112 INFECTIONS OF THE DIGESTIVE TRACT 



examination of the intestinal contents by means of this 

 stain is a real aid in forming a judgment as regards the 

 presence or absence of certain types of bacteria in the 

 digestive tract. 1 There are many conditions in which, 

 as must be obvious, it can be of little service. There 

 are instances in which Gram-stained microscopical fields 

 appear entirely normal, but after cultural and chemical 

 studies it is evident that abnormal decompositions are 

 at work and that pathological microorganisms are pres- 

 ent. On the other hand, one may often form an opin- 

 ion from the mere study of the fields as to whether the 

 bacteria present are capable of initiating putrefactive 

 processes or not. In order to make the staining of any 

 value it is necessary that the method should be carried 

 out in a uniform manner. The suspension of the flora 

 used should not be too concentrated, as the pictures may 

 be confused through an excessive number of bacteria. 

 Suspensions of fsecal material in the proportion of one 



1 In studying the bacteriology of the intestinal tract it is greatly 

 to be desired that very fresh specimens of the intestinal contents 

 be employed, since it may happen that certain delicate forms of 

 organisms may otherwise quickly die. In the case of colon bacilli, 

 of many coccal forms, and of most of the anaerobes a period of delay 

 appears to make little difference. In some of our investigations 

 we have worked with strictly fresh material, but it has necessarily 

 often happened that there was a delay of a few hours and some- 

 times of even greater time before cultures were made. The danger 

 in these cases is simply the danger of losing some types which 

 might otherwise be represented in the plates and fermentation 

 tubes. It is stated by some writers that B. bifidus is sensitive to 

 a depression of temperature, but we have not always found this 

 to be the case with the temperature of the ice box, since we have 

 been able to obtain growths of that organism in sugar bouillon 

 even after several days' residence of the material upon ice. 



