CHARACTERS OF GALL ORGANISMS FROM OTHER SOURCES. 147 



Table IX. — Showing indol reaction of crown-gall organisms " in two media at room 



temperature. 



a Tested by adding to each tube 1 c. c. of 1 :200 sodium nitrite and 10 drops of sulphuric acid. 

 f> Positive reaction only after heating to 80° C, except daisy and trace in peach and Flats poplar, 

 c No growth. 



Owing to Brizi's statements respecting the rapid production of 

 indol by his Bacillus pojyuli additional tests for indol were made in 

 river water containing 2 per cent Witte's peptone, using Flats poplar, 

 the virulence of which had been recently established: 



(1) Tube copiously inoculated and incubated 24 hours at 30° C, 

 which gave an unusually heavy growth. Result: No trace of color 

 on adding reagents, and none, or merest trace, on heating for five 

 minutes at 80° C. 



(2) On July 26, 1910, the above experiment was repeated. Sev- 

 eral tubes were inoculated copiously and incubated at 30° C, the 

 growth being prompt and typical. They were tested as follows, 

 using for each tube 1 c. c. of sodium nitrite water (i : 200) and 10 

 drops of sulphuric acid. 



July 27 (28 hours) : Considerable growth but no trace of red color 

 at first, nor after some minutes, nor on heating at 80° C. for 4 minutes. 



July 28 (50 hours): Growth has increased. No trace of red color 

 cold, and none on heating for 5 minutes at 80° C. 



July 29 (74 hours): Good growth continues. No red color on 

 adding reagents cold. A trace (?) on heating at 80° C. 



213 



