46 BACTERIOLOGY OF THE OYSTER. 



COMPARISON OF THE BACTERIAL CONTENT OF THE 

 STOMACH AND OF THE SHELL LIQUOR OF OYSTERS. 



Houston in his report to the local Government Board, 1904, makes 

 the following statement: ''The experiments detailed elsewhere seem 

 to indicate that per unit of volume the gastric juice of the oyster is 

 more impure bacteriologically than the oyster liquor." The experi- 

 ments upon which this statement is based are taken up in some detail 

 under "Bacteriology of the Shell Liquor and 'Washings' from the 

 Body of the Oyster," and so it is not necessary to take up these 

 experiments in this connection. The -writer has shown that these 

 experiments and the conclusions drawn are not based upon sound 

 assumptions and so these results are not to be relied upon. 



Clark, ^ in a long series of experiments has shown that in both 

 clams and oysters the shell liquor is much more likely to yield B. coli 

 or sewage streptococci than either the stomach, intestine or rectum. 



Both of these workers studied the B. coli content of the different 

 parts of the oyster. The writer could not obtain any badly polluted 

 oysters at the time of year during which the experiments were con- 

 ducted and so he examined the shell liquor and stomach contents 

 for the total number of bacteria which each part contained. It 

 would have been possible to infect oysters artificially with the colon 

 bacillus, but it is not certain that one could simulate natural conditions 

 exactly and consequently wrong conclusions might be draw^n. We 

 have no reason to suppose that B. coli are distributed other than 

 equally among the other bacteria in the oyster and so a comparison 

 of the total quantity per unit volume ought to show the relative 

 frequency with which one would expect to find any particular bacter- 

 ium in either part of the oyster. 



In this series of experiments forty-one oysters were used. The 

 method of examination was as follows : — The juice of each oyster was 

 collected in a small glass-stoppered bottle which was calibrated in two 

 cubic centimeter divisions. The amount of shell liquor was read off 

 in cubic centimeters and diluted with an equal amount of one per cent, 

 sodium chloride solution. The shell liquor and the sodium chloride 

 solution were shaken vigorously one hundred times and one cubic 

 centimeter of this mixture was transferred to a tube containing nine 

 cubic centimeters of one per cent, sodium chloride solution and 



^Report State Board of Health of Mass. 1905, 428. 



