540 Profs. Percy Frankland and Marshall Ward. 



days old) of the typhoid bacillus were added to 600 c.c. of steam- 

 sterilised Thames water, which was, on the day of infection and 

 on several subsequent occasions, submitted to plate cultivation with 

 the following results : 



Number of days 



Dates on which plates plates were Number of typhoid bacilli 



were prepared. incubated. in 1 c.c. of water. 



31.1.1894 8 4,895 



2.2.1894 ...... 7 15,372 



5.2.1894 10 11,184 



12.2.1894 7 6,558 



23.2.1894 7 5,795 



6.3.1894 6 6,068 



10.3.1894 9 4,093 



These figures show that unquestionable, although not very exten- 

 sive, multiplication of the typhoid bacilli took place in the water 

 thus infected ; but in order to ascertain whether this proliferation 

 was effected at the expense of the very small quantity of culture- 

 material necessarily introduced along with the bacilli, or at the ex- 

 pense of the organic matter pertaining to the Thames water itself, 

 the following further experiment was made : 



On 23.2.1894, 10 c.c. of the above-infected water, which on that 

 day contained 5795 typhoid bacilli per 1 c.c., were added to 20 c.c. 

 steam-sterilised Thames water, and the latter was then and several 

 times sutsequently submitted to plate cultivation with the follow- 

 ing results : 



Number of days 



Dates on which plates plates were Number of typhoid bacilli 



were prepared. incubated. in 1 c.c. of water. 



23.2.1894 7 1830 



26.2.1894 7 1842 



2.3.1894 6 375 



6.3.1894 6 268 



From these figures it is equally evident that in this case no multi- 

 plication but only numerical decline of the typhoid bacilli took place. 

 If, however, the typhoid bacilli can proliferate at the expense of the 

 organic matter belonging to the Thames water, they should have 

 multiplied in the above experiment, as they were imported into a 

 quantity of water, the organic matter of which had not since sterili- 

 sation been exposed to bacterial life ; but from the fact that they did 

 not multiply, but, on the contrary, only fell off in numbers, it becomes 

 almost certain that the distinct multiplication observed in the former 

 experiment was effected at the expense of the small quantity of food- 

 material originally introduced into the water along with the typhoid 

 bacilli. 



