134 INFECTIONS OF THE DIGESTIVE TRACT 



putrefactive cleavages. Two objects have been served 

 through the employment of these flask cultures: first, 

 the study of the bacterial sediments after considerable 

 periods of growth; and, secondly, the study of the pro- 

 ducts formed on a representative medium. As regards 

 the characters of the organisms found in the sediments 

 (at the end of seven days) it is not possible at present to 

 state definitely to what extent the biochemistry of the 

 digestive tract can be furthered by the mere study of the 

 Gram-stained fields, without resort to cultural methods 

 permitting positive identification of the dominant forms. 

 The appearances in the flasks usually vary considerably 

 with the different media employed and also according 

 to the origin of the suspensions employed for inoculation. 

 It has been found, in general, that the anaerobes grow 

 more abundantly in the flasks in which a neutral re- 

 action is maintained, owing to the presence of calcium 

 carbonate. Whether the presence of calcium ions as 

 such influences the growth of the organisms in a specific 

 way is not known. It is certain that hi some cases of 

 excessive intestinal putrefaction attention has been 

 called to the prolific growth of certain anaerobes which 

 have been much less prominent in the intestinal con- 

 tents themselves and in the sediments of the fermenta- 

 tion tubes (in which the suspended bacteria have been 

 permitted to grow for a considerably shorter time than 

 in the flasks). In several instances microorganisms of 

 the morphological type of B. putrificus have been ex- 

 tremely abundant in the sediments of the calcium-car- 

 bonate flasks. Later it has been noticed in some of 



