Micro-organisms of Maple Sap 571 



Jt was heated to dissolve the salts, filtered and autoclaved. 

 Growth upon this medium occurred only with Ps. alba, Ps. longa, 

 and strain LI (also strain LIV identical with strain LI. c. E. page 

 550). After 20 days, transfers of those failing to develop were 

 made to broth and good typical growth resulted. The develop 

 ment of the three strains upon this medium was accompanied by 

 more or less blue-green to yellow-green fluorescence. Multiple 

 twinned crystals of magnesium ammonium phosphate formed 

 at the surface, which upon attaining sufficient size (about 1 cm. 

 in length), sank to the bottom where they were imbedded in a 

 viscid sediment. 



The medium was varied by substituting mono-potassium 

 phosphate for di-potassium phosphate without significant effect 

 upon the development. The character of the growth was the 

 same upon half strength Cohn's solution. 



Cultures developed a moderate clouding with white flaky 

 particles in suspension and a white, membranous pellicle hear- 

 ing crystals on the surface. More or less blue-green fluores- 

 cence appeared in the upper portions of the medium. Strain IJ 

 (LIV) and Ps. longa developed somewhat more slowly than Ps. 

 alba and often showed a scum rather than a membranous pellicle. 

 Typically twinned crystals were constantly associated with 

 development. Similar crystals were artificially formed by ex- 

 posing sterile tubes of Cohn's solution in a sealed jar with very 

 dilute ammonia. Liter flasks of Cohn's solution were inoculated 

 with strains LI and LIV and a sufficient quantity of the crystals 

 obtained for chemical analysis. The results showed that they 

 were magnesium ammonium phosphate due to the ammonia pro- 

 duced by the bacteria. 



12. Uschinsky solution (27:197). — The media were pre- 

 pared as follows : 



Distilled water 1 000. <•<•. 



Glycerin (Merck's Blue Label) 40. gr. 



Sodium chlorid ' • 



Calcium chlorid 1- 



Magnesium sulphate 0.4 



Di-potassium phosphate - 1 



Ammonium lactate 7. 



Sodium asparaginase 4. 



