BACTERIOLOGY OF THE OYSTER. 



31 



*Not examined. 



It will be noticed that in the last two columns of the table is given 

 the score based upon the shell liquor alone and upon the shell liquor 

 and the "washings" from the oyster combined. The method of 

 scoring is based upon the same principal as the method of scoring 

 recommended by "Standard Methods," but it works out a little 

 differently for the method of analysis followed by the writer is not 

 strictly in accordance with "Standard Methods." In the latter 

 method 1 c.c, 1-10 c.c. and 1-100 c.c. quantities of the shell liquor 

 are inoculated into lactose-peptone-bile. If the presumptive test 

 shows B. coli in 1 c.c. dilution and not in the 1-10 c.c. and the 1-100 

 c.c. then the score of this oyster is one. If it shows B. coli in 1-10 c.c. 

 and not in 1-100 c.c, the score is ten; if in 1-100 c.c. the score is 100. 

 In other words, the score of the oyster equals the number of B. coli 

 found in one cubic centimeter of the shell liquor. In the writer's 

 experiments the shell liquor was carefully measured and diluted wath 

 an equal volume of one per cent. NaCl solution. One cubic centi- 

 meter of this mixture was used to make the various dilutions. The 

 result is that the various dilutions contained 3^ c.c, %o c.c and 



