122 CEOWN-GALL OF PLANTS. 



On March 7 there was no visible growth in any of the tubes which 

 had been in the thermostat. On March 9 the tube of bouillon 

 removed March 4 showed numerous white bacterial flocks but no 

 clouding. On March 14 typical strings appeared in the tube of 

 bouillon removed March 4, and later on a pellicle. No growth took 

 place in any of the other tubes. 



Conclusion. — No growth in +15 bouillon or agar at 37° to 37.5° C. 

 Exposure for 3 days retards subsequent growth at room tempera- 

 ture, and exposure for 4 days kills. 



TMs experiment was repeated in the same thermostat using htmus 

 milk, potato, slant peptonized beef agar ( + 16), and peptonized beef 

 bouillon ( + 15). It was begun March 7 at noon. The range of tem- 

 perature during the next 7 days was 37° to 37.4° C. Ten tubes 

 (4 milk, 4 potato, 1 agar, 1 bouillon) were held as checks at 19° to 

 22° C. Thirteen tubes (5 milk, 4 potato, 2 agar, and 2 bouillon) 

 were placed in the thermostat. All the checks showed distinct 

 growth at the end of 24 to 48 hours. At the end of 4 days there was 

 no visible growth in any of the tubes in the thermostat. On March 12 

 the 4 tubes of potato showed a trace of growth out of the water, i. e., 

 at the extreme top of each cylinder. The 5 tubes of litmus milk were 

 also now bluer than an uninoculated tube. 



On March 14 (end of 7 days), the litmus milk was bluer than on 

 March 12. There was still no visible growth either on the agar or 

 in the bouillon, and that on the potato cylinders was scanty and 

 restricted to the top. All the tubes were now removed to room 

 temperature and agar streaks were made from the litmus milk. 

 Two days later the agars streaked from the milk bore a good typical 

 growth. Growth in the htmus milk and on the potato increased at 

 room temperatures during the next week but no growth developed 

 in the bouillon or on the agar. 



Conclusion. — 37° C. is above the Umit for growth in +15 bouillon 

 and on agar, and close to the limit for milk and potato. Exposure on 

 agar or in bouillon for 7 days at 37° to 37.4° C. (mostly 37.1° to 

 37.3° C.) destroyed the organism. 



MINIMUM TEMPERATURE. 



Growth occurs at 0° C. Tests were made at temperatures varying 

 from + 10° to 0° C. with the result that growth was obtained even at 

 the lowest temperature in peptonized beef broth and on agar. The 

 ice box was used for temperatures above 3° C, and the records, made 

 night and morning, were continued for a period of 2 weeks, or less 

 if growth appeared earlier. 



For tests of growth at 0° C. the experiment was continued for 2 

 weeks in the following manner: Transfers were made from 3-day-old 

 agar cultures to agar and bouillon (2 tubes of each) which were cooled 



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