54 



were visible next day as good-sized red colonies with distinct 

 red halo ; they were all of the same kind and aspect, viz., 

 typical B. coli communis ; this would mean 230,000 B. coli 

 communis per 1 c.c. of the infected sea water, or 460 millions 

 of this microbe per 1 gram of ftecal matter. 



Thirteen Whitstable oysters were kept for 48 hours in 

 sterile sea water, and two of them on analysis by Drigalski 

 plates having been proved to contain no B. coli communis or 

 any other B. coli, the remaining 11 oysters were placed in a 

 clean tub into the above foecally infected sea water. Here they 

 remained for 24 hours. They were now taken out, well rinsed 

 under the tap, and divided into lots six oysters were trans- 

 ferred to a fresh clean tub and supplied with sterile sea water, 

 which was repeated every 24 hours as long as any of these 

 " wet " oysters remained ; four oysters were placed " dry " in 

 cool chamber, and the remaining eleventh oyster was used for 

 analysis. At the same time of the above infected sea water, 

 i.e., kept for the 24 hours, analysis by Drigalski plate was made. 

 Of the sea water, 24 hours after infection with faecal matter, 

 ToVo P art f a cu kic centimetre yielded 177 colonies of 

 B. coli communis, or 177,000 B. coli communis per 1 c.c. 



Oyster 1 after 24 hours in infected sea water treated 

 in the usual manner, yielded 77 colonies of B. coli communis 

 per gJo part of the body that is, 46,200 B. coli communis 

 for the whole oyster. 



Sea water which had been changed and in which five of 

 the infected oysters had been placed was analysed 24 hours 

 after the change, using ^- c.c. direct for one Drigalski plate. 

 This yielded 65 colonies of B. coli communis ; this means 

 650 B. coli communis per 1 c.c. 



Oyster 2, taken from the " dry" lot, one day after removal 

 from infected sea water yielded 8575 B. coli communis 

 343 colonies per ^ part of body. 



Oyster 3, taken from the " wet " lot, one day after change 

 yielded 2325 B. coli communis per whole oyster 31 colonies 

 per ^ part of body. 



The sea water in the tub was analysed having been 

 changed 24 hours previously, as well as the tub into which 



