110 



to acid. After 8ome week.s, however, many of these cultures changed 

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

 acidity increased on concentration by Vjoiling rather than diminished. 

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

 acid is formed by this organism from a variety of substrata, but that 

 the formation of this acid is in no way associated with facultative 

 anaerobism or with the production of gas. 



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

 wa}' as Ps. liyoAimtM^ 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. 



FOKMATION OF AT.KALIES. 



Feebly acid or neutral culture media of various kinds were finally 

 rendered alkaline by 7^s-. /uj<icl)it]ii., but not rapidh' so, and all the tests 

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

 feeble alkali producer. This alkali is volatile, and a part of it, at least, 

 is undoubtedh" aimnonia. 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 jelh" 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 Avith methyl alcohol, milk with gh'cerin, hj^acinth 

 broth. 



The results obtained by special tests are givein under the following 

 heads : 



KosoLic Acid Test. 



The action of I*s. InjaclntJil on rosolic acid was tested in Diuihaurs 

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

 c. c. 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 (Witte's) 

 made this culture medium too red, and the fault was remedied b}' 

 adding to each 90 c. c. of the solution 6 drops of V 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: 



