426 BACTERIOLOGY. 



ployed ; and this corresponds with the results of a fairly 

 wide personal experience with the test. 



In the light of present experience it is fair presump- 

 tive evidence that the serum is from a case of typhoid 

 fever when unmistakable agglutination and cessation of 

 motion are seen in from fifteen to twenty minutes after 

 typhoid bacilli are mixed with the serum of a conspicu- 

 ous febrile condition. 



The blood of certain animals, as well as a number of 

 chemical substances, such as corrosive sublimate, alco- 

 hol, salicylic acid, resorcin, and safranin in high dilution, 

 cause agglutination of the typhoid bacilli ; but the reac- 

 tion is not specific, for in most cases they have the same 

 effect on other motile bacilli. 



DRINKING WATER. All the points with regard to 

 morphologic and biologic characters of bacillus typho- 

 sus, and of the organisms closely resembling it, should 

 be borne in mind in the examination of drinking-water 

 supposed to be contaminated by typhoid dejections, for 

 the organisms which most closely approach the typhoid 

 bacillus in growth and morphology are just those organ- 

 isms which would appear in water contaminated from 

 cesspools i. e., the organisms constantly found in the 

 normal intestinal tract. Even in the stools of typhoid- 

 fever patients the presence of these normal inhabitants 

 of the intestinal tract renders the isolation of the typhoid 

 organisms somewhat troublesome. 



METHODS OF ISOLATING THE TYPHOID BACILLUS. 

 From the foregoing it is obvious that bacillus typhosus 

 is so variable in many of its biological peculiarities, and 

 is so closely simulated in certain respects by a group of 

 other organisms to which it appears to be botanically 



