12 TRANSFORMATION OF THE INTESTINAL FLORA 



These suspensions were diluted to match tube eight of the McFarland 

 (1907) nephelometer scale. The methods of bacteriological examina- 

 tion of fecal specimens are given at some length in the special chapter 

 on methods (pages 114-117) which goes into the preparation and use 

 of whey agar plates, Veillon tubes and Gram-stained miscroscopic slides. 

 The amount of gas formation and the relative numbers of B. acidoph- 

 ilus colonies in the Veillon tubes are recorded by the following system : 



Special tests for B. welchii were at times made by the milk culture 

 and heat test, but these were regarded unnecessary as a routine pro- 

 cedure, since the Veillon tubes provide the right conditions for develop- 

 ment of this organism. 



In selecting methods for the bacteriological examination of intestinal 

 contents and fecal specimens the aim has been to employ simple and yet 

 sufficiently reliable procedures to obtain a general insight into the num- 

 bers and biological activities of important groups of bacteria which are 

 capable of establishing themselves in the intestinal tract, and to make 

 it possible to correlate particular types of organisms with specific 

 dietary conditions. The methods chosen enable one to gain a clear view 

 of the relative predominance and activities of the fermentative and 

 so-called putrefactive bacteria, both aerobic and anaerobic. 



During the investigation pure stock cultures have been grown in 

 either whey broth, whey agar, or in milk. The hydrogen ion concen- 

 tration of the broth and agar, unless otherwise noted, was adjusted 

 to pH 6.8. Whey agar has been found to be of particular value for 

 preserving the different strains of B. acidophilus and B. hulgaricu^, 

 transplants being made onto the entire slope of the agar with a liberal 

 amount of the inoculum. 



Samples of intestinal contents were procured in the following manner. 

 After a fast of twenty-four hours the rats were killed with chloroform, 

 the abdominal cavity opened and the entire intestinal tract spread out 

 on a sheet of paper. The various sections of the intestine, namely the 

 duodenum, jejunum, ileum, caecum and the colon and rectum, were then 

 removed with shears. The contents of each section were forced out by 

 a process of stripping with forceps into test tubes containing sterile 

 physiological saline solution and broken glass. Standard emulsions 

 were prepared and subjected to precisely the same bacteriological 

 examinations as the samples of feces. 



