Micro-organisms oi? Maple Sap 



381 



which the poured plate method was employed, but aliquots were 

 not used and no count of the number of recovered organisms 

 was obtained. 



The saps were mixed and titrated immediately before con- 

 centration, plates were poured to determine the character of 

 the infection, and a sample was removed and sterilized for the 

 purpose of the experiment previously mentioned. The sirups 

 were handled in all respects like those of the preceding year. 



series 10: sirups 89 to 96 



The sap for this series flowed on March 22 and was gathered 

 and given the first sterilization late in the afternoon of that day. 

 The second sterilization followed after an interval of 24 hours. 

 The samples were inoculated as soon as they were sufficiently 

 cool, and were incubated for y/ 2 days. The air temperature 

 maintained in the incubator is shown in the accompanying graph 

 (figure 11). 



Fig. 11. Graph of incubation temperatures for series 10; saps 89 to 90 in- 

 clusive. The arrow heads on next to the bottom line from left to right indi- 

 cate respectively the time of inoculation, the time of evaporation of the first 

 sample and the time of evaporation of the last sample. 



89. Number 89 was a control boiled down the day it was 

 obtained from the trees. The reaction was 1.2% N/100 acid. The 

 sirup contained 95.81% sucrose and 0.34^ invert sugar. The 

 color was 3, flavor 2, and score 900. 



90. Number 90 was inoculated with Bacillus aceris, a 

 stringy sap organism, strain CCXVII. A very deep milky type 

 of souring occurred and the material became quite stringy, 

 though it was by no means as ropy as unsterilized sap inoculated 

 with the same organism. An unpleasant yeasty odor was pro- 



