438 Profs. Percy Frankland and Marshall Ward. 



From the above table it will be seen that the addition of common 

 salt to the typhoid-infected unsterilised Thames water occasioned an 

 enormous increase in the number of water-bacteria, the effect being 

 most pronounced in the case of the water to which 3 per cent, 

 addition had been made, whilst the water which had received an 

 addition of only O'l per cent, of sodium chloride gave results which 

 did not differ materially from those yielded by the water to which no 

 salt had been added. 



The addition of salt was by no means conducive to the welfare of 

 all the different kinds of water-bacheria present, but, on the contrary, 

 from the appearance of the plate cultivations, it was evident that 

 some forms were favoured at the expense of others ; thus, on the 

 plates prepared from the 3 per cent, salt water, there was a con- 

 spicuous absence of liquefying colonies, these plates having, in fact, 

 almost the appearance of pure cultivations. This entirely bears out 

 what I found a number of years ago (" On the Multiplication of 

 Micro-organisms," ' Proc. Roy. Soc.,' 1886), that in a water containing 

 only a very limited number of species there is generally far more 

 extensive multiplication than in the case of one containing many 

 different species. 



The manner in which the salt operated is most apparent from that 

 flask of the water to which an addition of 3 per cent, had been made, 

 and which was preserved in the refrigerator (6 8 C.), as in this 

 case the multiplication took place most slowly. Thus, whilst the 

 water at the outset contained 78,000 bacteria per c.c., of which nearly 

 all were typhoid bacilli, after six days there were only 300 bacteria 

 per c.c., so that there must have been an enormous destruction in the 

 interval, but the bacteria left subsequently underwent enormous 

 multiplication, although more slowly than in the case of the corre- 

 sponding flask kept in the incubator (19 C.). 



In all cases it will be seen that the multiplication was followed by 

 decline, but this decline was greatly retarded in those waters which 

 had received the large additions of salt. 



We must now consider the effect of these additions of salt on the 

 typhoid bacilli in the waters, as indicated by the results of phenol 

 broth- culture. 



These saline waters were first submitted to phenol broth-culture on 

 29.5.1893, with the following results : 



