Report on the Bacteriology of Water. 489 



Thus in these uninfected L. Katrine waters only comparatively 

 slight multiplication took place, and at no time were there more than 

 a few colonies causing liquefaction of the gelatine. 



With these must now be compared the L. Katrine water infected 

 with typhoid, the results obtained with which are recorded in the 

 table (p. 488). 



These examinations show that although the water-bacteria present 

 in the unsterilised L. Katrine water must have undergone consider- 

 able multiplication, as shown by the great increase in the liquefying 

 colonies, yet this multiplication did not by any means keep pace 

 with the decrease in the number of typhoid bacilli ; for the total 

 number of colonies on the successive plates underwent continuous 

 decline. 



The actual proof of the persistence of the typhoid bacillus in these 

 waters had of course to be furnished by the method of phenol broth- 

 ^culture. Thus 



