SOIL SCIENCE 



Consistency : Soft ; old colonies become somewhat gelatinous. 

 Chromogenesis : Small white nucleus, remainder semi-transparent 



grayish white. 

 Internal structure: Granular. 

 Edge : Entire. 

 Potato agar, 5 days. 



Form : Surface colonies, round ; bottom colonies, irregularly 



round. 

 Size : Surface colonies 1 to 1.5 mm. ; bottom colonies 2.5 to 4 nun. 

 Elevation : Convex. 

 Consistency : Soft. 



Chromogenesis : Grayish white, with a pearl-like luster. 

 Internal structure : Granular. 

 Edge : Entire. 



11. Filter paper broths, 15 days. The paper retains something of its origi- 



nal structure ; but shows many ragged holes where the fibers have 

 been dissolved away. Very slight agitation is sufficient to disinte- 

 grate the paper mass completely. The decomposition takes place 

 at about the same rate with ammonium sulphate or peptone as the 

 source of nitrogen. The decomposition was much slower when 

 casein or potassium nitrate was used. 

 III. Biochemical Features. 



12. Dunham's solution, 10 days. Ammonia produced ; nitrite produced. 



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



duced. 



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



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



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

 1.60; Maltose, 1.55; Glycerine, .45; Mannite, .20; Starch, 1.50. 



Bacterium castigatum, n. sp. 



Source : Soil from Banning, California ; Glendora, California ; and Wineville, 

 California. 



I. Morphology. 



1. Vegetative cells: Average dimensions 1.2 x .4 fi. 



2. Endospores : None observed. 



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



dyes. 



II. Cultural Characteristics. 



4. Agar strokes, 5 days. 



Beef agar: Abundant, moist, glistening, grayish white growth. 



Potato agar: Abundant, glistening, grayish white; becomes yellowish 



white after 10 days. 

 Peptone starch agar: Abundant, raised, somewhat rugose. 



5. Potato cylinders, 30 days : No growth. 



6. Gelatin stab: Moderate growth at surface and along track of needle 



in 6 days ; no liquefaction after 30 days. 



7. Beef broth, 5 days : Lightly clouded. 



8. Litmus milk: Reddened in 3 days; neither coagulated nor digested in 



30 days. 



