176 BACTERIOLOGICAL EXAMINATION OF WATER. 



tested in Wright's laboratary at Netley, did not bear out Rollers 

 and Gruber's contention. 



Culture G. of B. typhosus, which was not agglutinated by 

 the anti-typhoid serum, when diluted above 1-500, possessed 

 little or no virulence as compared with culture 13 p, which was 

 markedly agglutinated by the serum diluted 1-10,000. Culture 

 G x which was isolated from the spleen of a typhoid patient, 

 at first proved highly resistant to the action of the anti-typhoid 

 serum, but after being preserved in milk for six months it re- 

 acted to the serum diluted 1-1000, and yet with this diminished 

 resistance to the anti-typhoid serum there appeared to be no 

 diminution in its virulence. Consequently it appears that there 

 is no constant relation between the virulence of the B. typhosus 

 and its reaction to anti-typhoid serum. 



All my cultures, with the exception of G x , were completely 

 agglutinated by anti-typhoid serum diluted 1-500, and this I 

 should propose as a working limit, as it would exclude all forms 

 of Coli isolated from normal stools. At the same time the 

 existence of such cultures as G x shows that it is impossible to 

 lay down a hard and fast rule. This culture was carefully 

 worked out and compared with other undoubted cultures of 

 B. typhosus before it was finally accepted as a true B. typhosus. 

 The results of the various tests are shown in the table on 

 page 232, from which it appears that G x responds to all the 

 cultural reactions considered typical of B. typhosus. Cultures 

 of this nature are probably rare, as I have only met with this 

 one during several years' work at the subject. 



Sacquepee has described " Eberthiform " bacilli, which, when 

 isolated from water, typhoid stools, and also from the spleens of 

 fatal cases of typhoid fever, did not appear susceptible to agglu- 

 tination by anti-typhoid sera. The Eberthiform bacilli also 

 differed from the true B. typhosus by producing a brownish 

 growth on potato. When these bacilli were preserved in closed 

 tubes, without access of light or air, they were gradually trans- 

 formed into typical typhoid bacilli, producing a colourless 

 growth on potato and reacting readily to anti-typhoid sera. 

 The time required for this transformation varied between 

 six and ten months, and the susceptibility to agglutination 

 appeared to be gradually acquired during this period. The 



