Micro-organisms of Maple Sap 



reaction in from [8 hours to 4 days. Two '. dextrose bouillon 

 in fermentation tubes, titrated hot with N 20 sodium hydroxid 

 against phenolphthalein showed acid production, considerably 

 more being present than in sugar tree bouillon. 1 See tables 

 qg } c^o, 51). Previous to boiling, the acid was masked by tin- 

 ammonia produced, the cultures became pink on addition of 

 phenolphthalein but decolorized on boiling, with increased 

 acidity. 



Lactose. — Litmus milk showed an alkaline reaction, becom- 

 ing doubtfully acid after several weeks. No acid, or a trace 

 in a few cases, was found by titrating 2 ( /i lactose bouillon. 

 (Tables 52, 53). By comparison most cultures in lactose bouil- 

 lon were found to produce no more acid than the control cul- 

 tures in sugar free bouillon. 



Sucrose — Same as lactose (table 54) 



Glycerin. — Acid production without gas formation was 

 observed with 11 strains on bouillon containing 50; of "Merck's 

 Blue Label" glycerin. (See tables 55, 56). 



The figures in the tables represent the percent of normal 

 acid or alkali produced in the respective media and were cal- 

 culated by subtracting the average reaction of duplicate con- 

 trols from the average reaction of duplicate cultures, or vice 

 versa. 



