41 



this microbe after two days (two changes) in clean sea 

 water. 



The analysis of the oysters of the dry lot showed : 



Oyster 2 after 2 days dry contained 58,700 B. typhosus per 



oyster ; no B. coli com. 



4 17,400 B. typhosus per 



oyster ; no B. coli com. 



37,900 B. typhosus per 



oyster ; no B. coli com. 



1300 B. typhosus per 



oyster ; no B. coli com. 



,, 10 5, 11 ,, 3, 3, innumerable B. typhosus, 



very large number of 

 B. coli com. 



This oyster always looked weak, it did not close its shell 

 promptly ; when opened, eleven days dry, it had no liquor 

 in the shell, and it looked abnormal, brownish. This, there- 

 fore, must be considered as an abnormal case, in which 

 the activity of the oyster tissues was unhealthy and in 

 abeyance, and this would explain the inability of the fish 

 to deal with either the B. typhosus or the B. coli, both these 

 microbes having been capable of multiplying in the 

 oyster. 



Omitting this abnormal oyster, we see, then, that also in 

 this experiment the dry oysters did not clean themselves in 

 anything like the same extent as did their wet companions : 

 this is in agreement with the results of the previous experi- 

 ments, in which clean oysters were used. It is noteworthy 

 that also the dry oysters were able to effectually deal with 

 the B. coli communis in two days, which clearly points to 

 the conclusion that the tissues and activities of the normal 

 oyster per se are as inimical to the B. coli communis as to the 

 B. typhosus, both being as regards the oyster aliens, and there- 

 fore when found in the oyster must have been derived from 

 the surroundings. 



Table IV gives the summary of this Experiment IV. 



