170 



SEVENTH REPORT. 



Solutions of the substance give tlie pine slij) reaction, evidence of the 

 presence of the indol nucleus in the original molecule. 



The constitution of tryptophan, as determined by the original workers 

 Avith the substance is skatol-amido-acetic acid. 



In our own work, in the first series of bacterial cultures, four different 

 media were used, viz.: sugar-free bouillon, sugar-free bouillon having 

 added to it one-tenth gram of tryptophan per one hundred c.cm. Dun- 

 ham's solution, as ordinarily prepared, and. Dunham's solution plus 

 trypto])han in the same i)roportiona! amount a's the beef-tea received. 

 The media, after sterilization, were inoculated from the laboratorv stock 

 cultures and incubated at 30° C. 



The indol test used was ten drops of a one-hundredth per cent, solu- 

 tion of sodium nitrite, and six drops of sulphuric acid. s|>. gr. 1.84, added 

 lo one c.cm. of the cultures. The results of twenty-four liours incubation 

 are shown in Table I, the amount of indol being expressed in grams per 

 c.cm. of the cultures. 



TABLE I. 



■Comparative amounts of indol produced in media as ordinarily prepared, and media having 

 tryptophan added. Indol in grams per c. cm. of the culture. 



Organism. 



B. acidi laetici 



B. proteus vulgaris 



B. fluorescens putidus 



Bact. zoi)fii 



B. ruber of Kiel 



B. butyricus 



B. rubidus 



Sarcina aurantiaca 



B. prodigiosus 



B. violaceus 



B. cyanogenes 



B. mesentericus vulgatus 



B. subtilis 



B. megaterium 



Sarcina lutea 



B. typhosus 



B. coli communis 



v. Finkler-Prior 



B. pyocyaneus 



B. anthracis 



V. cliolerae Asiaticae 



Diplococus pneumoniae 



B. Metchnikovi 



B. cliolerae sui? 



B. cholerae gallinarum 



B. icteroides 



.Staphylococcus pyogenes aureus 



B diphtheriae 



B. mallei 



B. pneumoniae (Friedlander) . . . 



M. tetragenus 



B. dysenteriae 



'Control 



Dunham's 

 s )lution. 



Trace. 

 0.00015 

 None. 

 None. 

 None. 

 None. 

 None. 

 None. 

 None. 

 None. 

 None. 

 None. 

 None. 

 None. 

 None. 

 None. 

 0.0001 

 0.0001 

 None. 

 None. 

 0.0001 

 None. 

 Trace. 

 None. 

 None. 

 None. 

 None. 

 None. 

 None. 

 None. 

 None. 

 None. 

 None. 



Dunham's 



solution 



plus 



tryjituphan. 



0.0001 



0.0004 



0.0003 



0.0001 



0.0001 



0.0003 



0.0002 



Trace. 



0.0001 



None. 



None. 



None. 



None. 



None. 



None. 



None. 



0.0003 



0.0002 



Trace. 



None. 



0.001 



Trace. 



0.0001 



0.0001 



Trace. 



None- 



None. 



None. 



None. 



None. 



N(me. 



None. 



None. 



Sugar-free 

 bouillon. 



0.0001 

 0.0001 

 Trace. 



None. 

 None. 

 None. 

 None. 

 None. 

 None. 

 None. 

 None. 

 None. 

 None. 

 None. 

 None. 

 None. 

 Trace. 

 None 

 None. 

 None. 

 0.0004 

 None. 

 Trace. 

 None. 

 None. 

 None. 

 None. 

 None. 

 None. 

 None. 

 None. 

 None. 

 None. 



Sugar-free 



bouillon 



plus 



tryptophan 



0.0001 

 0.0002 

 0.0001 



Trace. 

 Trace. 

 Trace. 

 Trace. 

 None. 

 0.0001 

 None. 

 None 

 None. 

 None. 

 None. 

 None. 

 None. 

 0002 

 0.0002 

 None. 

 None. 

 0.0008 

 Trace. 

 0.0001 

 0.00015 

 Trace. 

 None. 

 None. 

 None. 

 None. 

 None. 

 None. 

 None. 

 None. 



Thus out of thirty-two organisms, nine non-pathogenic and eight patho- 

 genic organisms showed indol production, and in every case the cultures 

 in Dunham's solution plus tryptophan showed more indol than the cul- 

 tures in ordinary Dunham's solution ; and of the same cultures in sugar- 

 free bouillon Avith. and without tryptoi)han respectively, all gave similar 



