53 



Mussel 5 (medium), 5 days after change, contained over 58,000 



B. typhosus. 

 ,, 6 (medium), 6 days after change, contained over 6000 



B. typhosus. 

 ,, 7 (medium), 7 days after change, contained 14,200 B. 



typhosus. 



SEEIES C. 



EXPERIMENTS WITH OYSTERS KEPT IN STERILE SEA. WATER 

 INFECTED WITH HUMAN F^CAL MATTER. 



In the foregoing experiments (Experiments IV and V), 

 we had the opportunity of showing that, just like the 

 B. typhosus, so also the B. coli communis when originally 

 present rapidly disappears from the oysters and cockles if 

 these be kept in clean surroundings. As this question of 

 the presence of B. coli has recently received a great deal of 

 attention, and caused a radical divergence of opinion, we 

 propose to discuss it somewhat in detail, but first wish to 

 record some experiments made expressly to determine in exact 

 manner how oysters are capable of dealing with the B. coli 

 communis, derived from human faecal matter. This deter- 

 mination by means of Drigalski plates is extremely simple, 

 since the colonies of this microbe are already after 24 hours 

 at 37 C. conspicuous by their size, by their red colour and 

 marked red halo. 



EXPERIMENT VII. 



One gram of faecal matter of a healthy man was shaken 

 up in 2000 c.c. sterile sea water, a determination was made 

 by means of a Drigalski plate with ioo~oo P ar ^ f a cubic 

 centimetre (1 c.c. of the sea water emulsion was added to 

 99 c.c. sterile water : dilution 1 ; of this 1 c.c. was added to 

 9 c.c. sterile water : dilution 2 ; -j- 1 ^ c.c. of this dilution 2 

 was used for the Drigalski plate). This plate showed, after 

 incubation at 37 C., 23 colonies of B. coli communis. These 



