30 



low at the end of a month (living-room temperatures of March and April) 

 and not at all sticky or gelatinous. Growth on this agar was retarded 

 a little at first, but b}^ the fifth day, when inoculated with large loops 

 from beef -broth cultures a week old and kept at 21^ to 23° C, there 

 was a good, dense, yellow streak. 



Fifteen months afterwards, a carefully preserved fiask containing 500 

 c. c. of this same agar -was opened and 100 c. c. of distilled water added 

 to make up for what had slowl}^ evaporated. The agar was then 

 steamed, filtered, and filled into clean test tubes, forming stock 307. It 

 was slightly browner and less elastic (more brittle) than when first made. 

 Duplicate streak and stab cultures of this organism and also of Ps. caiii- 

 pestris and Ps. phaseoli^ both of which formerly grew well upon this 

 agar, were made, using large loops of fluid cultures twelve daj^s old. 

 The loops were drawn lengthwise of the central part of the slant and 

 were easil}^ visible after the removal of the oese. Ps. jpliaseoli re- 

 fused to grow on this agar, either in streaks or stabs (4 tubes, 56 

 days). Ps. campestrls refused to grow in streak cultures and there 

 was no visible growth in the stab cultures until after the sixth day 

 (temperature 20° to 25°). This agar also exerted a powerful, restrain- 

 ing influence on Ps. hyacinthi. To the twelfth day the streak cultures 

 showed no growth (temperature 20° to 25° C). On the nineteenth day 

 one of the streak cultures showed a distinct growth, but it was onl}^ 

 1 or 2 mm. by 10 mm. and was mostl}^ in the agar. On the twenty- 

 sixth day the streak measured only 25 mm. by 3 to 5 mm. The streak 

 was dense, yellow, smooth, and wet-shining. The margins were thin 

 and well defined. The organisms had grown down into the agar. On 

 the fifty-sixth day the streak was 42 mm. by 5 to 8 mm. It was yel- 

 low, smooth, wet-shining, and contained several of the large X shaped 

 crystals. No growth ever appeared in the other streak culture. 

 Growth in the stab cultures was also much retarded and was very slow 

 to appear upon the surface. This agar was not retitrated, to deter- 

 mine its acidity, but it was acid to neutral litmus paper, or, at least, not 

 alkaline. When the moistened paper was dry, it seemed to be neutral. 



(2) The following agar made by Mr. P. H. Dorsett was also tried: 



1,000 c. c. of distilled water. 



10 grams of Witte's peptonum siccum. 



10 grams of agar. 



2.5 grams of Liebig's extract of meat. 



This fluid was cleared by the addition of the whites of 2 or 3 eggs 

 and rendered moderately alkaline to litmus by the addition of carbon- 

 ate of soda. It contained no muscle sugar and was H-15.5 of Fuller's 

 scale. 



Repeated tests were made on this agar, usually in the form of streak 

 cultures. There was no retardation of growth. The streak was dis- 

 tinct in 22 hours, at 27°, when the inoculation was made from a coconut 



