34 A SOFT EOT OF THE CALL A LILY. 



by the fact that when the cultures were removed from the incubator 

 at 42^ and kept at 20° C. g-rowth began within a few hours. If fresh 

 cultures were placed in the incubator at 43'^ C. life was not destroj^ed 

 within fifteen hours, but cultures removed at the end of twent3^-four 

 hours and placed under normal conditions failed to grow. If the 

 temperature was kept constants above 41° C. no growth appeared in 

 any of the media used. Hence after man}' repeated tests it was 

 decided that 41° C. is the maximum temj^erature at w^hich this organism 

 will grow. 



MIXIMUIM TEMPERATURE. 



To determine the lowest temperature at which the calla-rot organ- 

 ism will grow, fresh cultures were placed in the ice box at different 

 elevations, with as little variation as possible in the quantity of ice, 

 so that the temperature remained fairly constant for each set of cul- 

 tures, but varied for the different sets from about 3° to 9° C. Set 1 

 consisted of cultures of beef broth, Uschinsky's solution, gelatin stab 

 cultures, and slant agar, and was kept at a temperature between 3° 

 and 5° C. for twenty-four days. The control cultures at room tem- 

 peratures of 20° C. produced growth as usual within twenty-four 

 hours, while the cultures at the low temperature showed no signs of 

 growth until the}' were removed from the ice box at the expiration 

 of twenty -four days, when all produced growth within twenty-four 

 hours. Set 2 was kept at approximately 0° C. for nine days, at the 

 end of which time growth appeared, slightly clouding the beef broth. 

 The temperature sometimes fell to 5° C, but did not at any time dur- 

 ing the nine days exceed 6i° C. Set 3 was kept at approximately 9° 0. 

 Slight growth beg-an in from two to four davs. Beef broth was the 

 first to show the growth in the low temperatures, while in the high 

 temperatures it was usually the Uschinsky solution that clouded first. 

 Six and one-half degrees centigrade seems to be the lowest tempera- 

 ture at which growth will take place. At 9° C. growth takes place 

 slowly and the colonies in agar-plate cultures at this temperature are 

 small and round, as was found to be the case in the high temperatures. 



OPTIMUM TEMPERATURE. 



The calla-rot organism grows readilv between 15° and 37° C. 

 Fresh cultures of beef broth, Uschinsky's solution, and agar inoculated 

 with a 1 mm. loop of a 24-bour-old beef-broth culture, placed in an 

 incubator at 37.5° C, showed signs of growth within six hours. Simi- 

 lar cultures at 35° C. showed a distinct growth in four hours. As it 

 is sometimes difficult to compare culture solutions accurately with ref- 

 erence to the intensity of clouding, agar-plate cultures were also used. 

 The fresh cultures were placed at different temperatures — some at 20°, 

 some at 30°, some at 33°, some at 35°, and some at 37.5° C. In 

 fifteen hours the plates at 35° C. showed the colonies most distinctly. 



