450 Profs. Percy Frankland and Marshall Ward. 



Plates were again ponred from these potatoes, and very small 

 surface-expansion colonies again obtained, which, however, 

 again were not like those of typhoid, and gelatine tubes in- 

 oculated from these yielded, in course of time, brown surface 

 growths quite unlike typhoid. 



The results of these experiments with the unsterilised Thames 

 water, to which O'l, 1, and 3 per cent, of common salt respectively 

 had been added, are instructive in more ways than one. Thus : 



(1.) They show that the addition of the salt stimulated the 

 growth and. multiplication of some of the water 

 bacteria to an enormous extent, the effect being 

 the most marked with the largest proportion of salt 

 (3 per cent.), whilst the water to which only 0-1 per 

 cent, of salt was added, behaved almost exactly like 

 the untreated Thames water. 



(2.) This multiplication was, as usual, followed by decline, 

 but the saline waters remained, even after six weeks, 

 more densely, and with the larger proportion of salt 

 much more densely, populated than the Thames water 

 to which no salt was added. 



(3.) As regards the effect of the salt addition on the typhoid 

 bacilli present in the water, the experiments show 

 that they were most prejudicially influenced. Thus 

 whilst on the eighteenth day after infection the 

 typhoid bacilli were easily demonstrable in the ordi- 

 nary unsterilised Thames water to which no salt had 

 been added, and also in that which had received 0-1 

 per cent, of salt and which had been kept at 6 8 C., 

 they were not discoverable in any of the waters to 

 which 1 and 3 per cent, salt had been added, nor in 

 that which had received only 0-1 per cent, salt, but 

 which had been kept at the summer temperature of 

 19 C. 



(4.) In the case of the 3 per cent, salt addition, I am of 

 opinion that the rapid disappearance of the typhoid 

 bacilli is largely due to the direct action of the salt, 

 whilst in the case of the smaller proportions it may 

 also be due to the great multiplication of some of the 

 common water bacteria. 



Further experiments on the behaviour of typhoid bacilli in Thames 

 water, to which salt had been added, were subsequently made (see 

 pp. 530, et seq.), they proved entirely confirmatory of the results just 

 recorded above, both as to the stimulation of the multiplication of the 



