414 Profs. Percy Fraukland and Marshall Ward. 



The sample of Thames water which between the date of collection 

 (4.5.1893) and the date of first examination (11.5.1893) had remained 

 in bottles almost completely filled up to the stopper, and at a tempera- 

 ture of about 10 12 C. exhibited in the first instance an unusually 

 small number of bacteria (only 290 in 1 c.c.). There can be little 

 doubt that the original number present must have been greater than 

 this, and have become diminished during this period of residence in 

 the stoppered bottles, for on introduction into the flasks plugged with 

 cotton-wool they underwent enormous multiplication. In the flask 

 kept at 19 C. the multiplication was doubtless most rapid, but had 

 already fallen again to 45,000 per c.c. on the second examination, 

 whilst in the flask kept at 6 C. multiplication and subsequent decline 

 were probably both less rapid, so that on the occasion of the second 

 examination the number present was still 563,000 per c.c., which 

 underwent continuous diminution during the remainder of the time 

 that this flask was kept under observation. 



These phenomena of initial multiplication followed by decline have 

 been already frequently called attention to, both in the former 

 Reports and by other observers, so that there is no necessity to dwell 

 further upon it here beyond pointing out that it shows that the 

 water- bacteria in this sample of water employed were in an active 

 and flourishing state under the conditions maintained during the 

 experiment. 



Examination by Plate-Cultivation of the Unsterilised Thames Water 

 infected with Typhoid and B. coli communis respectively. 



Having in the previous pages traced the numerical changes which 

 took place in the bacterial contents of the control uninfected un- 

 sterilised Thames water, I will now proceed to describe what occurred 

 in the case of the same unsterilised Thames water which was infected 

 with typhoid and coli respectively (in the manner indicated on 

 p. 410). 



The flasks containing these infected unsterilised Thames waters 

 were kept at a winter (6 8 C.) and a summer (19 C.) temperature 

 respectively, and were examined from time to time by gelatine plate 

 cultivation, and the results of these periodical examinations are 

 recorded in the following table : 



