450 SOIL SCIENCE 



Bacillus desiduosus, n, sp. 

 Source: Soil from Covina, California, and Riverside, California. 



I. Morphology. 



1. Vegetative cells : Average dimensions 1 x .4 yu,- 



2. Endospores: None observed. 



3. Flagella : 1 to 3 in number ; 3 to 5 yu, in length. 



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



dyes. 



II. Cultural Characteristics. 



5. Agar strokes, 5 days. 



Beef agar: Scant, flat, grayish white, filiform growth. 

 Potato agar: Moderate, dry, cream-colored growth. 

 Peptone starch agar: Abundant, grayish white growth. 



6. Potato cylinder: No growth in 30 days. 



7. Gelatin stab: Moderate grayish white growth at surface and along 



track of needle, in 5 days ; no liquefaction in 30 days. 



8. Beef broth, 5 days : Lightly clouded. 



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



30 days. 

 10. Plate cultures. 



Ammonia cellulose agar, 15 days. 



Form : Irregularly round. 



Size: Surface colonies are small, rarely becoming more than 1.5 

 mm. in diameter; bottom colonies frequently attain a diameter 

 of 12 mm. 



Enzymic zone : 2 to 2.5 mm. in 15 days ; 3 to 3.5 mm. in 25 days. 



Elevation : Slightly convex. 



Chromogenesis : Colony is gray white with the exception of a 

 small white nucleus and a narrow white rim. 



Structure : Granular. 



Edge : Erose. 

 Peptone cellulose agar, 15 days. 



Form : Irregularly round. 



Size : Surface colonies 1 to 2 mm. ; bottom colonies may attain a 

 diameter of 25 mm. 



Enzymic zone : Surface colonies 1 to 2 mm. ; bottom colonies fre- 

 quently show no enzymic zone until after 20 days. 



Elevation : Slightly convex. 



Chromogenesis : Surface colonies are semi-transparent, yellowish 

 white. After 20 days' growth the surface and imbedded colo- 

 nies become quite yellowish; bottom colonies remain grayish 

 white. 



Internal structure : Granular. 



Edge : Lobate. 

 Peptone starch agar, 5 days. 



Form : Surface and bottom colonies are round or irregularly 

 round ; imbedded colonies are flaky. 



Size : 1.5 to 2.5 mm, 



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



Elevation : Flat. 



Chromogenesis : Grayish white ; some colonies show a small white 

 nucleus. 



