23 



of the shell was 1 c.c., it has to be mentioned that while 

 the injection was proceeding a little fluid, about the same 

 quantity that was being injected, was escaping from the oyster 

 near the lock, so that although this escaped fluid appeared 

 to be the clean water from within the shell, and although 

 the injection was made fairly gradually, we cannot suppose 

 that none of the injected bacilli escaped with the water. At 

 any rate, the above amount of B. typhosus was injected into 

 the shell of each of 12 oysters. Of these six were put back 

 into the sterile sea water, the other six were transferred to a 

 plate and placed in the cold chest. The first six will be 

 designated as " wet oysters," the other six as " dry oysters." 

 The analyses of the latter would show whether any, and what, 

 changes took place in the number of B. typhosus as com- 

 pared with the wet oysters. It is well known that oysters 

 after they are removed from their ground are, in many 

 instances, not consumed at once, but are occasionally kept 

 for days at the wholesale dealer's or the retailer's in a " dry " 

 state, in barrels, bags and the like ; in fact, oysters imported 

 from a distance must of necessity be so kept. As regards 

 the "wet" oysters the sea water (2000 c.c.) was changed 

 after 24, 48, 72, 96 and 144 hours, that is to say, after one, 

 two, three, four and six days. 



The oysters analysed were taken in this order : Oyster 1, 

 wet, after having been one day in clean water ; oyster 2, dry, 

 having been kept dry one day ; oyster 3, wet, after two days 

 in clean sea water ; oyster 4 having been kept dry for two 

 days, and so on. 



Oyster 1 was taken out of the sea water after one day, its 

 outer surface well brushed under the tap, then dried with a 

 clean cloth, opened with sterile knife, the liquor drained off 

 as well as possible, then minced with sterile scissors in a 

 sterile glass dish, well mixed and the turbid fluid measured. 

 It amounted to just one cubic centimetre. From this fluid 

 made two Drigalski plates, each with yj^ c.c., i.e., 10 cubic 

 millimetres. 



After incubation for 48 hours the colonies, all of the colour, 

 aspect, and nature of B. typhosus there were no others 



