114 INFECTIONS OF THE DIGESTIVE TRACT 



present until this has been determined by cultural 

 methods. It may, however, aid one in forming conclu- 

 sions that are valuable on account of their high degree 

 of probability. In the case of a given individual, iso- 

 lation by careful plating and identification by suitable 

 methods of any dominant organism becomes a great aid 

 to subsequent interpretation of the Gram-stained field, 

 even though one may not have the opportunity to make 

 further isolations and identification in the same patient. 

 There are many applications of the Gram stain that 

 may advantageously be made in the study of intestinal 

 disorders, quite aside from the direct study of the faeces 

 and intestinal material obtained through the use of 

 cathartics. A study of the types of bacteria that are 

 dominant at different levels of the intestinal tract in 

 persons dying of various diseases is greatly facilitated by 

 the use of Gram staining. This method of study of the 

 bacteria at different levels has not yet received the at- 

 tention it deserves. I consider it especially important 

 to determine the distribution of the anaerobes in the 

 small intestine in numbers sufficiently great to enable 

 them to put their stamp on the character of the intestinal 

 decomposition. The Gram stain further has proved 

 highly useful in the study of the sediments in all the 

 fermentation tubes inoculated with the mixed faBcal 

 flora. Moreover, the same method has given consider- 

 able information in the study of the sediments obtained 

 in various media on which certain mixed flora have been 

 grown from seven to ten days. It is sometimes desira- 

 ble to make use of a staining method for spores in order 



