Micro-organisms of Maple Sap 501 



portion of the medium. Cultures were grown al j<>. 25, and 30 

 C. and tested for nitrites at the cud of 3, 5, 10 and 25 days with 

 prompt and positive reaction. The test was made with the fol- 

 lowing solutions : 



(1) One gram of potato starch boiled in 100 cc. of distilled 

 water. (2) One-tenth gram of potassium iodid in 25 cc. of dis- 

 tilled water. (3) Two parts of chemically pure sulphuric acid 

 and one part water. To the tubes to be tested 1 cc. of number 1, 

 and 1 cc. of number 2, and, then, three drops of number 3 were 

 added, the tubes being agitated after each addition. 



Indol production. — The tests for indol production were made 

 in Dunham's peptone solution and in sugar free bouillon. Both 

 media were well suited to the growth of the organism. The test 

 was made by adding 10 drops of chemically pure sulphuric acid 

 (two parts sulphuric acid to one part water). After allowing the 

 tubes to stand for 20 minutes to determine the absence of reduc- 

 ing bodies, 1 cc. of 0.02% sodium nitrite solution was added. 

 Cultures 10 days old on Dunham's peptone solution gave a pink 

 color in from 1 to 5 minutes after the addition of the nitrite. 

 Cultures grown at 20 responded somewhat more slowly and with 

 a fainter reaction than those which w r ere held at higher tempera- 

 tures. As a check upon the work, tubes of the same medium 

 were inoculated with a strain of B. coli which produced indol 

 vigorously, and held at 30 C. Taking the color obtained from 

 these tubes as a standard, represented numerically by 10, cultures 

 of the organism held at 30 produced a color of 5 within one 

 minute. Cultures held at 20° produced a color of 1 after 15 or 

 20 minutes. A large number of cultures were tested in both 

 Dunham's solution and in sugar free bouillon and positive, though 

 sometimes faint, reaction was obtained in every case. 



Production of phenol. — Tests for the production of phenol 

 were made upon 50 cc. portions of 10 day old broth cultures of 

 the organism. The material was transferred to a distilling flask, 

 5 cc. of concentrated hydrochloric acid added, and about 20 cc. 

 of distillate collected. This was divided into three portions. 



