'TYPHOID FEVER 69 



finds its way into some place where it has no business. Normal feces 

 contain colon bacilli in great numbers. 



When the typhoid bacillus finds its way into man's intestinal tract 

 it is likely to develop typhoid fever. The stool of the typhoid victim 

 is laden with the Bacillus typhosus. Between the extremes of the 

 typho-colon group, there are two varieties of the B. typhosus, Para- 

 typhus A and B, B. enteritidis, mouse typhoid, dysentery bacilli and B. 

 fecalis alcaligenes. A typical typhoid bacillus is highly motile; it 

 does not coagulate milk ; it does not redden litmus milk ; it forms blue 

 colonies on plates of gelatine colored with litmus; when grown in 

 whey colored with litmus it produces only a slight cloudiness and at 

 most only slightly reddens the medium; when grown in fermentation 

 tubes in a solution containing grape sugar it develops no gas; when 

 grown in agar colored with neutral red it does not change the color 

 or develop any gas; when grown in peptone solutions or bouillon it 

 does not develop indol. A typical colon bacillus is non-motile ; it does 

 coagulate milk ; it reddens litmus milk ; it forms red colonies on plates 

 of gelatine colored with litmus; when grown in whey colored with 

 litmus, it produces a marked cloudiness and deeply reddens the 

 medium; when grown in fermentation tubes in solutions of grape 

 sugar, it develops gas abundantly; when grown in agar colored with 

 neutral red it does develop gas and changes the color; when grown 

 in peptone solution or bouillon it develops indol. It will be seen from 

 these facts that it is easy to distinguish between a typical typhoid and 

 a typical colon bacillus, but there are varieties of each which may 

 contradict any one of these statements, while the intermediate organ- 

 isms differ from one another and in their own varieties. It follows 

 that only an expert in this line is fitted to locate exactly the members 

 of this large group of organisms. However, with proper training one 

 becomes quite expert and the identification of typhoid bacilli in the 

 stools and urine of suspected cases becomes less difficult than one 

 would suppose from the above statements. 



The recognition of this organism in drinking water remains so diffi- 

 cult in spite of all the work that has been done that it is seldom 

 attempted and the fitness of a water for drinking purposes is deter- 

 mined by the number of colon bacilli in a given volume of the water. 

 This is easily done by counting the number of red colonies which 



