2 to 3 mm. in 15 days ; 3 to 4 mm. in 25 days. 

 ' Enzymic zone: 1 to 1.5 mm. in 15 days; 2 to 3 mm. in 25 days. 



Elevation : Flat. 



Chromogenesis : Nucleus and rim are white, remainder of colony 

 semi-transparent grayish white. 



Internal structure : Granular. 



Edge : Entire. 

 Peptone starch agar, 5 days. 



Form : Irregularly round. 



Size : 3 to 4 mm. 



Enzymic zone : .5 to 1 mm. in 5 days ; 2 to 3 mm. in 10 days. 



Elevation : Convex. 



Consistency : Soft ; after 10 days colonies become brittle. 



Chromogenesis : Central portion of colony semi-transparent, 

 glistening white ; outer portion vitreous. 



Internal structure : Granular. 



Edge : Undulate. 



