1922] 



ROSEN — A BACTERIAL DISEASE OF FOXTAIL 363 



Gelatin plates. — On poured plates, kept at about 20° C, test- 

 ing P H 6, colonies appeared slowly. In 48 hours they were barely 

 visible, being in the form of fine white points. By the fifth day 

 well-separated surface colonies measured 1.5 to 2.5 mm. in diam- 

 eter; they were round, the margin was entire, appearing coarsely 

 granular when viewed with the low power of a microscope; the 

 granules were not arranged in any definite pattern but were some- 

 what larger toward the middle of the colony. The color was glis- 

 tening white with a bluish lustre towards the margin and a yel- 

 lowish tinge in the middle. There was no liquefaction and no 

 odor. In contrast to surface colonies, which possess even mar- 

 gins, colonies which were imbedded presented uneven margins, 

 and were often deeply lobed. These colonies appeared very rough 

 under the microscope, and the granules were much larger than 

 those of surface colonies. Imbedded colonies were also much 

 reduced in size. On P H 7 gelatin plates the growth was the same 

 as on P H 6 gelatin. As the colonies advanced in age the granula- 

 tion so evident up to the fifth day gradually disappeared. When 

 plates were kept at 25° C, a temperature which caused a slight 

 softening of gelatin testing Ph 6-7, the growth was noticeably 

 better, well-scattered colonies measuring 5 to 6 mm. on the 

 seventh day ; as the gelatin softened the surface colonies sank into 

 the medium and took on concentric striae, a character not evi- 

 dent on firm media. Even after 2 months there was no liquefac- 



tion. 



and 



P 



refused 



gel when it has been rendered alkaline before sterilization). On 

 gelatin growth as a whole was not as good as on agar but it should 

 be noted that this might be due to the comparatively low tem- 

 perature at which gelatin is kept, the organism being one which 

 grows best at a comparatively high temperature. No colorless 

 zone with white precipitate has been noted on gelatin. 



Gelatin stabs. — Growth was visible only in the upper part of 

 the stab. There was no liquefaction. 



Plain gelatin stabs. — As there is a possibility that the pep- 

 tone and beef extract of nutrient gelatin may interfere with 

 the enzymes which liquefy gelatin, stabs were made in a medium 

 containing no nutrients except the 1.5 per cent gelatin. On these 

 the growth was but slight and in the upper part of the stab. Here 

 also there was no liquefaction. 



