Mayi5. I920 Halo-Blight of Oats 155 



Temperature; relations. — Thermal death point is between 47° and 

 48° C. 



Strain 36 usually gives a greenish tinge to bouillon cultures, which in 

 old cultures contrasts strongly with the brown of old "stock" cultures. 

 On ordinary beef-peptone agar the two strains can not be distinguished 

 but on potato-dextrose agar there is considerable difference in amount 

 of growth, and they are noticeably different in consistency. The most 

 important differences perhaps are in size and in nonformation of chains. 

 The rods of No. 36 are shorter and plumper. They seem to be two 

 strains of the same organism. 



III. — YELLOW organism 



Morphology. — The organism is a motile rod with rounded ends and 

 one to several polar flagella. It occurs singly or in short chains. When 

 grown for 24 hours on beef -peptone agar and stained by the Duck wall 

 modification of Pitfield method, it has an average measurement of 3.5 by 

 1.4 p., varying in length from 2.3 to 3.7 /i, and in width from 0.98 to 2.1 n. 

 No spores have been found. 



Beee-pEptone agar plates. — Colonies appear after 24 hours on 

 4- 10 beef-peptone agar; in 2 days they measure 2 mm. in diameter and 

 are a translucent light yellow. When a week old, surface colonies are 

 circular, 4 to 5 mm. in diameter, raised, smooth, lemon-yellow, with 

 entire translucent margins. Microscopically the internal structure is 

 finely granular. Deep colonies are lens-shaped and opaque. 



Beef-peptone agar stroke. — Growth in two days is moderate, fili- 

 form, flat, glistening, slightly contoured, translucent, light orange- 

 yellow, with a faint odor. Consistency is butyrous, and medium is 

 unchanged (PI. 30, B, c). The organism lives at least three or four 

 months on beef -peptone agar. 



Potato agar stroke. — In two days the growth is abundant, filiform, 

 flat, spreading, glistening, smooth, opaque, light orange- yellow. The 

 medium is unchanged, and the consistency butyrous. 



Gelatin stabs. — At 22° C. growth in -f 10 nutrient peptone gelatin is 

 moderate. The liquefaction at first is saccate along the stab and later 

 stratiform. Liquefaction is completed in 40 days. The surface growth 

 has a pinkish tinge, but the precipitate is yellow. 



Beef-peptone broth. — There is moderate clouding in -{-lo beef- 

 peptone broth in 24 hours at 25° C, very heavy clouding in 48 hours, 

 and a slight flocculent surface growth. In 3 days there is a heavy mem- 

 branous pellicle which breaks up when shaken and sinks to the bottom 

 of the tube. The precipitate is abundant and finely granular. Clearing 

 begins in about 2 weeks. 



Toleration of sodium chlorid. — Tables of neutral beef -peptone bouil- 

 lon containing respectively 2, 3, 4, 5, 6, and 7 per cent of sodium 

 chlorid were inoculated from potato agar slants. In 24 hours there was 

 164178°— 20 2 



