102 NEW YORK ZOOLOGICAL SOCIETY. 



7th day, but when removed to fresh sea water they disappear be- 

 fore the 3d and 4th days. 



This is the result of dilution and the action of the sea water. I 

 found that in the sea water used in these experiments B. typhosus 

 was destroyed in from six to eight days, 50 per cent, being de- 

 stroyed in the first 24 hours. 



When the oysters were removed from the infected tank, and 

 kept either directly on ice or else in a compartment of the ice box, 

 as under market conditions, there was a very slight diminution 

 of the number of bacteria per c. c. and a slight increase in the 

 per cent, of B. typhosus present. Thus, if oysters have been in- 

 fected they may retain this infective material, and in this manner 

 may act as disseminators of typhoid fever. 



Now the question arises, Does the oyster ever come in contact 

 with infective material? If it does, does not the fresh sea water 

 over its beds dilute and destroy the organisms ? To this I should 

 say that if the oysters were taken from the beds situated in deep 

 water, where the flood tide brought pure sea water to them, that 

 there would be very slight chance of infection. But it is not from 

 these beds that the oysters are brought to market. » After they are 

 brought up from the natural beds they are generally placed in 

 creeks where the water is brackish, being deposited in small 

 houses built on the edge of the stream. These houses at low tide 

 are nearly dry ; but as the tide rises they become filled with water, 

 which finally covers the oysters, and where a hissing noise can be 

 heard as the oysters suck it in. There being a specific gravity 

 less than that which has covered the oysters on their native beds, 

 there occurs, owing to osmosis, an enlargement of the oysters, 

 making them "fat" and plump. This process is therefore called 

 "fattening," and plumping or drinking. 



The great danger in this is, that the streams used for this pur- 

 pose may be contaminated by sewage. Should a case of typhoid 

 fever occur where there is drainage into a stream, oysters may 

 become polluted. This was just what occurred in the epidemic 

 at Middletown, Conn., in 1894, and which was traced directly to 

 oysters fattened on the banks of the Quinepiac River near New 

 Haven. There had occurred a short time before a case of typhoid 

 fever in a person living on this stream, and the discharges had 

 been drained directly into this river. Wherever this lot of oysters 

 had been shipped there had followed typhoid fever in those who 

 had eaten them. 



The conditions are still the same in many places where oysters 

 are shipped to market. In one stream I took samples of the water 



