31 



(every 24 hours) changed, was analysed for B. typhosus, in 

 order to obtain an insight into the problem whether and to 

 what extent the decrease of B. typhosus is referable to a 

 " washing-out " process. The experiment was made in the 

 following manner : 



Of Experiment II six oysters of the wet lot and four 

 oysters of the dry lot were left over ; they were transferred 

 to a fresh sterile tub into 2000 c.c. of sterile sea water ; the 

 tub and the 2000 c.c. sterile sea water were changed every 

 day for three days. Seeing that the previously wet oysters 

 were already free of B. typhosus at the termination of Ex- 

 periment II, and seeing that in the previously dry oysters 

 the number of B. typhosus had, by the end of Experiment 

 II, come down to 90 per oyster, it was quite in accordance 

 with fact to suppose that if these previously dry oysters 

 are placed for further three days in clean sea water they 

 would be free of the microbe. I am referring to the ascer- 

 tained fact that in clean sea water the previously wet oysters 

 had in two days from 82 B. typhosus per oyster come down 

 to ; three days in clean sea water would therefore, in all 

 probability, bring down the number 90 B. typhosus (oyster 

 14) to B. typhosus. At any rate, whether or no some stray 

 B. typhosus are left in the oyster, it would not fundamen- 

 tally alter the nature of the Experiment III, in which the 

 remaining oysters were placed in sea water reinfected with a 

 large number of B. typhosus. 



To 2000 c.c. of sterile sea water in a flask, emulsion of B. 

 typhosus, made by distributing in sterile sea water a 48 hours 

 old pure agar culture of B. typhosus, was added. 1 c.c. of 

 the infected sea water of the flask was added to 99 c.c. sterile 

 water; of this dilution a Drigalski plate was made with 

 2 J-Q- c.c. The infected sea water was then poured over the 

 above 10 oysters (two batches) in a clean sterile tub. These 

 two batches were kept well separated in the tub, and will be 

 described as "previously wet" and "previously dry " oysters, 

 both batches, however, being kept, now and afterwards, in the 

 sea water in the tub, as will be presently described. 



The Drigalski plate yielded on incubation 118 colonies of 



