MICHIGAN ACADEMY OF SCIENCE. 



171 



results Avitli the exception of the hietie acid bacillus, which gave an 

 equal amount in both. 



The organisms Avere next cultivated in proteid-free media. Uschinsky's 

 medium was prepared, a portion being tubed plain, and another portion 

 receiving one-tenth gram of tryptophan per one hundred c.cm. of solu- 

 tion. Cultures in these two media were incubated at 30° C. for 24 hours, 

 when indol tests were made with the results shown in Table II. 



TABLE II. 



Comparative amounts af indol produced in twenty-jour hours in Uschinsky's medium with, 

 and without tryptophan added. Indol in grams per c. cm. of the cultures. 



Organism. 



B. acidi lactici. 



B. proteus vulgaris 



B. fluorescens putidus 



Bact zopfii 



B. ruber of Kiel 



B. butyricus 



B. rubidus 



Sarcina aurantiaca 



B. prodigiosiLs 



B. violaceus 



B. cyanogen es 



B. mesentericus vulgatus 



B. subtilis 



B. megaterium 



Sarcina lutea 



B. typhosus 



B. coli communis 



v. Finkler-Prior 



B. pyocyaneus 



B. antliracis 



V. cholearae Asiaticae , 



Diplococcus Fraenkel 



V. Metchnikovi 



B. cholerae suis 



B. cholerae gallinarum 



B. icteroides 



Sta])hylococcus pyogenes aureus 



B. diphtheriae 



B. mallei 



B. pneumoniae (Friedlander) . . . 



M. tetragenus 



B. dysenteriae 



Control 



Uschinsky's 

 medium. 



None. 

 None. 

 None. 

 None. 

 None. 

 None. 

 None. 

 None 

 None 

 None. 

 None. 

 None. 

 None. 

 None. 

 None. 

 None 

 None. 

 None. 

 None. 

 None 

 None. 

 None. 

 None. 

 None. 

 None. 

 None. 

 None. 

 None. 

 None. 

 None. 

 None. 

 None. 

 None. 



Uschinsky's 



medium 



plus 



tryptophan . 



0.0002 

 0.0004 

 Trace. 

 0.0001 



None 

 None. 

 None. 

 None. 

 None. 

 None 

 None. 

 None 

 None. 

 None. 

 Trace. 

 None. 

 0.0002 

 0.0002 

 0.0001 

 None. 

 0.0001 

 0.0001 

 0.0002 

 None. 

 None. 

 None. 

 None. 

 None. 

 None 

 None. 

 None. 

 None. 

 None. 



Here again the results shown in the table give positive evidence that 

 the tryptophan is the source of the indol. 



The next step was to prepare some medium in which this principle 

 might be utilized without resorting to the long process of isolation of 

 the purified try])tophan. A ])ortion of casein was digested with trypsin 

 "until a strong glyoxylic reaction could be obtained, when the fermenting 

 mixture was heated and filtered, yielding a clear, dark amber solution. 

 A portion of this solution was tubed directly and sterilized, while 

 another portion was used as the basis of a modified Uschinsky solution 

 of the following composition : 



Sodium chloride 5 grams. 



Dipotassium phosphate 2 " 



Ammonium lactate 6 " 



Asparaginic acid 3 " 



Casein try])to])han solution 1000 c.cm 



