230 BACTERIOLOGICAL EXAMINATION OF WATER. 



This table shows that seven cultures of B. coli were completely 

 agglutinated by the anti-typhoid serum, diluted 1-500 ; two 

 cultures were markedly agglutinated by the serum, diluted 

 1-1000, and one culture was completely agglutinated by the 

 serum in this dilution. This last culture was further tested at 

 once with the serum in still higher dilutions, and was found 

 to be completely agglutinated by the serum when diluted 

 1-2500. The serum was then tested with four cultures of B. 

 typhosus isolated from the spleens of the fatal cases which 

 furnished the stools under investigation. The results, together 

 with the effects of the serum on the two stock cultures, are 

 shown in the following table : 



TABLE B. 



It will be observed that all the specimens with the exception 

 of G x were completely agglutinated by the anti-typhoid serum 

 diluted 1500 ; with the higher dilutions, however, the results 

 varied, culture B. typhosus G and culture B. coli 62 were ob- 

 tained from the same case, and it will be noticed that the B. coli 

 was completely agglutinated by the anti-typhoid serum in a higher 

 dilution than was effective with the B. typhosus. If the serum 

 employed had been obtained from the patient it would have been 

 easy to explain the result by supposing that the patient suffered 

 from a mixed " typhoid" and "coli" infection. In the present case, 

 however, there could be no question of a secondary coli infection, 

 as the anti-typhoid serum was obtained by vaccinating a horse 

 with pure cultures of B. typhosus. It therefore appears that 

 coliform organisms in typhoid stools, as a result of their sur- 

 roundings, may become agglutinated by a highly dilute anti- 

 typhoid serum. That the sensibility to agglutination is only 



