ISOLATION OF SPECIFIC PATHOGEXES 81 



typhoid bacilli from stools. In a personal letter he 

 says: ''If stools are inoculated into brilHant green broth 

 (extract broth neutral to phenolphthalein with i per 

 cent of glucose), there is a suppression or inhibition 

 of many of the lactose fermenters. The dye, even in 

 strong solutions, has little effect on the growth of 

 pyocyaneus, proteus, paratyphoid-like (intermediates), 

 and aerogenes (mucosus types, non dulci: fermenters) 

 bacilli. T^-phoid bacilli will multiply in dilutions of 

 the dye that inhibit the colon tj^^es. As the faeces 

 itself reduces the actixdty of the dye, adjustment is 

 necessary and can be obtained by inoculation of o.i 

 c.c. of the faecal suspension into broth containing 

 1-300,000, 1-400,000 and 1-500,000 of the dye. These 

 tubes, after 15 to 18 hours' incubation, are plated 

 on Endo." 



Concentration by Agglutination or Precipitation. A 

 physical concentration of the t}phoid bacilU precedes 

 enrichment or isolation in the procedure recommended 

 by many authors. Klein, as noted above, accomplished 

 this by passing the water through a Berkefeld filter. 

 Other workers have made use of agglutination or chem- 

 ical precipitation for the same purpose. 



The phenomenon of agglutination was made the 

 basis of a method of isolating B. t}'phi from water by 

 Adami and Chopin (Adami and Chopin, 1904). Two- 

 liter samples of the water were collected in sterilized 

 bottles (Winchester quarts), and to each was added 

 20 c.c. of I per cent glucose broth. The sample was 

 incubated for 18 to 24 hours at 37° C, after which 



