INFECTIONS OF THE DIGESTIVE TRACT 135 



these cases that the growth of what we may assume to 

 have been B. putrificus is no longer evident, and this 

 change in the character of the growths in the flasks has 

 corresponded to a clinical improvement in the condition of 

 the patients concerned. As regards B. aerogenes capsula- 

 tus, it cannot be said that we have learned more from the 

 seven-day flasks than from the fermentation tube sedi- 

 ments already mentioned. In a few instances it has 

 been observed that the peptone-bouillon flask has con- 

 tained enormous numbers of spores when the corre- 

 sponding calcium-carbonate flask has shown large num- 

 bers of vegetative forms of putrefactive microorganisms 

 and relatively few spores. Further studies are neces- 

 sary to determine the value of the seven-day-flask 

 method and to show how the bacterial fields are to be 

 interpreted. 



The chemical examination of the seven-day flasks 

 has included two different series of procedures. In the 

 case of the peptone-bouillon flask and the peptone- 

 bouillon flask containing calcium carbonate, the con- 

 tents have been examined with respect to hydrogen 

 sulphide, methyl mercaptan, volatile fatty acids, am- 

 monia, indol, skatol, and phenol. 1 Quantitative deter- 



1 A number of observations have been made upon the bouillon 

 and bouillon-carbonate flasks inoculated from the mixed flora 

 with a view to determining whether indol acetic acid is ever formed. 

 The method consisted in applying the three tests of Salkowski 

 to the material which remains behind after the distillation of 

 indol and skatol. In one case only has this residual material given 

 reactions with the three tests of Salkowski. This was in the case 

 of flasks prepared from a patient with peripheral neuritis and 

 pronounced psychosis resembling that of alcoholic intoxication. 



