110 



to acid. After some weeks, however, main' of these cultures changed 

 from alkaline to neutral, and others became decidedly acid, and the 

 acidity increased on concentration by boiling* rather than diminished. 

 It would seem, therefore, that a small quantity of some non-yolatile 

 acid is formed by this organism from a yariet}' of substrata, but that 

 the formation of this acid is in no wa}" associated with facultative 

 anaerobism or with the production of gas. 



The other yellow organisms, so far as tested, behaved in the same 

 wa3' as Ps. kyacintJii^ so far as relates to the slow development of a 

 non-volatile acid in the presence of certain sugars and of certain vege- 

 table substances rich in sugars. 



FORMATION OF ALKALIES. 



Feebly acid or neutral cultui-e media of various kinds were finally 

 rendered alkaline by Ps. hyacinthi^ but not rapidly so, and all the tests 

 instituted lead me to the conclusion that this organism is a relatively 

 feeble alkali producer. This alkali is A^olatile, and a part of it, at least, 

 is undoubtedly ammonia. Neutral or acid reactions were observed in 

 the following old and very old cultures: Carrot, sugar beet, sweet 

 potato, 3^ellow globe turnip, grape sugar agar, cane sugar agar, nutrient 

 starch jell}" with cane sugar, nutrient starch jelly with glycerin. The 

 following culture media became and remained alkaline: Potato, coco- 

 nut, ordinary nutrient agar, salted peptone water, milk, milk with 

 grape sugar, milk with methyl alcohol, milk with glj^cerin, hyacinth 

 broth. 



The results obtained by special tests are giA^en under the following 

 heads : 



RosoLic Acid Test. 



The action of Ps. hyacinthi on rosolic acid was tested in Dunham's 

 solution. To each 100 c. c. of this salted peptone water was added 1 

 CO. of a solution made of 0.5 gram rosolic acid; 20 c. c. distilled 

 water; 80 c. c. absolute alcohol. The alkali in the peptone (\Yitte's) 

 made this culture medium too red, and the fault was remedied by 

 adding to each 90 c. c. of the solution 6 drops of j^ HCl, which ren- 

 dered the medium yellowish and suitable for the experiment. The 

 results obtained with this organism and with others used for compari- 

 son are given in the following table: 



