34 INFECTIONS OF THE DIGESTIVE TRACT 



ileocaecal valve, so that in the rectum the numbers of culti- 

 vable bacteria are very much less than in the ascending 

 colon. But although in the ascending colon we have usu- 

 ally the greatest numbers of bacteria, it should be noted 

 that their variety is often not so great as in the ileum. 



With a view to learning something about the anaerobic 

 conditions in the intestine, and their relation to the re- 

 ducing power of bacteria, a number of experiments were 

 made in which dogs were fed on meat containing methyl- 

 ene blue. 1 The animals were killed and the contents of 

 the intestine examined under boiled water in order to 

 determine at what point in the intestine reduction of 

 methylene blue had occurred. The following typical 

 result was obtained in one instance. A dog weighing 

 fourteen and one-half pounds had received methylene 

 blue in water, about two hundred milligrams in all. 

 On the third day he received one hundred milligrams 

 of methylene blue, placed inside a piece of cooked meat. 

 He ate heartily of this meat and four hours after the meal 

 the animal was killed and the intestine examined. 

 The following diagram of the large and small intestines 

 indicates the points at which the contents were examined. 



SMALL INTESTINE 



The stomach was found to be about one-half full, and 

 intensely blue. In the duodenum, at A, the intestinal 



1 1 am indebted to Dr. A. J. Wakeman for the series of proto- 

 cols on which these statements are based. 



