Micro-organisms of Maple Sap 545 



however, amounted to only a trace. After [9 days the papers 

 in CXV, CXL, CXLI, CXLII, CXUII, CXLVI, XVI, and 



L showed considerable blackening while those in LI, Ll\ and 

 XXXVI showed but a trace. Test papers in the controls re- 

 mained unchanged. 



Ammonia was produced by all strains, see pp. 542, 543. 



7. Reduction processes. — Litmus in litmus milk and in 

 litmus asrars was somewhat reduced by all strains. Nitrates 

 were reduced to nitrites by three strains. (See action on 

 nitrates, page 543). 



8. Odor. — A putrefactive odor was associated with de- 

 velopment on all the common media. 



9. Gas production. — None observed by the Smith fermen- 

 tation tube method in dextrose, lactose, sucrose, glycerin, or 

 nitrate broths. 



10. Crystals. — These were common in agar stab and plate 

 cultures, and in gelatin plate cultures. Twinned crystals of 

 magnesium ammonium phosphate were formed in Cohn's solu- 

 tion by strains LI and LIV. 



11. Oxygen requirements. — Agar stab cultures were ex- 

 posed to an atmosphere freed of oxygen by Buchner's pyrogal- 

 lic acid method (33). The tubes were placed in liter Novy 

 jars containing 10 grams of dry pyrogallic acid, to which 150 

 cc. of 1% sodium hydroxid solution was then added and the 

 jars immediately sealed. These were opened at the end of two 

 weeks incubation at room temperature. A barely visible sur- 

 face colony and a slight growth along the puncture was ap- 

 parent with all strains. The growth was limited and without 

 fluorescence. While this property was apparent 24 hours later, 

 its failure to develop in the oxygen free atmosphere might be 

 attributed to the limited metabolism rather than to the absence 

 of oxygen. Repeated trials yielded confirmatory results, but 

 other methods (pages 588 and 589) have shown the organisms 

 to be strictly aerobic. The slight growth obtained by the pyro 

 gallic acid method is attributed to the presence of small amounts 



