Mayi3. i9::o Halo-BHght of Oats 149 



ter, white, smooth, shining, round, with a denser center. When 1 1 days 

 old they are more or less irregularly circular, 5 to 10 mm. in diameter in 

 thin-sown plates, and flat with slightly raised margins. Microscopically, 

 with low powers, the internal structure is filamentous, the margin consist- 

 ing of folded parallel strands or chains. The margin is undulate. Deep 

 colonies are lens-shaped and opaque. The medium may be slightly 

 browned. The markings in Plate 31, A, B, E, F, are characteristic of 

 these colonies under a hand lens, and they do not disappear as the colonies 

 grow older. Very similar markings appear in young colonies of some of 

 the softrot organisms. A half dozen of these softrot organisms tried on 

 oats have not produced any halo lesions. 



(2) On plates of potato-dextrose agar the colonies grow more rapidly. 

 They are raised, v/hite, shining, opaque, with only slightly undulate or 

 entire margins, and of the same gelatinous consistency described above 

 (PI. 31, C; 32, A.) 



Gelatin colonies. — Growth slow, circular, crateriform, margins en- 

 tire to undulate with folded strands (PI. 31, G), liquefaction saucer-shaped, 

 rather slow. 



Gelatin stab. — Growth on -f 10 peptone gelatin at 22° C. is slow, best 

 at the top, with only a slight filiform growth along line of stab, liquefaction 

 crateriform. At the end of 2 days a small pit is formed at the surface 

 3 mm. deep. At the end of 6 days liquefaction extends two-thirds of the 

 way across a 20-mm. tube, and the pit is 10 mm. deep. At the end of 18 

 days liquefaction covers the surface to a depth of 14 mm. At the end 

 of 60 days (at 20°) the tube is only half liquefied. 



Potato cylinders. — At 25° C. there is moderate growth in 24 hours 

 and slight darkening of the medium. At the end of 4 days growth is 

 abundant, flat, smooth, glistening, butyrous to slimy, of a cream color, 

 and the medium is a uniform dark gray color. At the end of 20 days 

 there is a decided odor of decay. There is feeble diastasic action on 

 starch. 



Smith's potato starch jelly (5). — Growth moderate, diastasic action 

 feeble, medium stained a light bluish green. Traces of dextrin. 



Starch agar. — To melted tubes of +10 beef-peptone agar sterile 

 potato starch was added and plates poured. Tests with iodin showed 

 no diastasic action. 



TiTMUS sugar agars. — One per cent lactose, maltose, dextrose, sac- 

 charose, and galactose were used in beef-peptone litmus agar. Change of 

 medium to a bright red showed considerable acid production with dex- 

 trose and galactose; with saccharose there was less acid produced; and 

 with lactose and maltose there was no evidence of acid production. Re- 

 duction of litmus took place to a slight extent under the streaks with 

 dextrose and maltose. 



Milk. — In fresh isolations a soft curd forms in from 5 to 7 days, fol- 

 lowed by slow peptonization of the curd, which is completed in from 5 



