220 F. MAKTIN DUNCAN ON PREPARING MARINE SPECIMENS. 



a piece of brass tubing six inches in length is tightly fitted, so 

 as to project on either side of the cork. To that end of the 

 tube which wiU project within the jar a loose coil of wire, con- 

 sisting of about half a dozen turns, and about two inches diameter 

 and four inches long, is firmly soldered. Over the loose coil is 

 securely fastened to the tubing a small bag of fine muslin or 

 bolting-silk. The end of the tubing outside the jar is bent at an 

 angle like a spout. Into the second hole is tightly fitted a stout 

 japanned iron funnel, having a rim eight to ten inches in diameter. 

 Into this funnel the contents of the " can " at the bottom of the 

 tow-net is emptied each time it is drawn inboard, and while the 

 waste water flows out through the brass tube, the little muslin 

 or bolting-silk bag prevents the escape of the animals, and the 

 coil of wire keeps the bag expanded and the animals from becoming 

 jammed against the tube by the outrush of water. 



The catch may then be emptied into a smaller glass jar, and 

 while stirring gently with a glass rod, so as to keep the organisms 

 on the move, a small quantity of 4 per cent, formaldehyde is 

 added. After stirring for about five minutes allow the plankton 

 to settle at the bottom of the jar. When the jar is not more 

 than half-filled with the plankton, pour off as much of the fluid 

 as possible and fill up with 4 per cent, formaldehyde, giving a 

 good stir round so as to thoroughly mix. Each store jar should 

 never be more than half fiUed with plankton ; if the jar is then 

 fiUed up to the top with the formaldehyde solution, the organisms will 

 keep all right. It is necessary the following day to pour off the 

 4 per cent, solution, and then fill up with 10 per cent, formalde- 

 hyde. Cork down tightly, and the specimens will require no 

 further attention, and are ready at any time for examination. 



As a cement and varnish for ringing slides I use one composed of 

 equal parts of best asphalt varnish and best marine glue, plus 

 three droi)s of castor oil to each ounce of mixed cement. 



I first ring the slide with gelatine (applied warm), and when that 

 has set, paint over with a strong solution of potassium bichromate 

 liberally applied so that it is soaked up by the gelatine ; expose 

 slide to daylight for an hour, which will render the bichromated 

 gelatine insoluble ; then finish off with two or three good coats 

 of the asphalt-marine glue cement, taking care that each coat 

 is thoroughly dry before applying another. 



Journ. Quekett Microscopical Club, Ser. 2, Vol, XIV., No. 87, November 1921. 



