410 Profs. Percy Frankland and Marshall Ward. 



pare the respective behaviour of the two organisms in these three 

 different states of the Thames water. 



The infection of the several waters was made on 11.5.1893, as 

 follows : 



I. Typhoid. Forty needle-loops were removed from the surface of 

 an agar-culture of the typhoid bacillus which had been grown at 

 18 20 C. for fourteen days, great care being taken to carry as little 

 as possible of the culture-material along with the growth. This 

 growth was introduced into 50 c.c. of steam-sterilised Thames water 

 and violently shaken for fifteen minutes in a sterile bottle to 

 thoroughly disintegrate the masses. This water-dilution was then 

 employed for the infection of the larger quantities of water as indi- 

 cated below. 



II. B. coli. The water-dilution of the B. coli communis was made 

 in exactly the same way as that of the typhoid bacillus described 

 above, excepting that only twenty-five needle-loops of the growth 

 were taken, as owing to its greater thickness it was detachable in 

 larger masses from the surface of the agar. The culture employed 

 was of just the same age (fourteen days), and had been grown at the 

 same temperature (18 20 C.) as the typhoid bacillus. 



With the water-dilutions thus prepared the following infections 

 were made : 



Typhoid bacillus. B. coli communis. 



Unfiltered Thames Water. 



2000 c.c. received 8 c.c. of 1000 c.c. received 3 c.c. of 



the water dilution. the water dilution. 



Porcelain-filtered Thames Water. 



750 c.c. received 3 c.c. of 750 c.c. received 2 c.c. of 



the water dilution. the water dilution. 



Steamed Thames Water. 



750 c.c. received 3 c.c. of 750 c.c. received 2 c.c. of 



the water dilution. the water dilution. 



The waters thus infected were each subdivided amongst a number 

 of smaller sterilised flasks plugged with sterile cotton-wool, and these 

 were respectively placed in the incubator or refrigerator, according as 

 they were to be exposed to a winter or a summer temperature. Thus : 



INFECTED. 



Typhoid. B. Coli. 



Unfiltered Thames Water. 



3 flasks incubator. 3 flasks incubator. 



3 refrigerator. 3 refrigerator. 



