22. 



OF THE FREE DIATOMACEJE. 



suspended, or fixed, in an upright position. To the lower 

 part is attached a short piece of india-rubber tubmg, 

 ending in a glass mouthpiece with a fine opening, and 

 provided with a kind of tap, known in Germany as a 

 4 Quetschhahn,' which may be freely interpreted 4 spring - 

 tap.'* The Algae having been partially cleansed from 

 sand and dirt, the mass is poured into the upper opening 

 of the tube, and a short time being allowed for settle- 

 ment, the tap is opened, and a portion drawn off into a 

 glass. The tap being again closed, and a few minutes 

 allowed to pass, some more of the water is run into a 

 second glass , and so on, a longer period being allowed 

 between each opening of the tap, until the whole of the 



* As this peculiar and most useful form of tap is, I believe, un- 

 known, or nearly so, to English Diatomolo^ists I append a short 



'description. It con- 

 sists, as shown in 

 the accompanying 



Fig. 35. 



Fig. 36. 



figures, of an elastic 

 wire bent round to 

 form two parallel 

 sides, which are 

 again bent at right 

 angles to its axis, so as to cross one another, 

 and each ending in a flat button A, B. Its 

 elasticity, when made to grasp the india-rubber 

 tubing, completely prevents the passage of a 

 fluid. If it is desired that the fluid should 

 escape from the tube, it is only necessary to 

 press the buttons A, B, upon which the two 

 sides separate to any required extent. On re- 

 leasing the buttons, they immediately fall back 

 to their former position, and the flow of liquid 

 B is arrested. 



This instrument (which may be procured at 

 Mr. Bakers. 243, High Holborn) is greatly to 

 be preferred to the ordinary stop-cock for use 

 in washing Diatomacese ; being cheaper, more, 

 easily cleaned, and far less liable to get out 

 of order, or to be choked by sand or mud. — Ed. 



