60 

 TABLE IX. 



PRECEDING EXPERIMENT VII. SEA WATER INFECTED WITH 

 230,000 B. COLI COMMUNIS PER 1 c.c. 



Oyster. 24 hours in infected sea water 46,200 B. coli communis. 



1 day's change .... 2325 



2 days' . . . . 1305 



,, 3 ,, ... . 216 ,, ,, 



4. 11 



}) .... J. 1 J, ,, 



' 5J 5> * 1 }J )J 



5> *" 3J 5> .... U ,, ,, 



This comparison emphasises, therefore, the fact that even 

 when the initial number of the ingested B. coli communis is 

 very large, the oyster is capable of dealing with it success- 

 fully, and it cannot be a question of mere " washing out " by 

 the water of the ingested B. coli, but must depend on the 

 activity of the tissues of the oysters in dealing with the 

 foreign intruder. 



The difference observed here may, it is true, be due to 

 the two samples of oysters coming from different localities, 

 but I hardly think this a satisfactory explanation. If there 

 be an extraneous cause it is more likely to be due to the 

 sample of the oysters used in Experiment VIII not having been 

 quite so good or fresh as those of Experiment VII ; one oyster 

 dying early in the experiment would point in that direction. 

 At any rate, about the fact that even when the initial number 

 of the B. coli communis is very great, the normal oyster is 

 capable in clean water of rapidly clearing itself of this microbe. 

 This fact would, then, once for all set at rest the implied 

 suggestion by the Eoyal Commission on Sewage Disposal, 

 viz., that the B. coli communis is a normal inhabitant of the 

 body of the oyster. If there is one thing clear, it certainly 

 is the fact contrary to that suggestion, viz., it is a fact con- 

 clusively proved that oysters from clean places and oysters 

 kept in clean water are free of B. coli communis ; and 

 further, that if they should happen to have imbibed them 

 from the surrounding water, they, by being again placed in 

 clean water, rapidly clean themselves of the intruder. 



