THE RATING OF SHELLFISH 



Example E 



151 



The bacteriological examination of oysters from opened or 

 shucked stock very naturally must be somewhat modified from the 

 method as outlined for oysters in the shell. The stock in the con- 

 tainer from which the sample is to be taken must be thoroughly 

 mixed. The containers (wide-mouthed glass jars) must be steril- 

 ized and should have a capacity of i quart. By means of a suit- 

 able sterilized ladle (may be flamed with alcohol on the spot), 

 half fill the containers with the oysters and seal containers in such 

 manner as to exclude all outside contamination. Unless the exami- 

 nation can be made within 3 hr. after taking the sample, said 

 sample must be placed on ice. It is very desirable to make the 

 bacteriological examination shortly after the sample is taken. 

 The laboratory technique is much as for oysters in the shell, though 

 it must be borne in mind that dilutions higher than o.oi cc. are 

 usually required. The results of the bacteriological examination 

 of the opened or shucked stock shall be expressed in the same way 

 as that specified for oysters in the shell, except that in the calcula- 

 tion for B. coli rating the values for the results of the positive 

 fermentation tests, after confirmation, shall be recorded for each 

 of the inoculations of each and every dilution. All tests are to 

 be made in triplicate, that is, three fermentation tubes are to be 

 inoculated for each dilution used. 



Clams, mussels and other shellfish are to be examined in the 

 same manner as oysters, in so far as this is possible. In opening 



