SEA-FISHERIES LABORATORY. 447 



Or we must adopt a better method of analysis. 

 Clearly, if we only cut up a mussel or oyster into small 

 pieces, some of the bacilli present in the animal's body 

 may adhere to the pieces. We must, in order that the 

 method may be reasonably accurate, grind up the pieces 

 of oyster along with the water in a mortar, so as to 

 make a real emulsion. After practising this I am now 

 convinced that the grinding up must be done with sand, 

 so as really to break down the tissues of the shell-fish. 

 We need not fear grinding up and destroying the bacilli. 



In nearly all the analyses mentioned in this paper 

 five mussels were taken. The soft bodies of the animals 

 were detached by cutting through the muscles attached 

 to the shell, and left in one of the valves. The flesh was 

 then cut up as finely as possible by means of sharp 

 scissors, and the mass was dropped into a mortar and 

 rubbed down with the pestle. Small Wedgwood mortars 

 must be used; glass ones break on sterilisation. In this 

 way an emulsion of 5 mussels is obtained : it is put into 

 a wide-mouthed flask and water added to make the volume 

 of emulsion 250 c.c. 1 c.c. should then contain 0'02 

 mussel. Obviously, all the precautions to secure sterility 

 of apparatus and hands are taken. It is quite 

 unnecessary to do more than wash the hands very 

 thoroughly in hot tap water : blank experiments will 

 show this. 



Neutral-red, bile-salt, lactose agar has previously 

 been melted, and the tubes are contained in a large dish 

 of water at 45° C. Petri dishes are ready, and 1 c.c. of 

 the emulsion is taken from the flask and put into each 

 Petri dish. The 1 c.c. pipettes should be selected for 

 wide apertures, as the capillary orifices used by chemists 

 may block up. If the drop of fluid remaining after the 

 pipette drains be blown out, a bulb containing sterile 



