116 CROWN-GALL OF PLANTS. 



the clouded part was distinctly separated from the clear part as if by 

 a veil. The glycerin solution contained a fuie white cloudiness 

 different in appearance from any of the other fluids.'* At the end of 

 14 days the clouding had extended up the closed end of the tube, 

 about In cm., in the solution containing dextrose and that con- 

 taining cane sugar. Eighteen days after inoculation the tubes were 

 tested with neutral litmus paper. In the tubes containing glycerin, 

 mannit, and lactose the paper turned blue and in the dextrose and 

 cane-sugar solutions it turned slightly red. In the tubes containing 

 maltose there was no change in the sensitized paper.^ No gas formed 

 in any of the tubes, nor were any of them clouded throughout the 

 whole of the closed end. All the control tubes remained sterile. 



AMMONIA PRODUCTION. 



Moderate to strong. 



NITRATES. 



Nitrates are not reduced. Five tubes each containing 10 c. c. 

 peptonized beef broth to which had been added just enough nitrate 

 of potash to make 1 per cent nitrate-bouillon solution were inoculated 

 with the daisy organism. At the end of four days the tubes were 

 distinctly clouded and tests were made for nitrites as follows: To 10 

 c. c. of the nitrate bouillon containing the grooving organism 1 o. c. of 

 boiled starch water and 1 c. c. of potassium-iodid solution (1:200) 

 were added. A few drops of strong sulphuric-acid water (2:1) were 

 then added, but no trace of a blue color resulted, indicating that no 

 nitrites had formed. This experiment was repeated several times at 

 long intervals with subcultures from various isolations, but always 

 with the same result. (See p. 148.) 



INDOL. 



Indol is irroduced in small quantity and very slowly. In 1908 several 

 tubes of Uschinsky's solution with 1 per cent Witte's peptone added 

 were inoculated with fresh agar cultures of tlie daisy organism. The 

 inoculated tubes showed marked growth in four days and a test was 

 made for indol, using concentrated sulphuric acid, and dilute sodium 

 nitrite (1 :200 in water). This test showed no trace of indol, even 

 upon beating to 80° C. after the sulphuric acid and nitrite were added. 

 This tost was repeated at the end of 10 days, but again witli negative 



a Wc were not able to duplicate this in subsequent cultures and now think it, may have been due to 

 precipilation of some of the peptone on standing. 



b This experiment was repealed two years later with practically the same result — the neutral litmus 

 paper showing only the barest trace of alkalinity after the cultures were 10 days old. After three months 

 the fluid was clear, or nearly so, until shaken. There wa3 enough v.hite precipitate to make the unstained 

 fluid flocculent filamentous turbid on shaking. It was still neutral to Utmus paper. 



213 



