324 THK I'HKSENC'E, TVIM-:, AM) I'OSHIlll.K SKiNLKR'ANCK OF liAC'TOSK-KKUM K.STINd HACILLI 



Experiment IV. — Date, July 28, 1910. Local rainfall, nil. 

 Sample taken from Well No. 7 of the Kliartoum water-supply. 



Gas was present in MacConkey's media when the latter was inoculated with 50 c.c. 

 of the sample. 



Sporogeues milk test negative in 20 c.c. 



Group I, nil 



Group II, nil 



Group III, 2 



Group IV, 1 



Prillulion 



greater wilh 

 falling than 

 with rising 

 .Nile 



Conclusions 



One may here state that the observations have, so far, been too few in number to 

 justify any definite conclusions being arrived at with regard to the position that the B. coU 

 occupies in this country as an indicator of recent pollution. Still, some of the experiments 

 show interesting points as regards tlie vitality of this organism in nature. In order to 

 make all these experiments as complete as possible, tests require to be carried out during 

 every month in the year, and it would thus be possible fully to determine the effects 

 of external natural forces such as sunshine and rain on all organisms of faecal origin. All 

 such research would afford valuable information. The drawback in carrying it out is 

 the large amount of media that is required, and in laboratories such as these, where 

 work of another nature requires constant attention, the time necessary to carry them 

 out completely is not available. 



Experiments I. and II. were of interest, as they illustrated that a greater degree 

 of faecal pollution was present in a "falling" than in a "rising" river, although the 

 colony count in the latter was nearly four times as great as in the former. There was 

 a considerable difference in the lowest " end " points in which ftecal bacilli were obtained. 



Out of ten colonies of lactose fermenters present in (1) the rising Nile there were :— 

 B. coU = 5, B. neapolitanus = 1, B. vesiculosus = 1, and three others not identified. 



(2) Falling Nile. 



B. coli = 2, B. neapolitanus — 4, B. vesiculosus =1, B. coli mutabilis = 1, and two 

 others not identified. 



Group IV. was absent in both samples. 



