258 ELEMENTS OF WATER BACTERIOLOGY 



B. The icing of the samples, if they are not to arrive 

 at the point of laboratory examination inside of 36 hours, 

 or if the outside temperature is above 50 F. 



It is not necessary to enclose the oysters in an absolutely 

 tight container, providing the above conditions are main- 

 tained. 



Condition of Samples. Record shall be made of the 

 general condition of the oysters when received, especially 

 whether the shells are open or closed; of the presence of 

 abnormal odors; and of the temperature of the stock. 



Technical Procedure. The bacteriological examination 

 shall be started as soon as possible after the receipt of the 

 sample. 



The oysters shall be thoroughly cleaned with a stiff 

 brush and clean running water and then dried. The edges 

 of the shell shall be passed through the flame or burned 

 with alcohol. 



The opening of the shell shall be accomplished by either 

 of the following methods: 



A . By the use of a sterile oyster knife in the usual manner. 



B. By drilling through a flamed portion of the shell 

 near the hinge with a sterile drill. The drill shall be 

 sterilized, and the site of the operation on the shell shall 

 be flamed at least once during the drilling process. 



Bacterial Counts. Bacterial counts shall be made of 

 a composite sample of each lot obtained by mixing the 

 shell liquor of five oysters. Agar shall be used for the 

 culture medium and in general the procedure shall be in 

 accordance with the method recommended for the exam- 

 ination of water by the Committee on Standard Methods 

 of Water Analysis of the American Public Health Association. 



The water used for dilution purposes shall contain i per 

 cent of sodium chloride, in order to approximate the natural 

 salinity of oyster liquor. 



The agar plates shall be incubated at 20 C. for three 

 days and the colonies then counted. 



