BACTERIOLOGY OF THE OYSTER. 45 



biology of the oyster. The optimum temperature for the growth of 

 the oyster is, probably between 20° C. and 25° C. At this temperature 

 the cells of the oyster are most active. The mucus sells will secrete 

 a larger amount of mucus than at decidedly lower temperatures. 

 The more mucus secreted the more will remain clinging to the body 

 of the oyster. Generally speaking the greater the amount of mucus 

 the greater the number of bacteria we would expect to find in the 

 mucus on the outside of the body. As the temperature of the water 

 lowers, the metabolic processes of the oysters are correspondingly 

 slowed and a smaller amount of mucus and for this reason fewer 

 bacteria will be found on the body of the oyster. For this reason it 

 seems fair to assume that the apparent relation between the tempera- 

 ture of the water and the proportion of B. coli on the outside of the 

 oyster and the shell liquor is real and not accidental. 



These two sets of experiments throw light on the findings of Houston 

 cited above. It is easily seen that simply pouring water over the 

 body of the oyster is not sufficient to remove all the bacteria. The 

 experiments of the writer on the comparison of the bacterial content 

 of the stomach and shell liquor shows that per unit volume the shell 

 liquor contains on the average over twenty times as many bacteria 

 as the stomach juices. Evidence from all sides shows that Houston's 

 assumption that all the bacteria were washed from the body of the 

 oyster by simply pouring water over the oyster and further that the 

 bacteria found in the minced meat of the oysters so treated came 

 entirely from the stomach are not in accordance with the facts. 



These experiments show the necessity of examining not only the 

 shell liquor, but also the mucus on the outside of the body of the oyster. 

 This is especially true during the warmer months. At this time 

 there are on the average many more B. coli on the body of the oyster 

 than is contained in the shell liquor. It is perfectly legitimate to 

 consider the mucus on the body of the oyster as part of the oyster 

 juice. If we so consider the mucus, it makes a very decided difference 

 in the score of the oyster. In one instance the combined score of one 

 oyster was ninety-six times the score based upon the shell liquor alone. 

 The combined score is never less and often many times more than the 

 score based upon the shell liquor. If there were any constant 

 relation between the B. coli content of the shell liquor and the mucus 

 removed from the body of the oyster, the examination of the shell 

 liquor alone would be sufficient. But as no such relation exists the 

 necessity of examining both the shell liquor and the mucus is at once 

 apparent. 



