Report on the Bacteriology of Water. 535 



The above table should be compared with that on p. 525 et seq., 

 which refers to the same waters only without the addition of salt. It 

 will then be seen : 



(1.) That in the typhoid-infected unsteriUsed Thames water, the 

 typhoid bacilli had already disappeared on 12.2.1894, i.e., 

 before the addition of salt was made at all, and, therefore, 

 that no inferences can be drawn as to the effect of the salt 

 on the typhoid bacilli in this unsterilised water. Of course 

 the absence of typhoid in this unsterile water was not 

 ascertained until more than a week after this date, 

 12.2.1894, on which the salt was added, otherwise the 

 experiment would not have been made at all. 



(2.) In the typhoid- infected steam-sterilised Thames water, inocu- 

 lated with a few drops of unsterile Thames, the typhoid 

 bacilli were still demonstrable on 19.2.1894, but not on 

 26.2.1894, whilst in the same water, to which 1 per cent, of 

 salt was added on 12.2.1894, the typhoid bacilli were dis- 

 coverable still on 14.2.1894, but not on 19.2.1894. Thus the 

 addition of the salt considerably hastened the disappearance 

 of the typhoid bacilli from what may be called this arti- 

 ficially unsterile Thames water. 



(3.) As already shown by the results of plate cultivation given on 

 p. 531, the addition of the 1 per cent, of salt to the 

 typhoid- infected steam- sterilised Thames water, caused a very 

 rapid diminution in the number of typhoid bacilli present, 

 and these results are entirely confirmed by the results 

 on cultivation with phenol broth. Thus, the last plate 

 cultivation, made on 24.2.1894, revealed the presence of only 

 six typhoid bacilli in 1 c.c., phenol broth-culture still showed 

 the presence of typhoid on 26.2.1894, but no more on 

 5.3.1894, although in the same water, which had not been 

 treated with sodium chloride, the typhoid bacilli were easily 

 discoverable by phenol broth-culture on that day. 



(4.) There can be no doubt, therefore, that common salt, whilst 

 enormously stimulating the multiplication of many forms of 

 water bacteria, exerts a directly aud highly prejudicial effect 

 on the typhoid bacilli, causing their rapid disappearance 

 from the water whether water bacteria are present or not. 



(5.) It is worthyof remark that the typhoid colonies obtained on 

 plate cultivation of the phenol-broth tubes which had been 

 rendered turbid by these infected saline waters exhibited in 

 some cases a very abnormal appearance, being irregularly 

 swollen and lobulated in the depth and often giving rise to 

 whip-like prolongations into the surrounding gelatine. As 



