44 PL A 'NT PHYSIOLOGY. 



pressing lightly against the glass. Or, emery flour and camphor are said 

 to be excellent. A drill may be used, or even, it is said, a brass cork- 

 borer held in position in a hole bored in a wooden block cemented to the 

 glass. 



To Label a Glass-stoppered Bottle. Write with pencil upon the ground 

 glass of the stopper and it will show through the neck. Also for tem- 

 porarily labelling glassware generally a special colored pencil which 

 marks on glass is obtainable. 



To Prevent Decay in Liquids. A 2% solution of formaline will effect 

 this. In osmotic experiments it must be used in equal strength inside 

 and outside the membrane (see page 62). 



To Cork a Full Bottle or Test-tube. Force in the cork with a fine 

 wire or thread between it and the neck (which will allow the escape of 

 air) and later withdraw this thread. 



To Diminish Wilting in Cut Plants. If shoots are bent over and 

 cut under water, they will as a rule keep from wilting much longer than 

 if cut in air. This is because ordinarily in vigorous plants the air in 

 their ducts is rarefied, and hence more air rushes in from without when 

 the cut is made, thus partially blocking the ducts. When the part below 

 the cut is to be used for root-pressure, etc., this precaution is needless, 

 as the escaping sap will force out the air. 



To Give a Constant Water-supply to Flower-pots, Germinators, etc. 

 Place these in a flat-bottomed saucer (indurated-fiber saucers are par- 

 ticularly good*). Take a wide-mouthed bottle, and select for it a cork 

 of such a size that, when forced into the bottle, it leaves projecting 

 above the neck a length of cork rather greater than the depth of water 

 needed in the saucer to keep the given objects properly wet. Along the 

 sides of this cork deeply file four grooves ; fill the bottle with' water, 

 force in the cork, invert the bottle and stand it on the cork in the middle 

 of the saucer (see Fig. 26). The water will run out through the grooves 

 in the cork until it fills the saucer to the desired depth, after which the 

 water will be held at that level as evaporation proceeds. If it is not 

 convenient to place the bottle in the saucer, it may be placed on a sup- 

 port at a distance and a vent-tube led into the saucer with its end at the 

 proper height above the bottom (Fig. 27). 



To Germinate Seeds. Where only the germination of seeds, and not 

 growth of seedlings, is desired, the best germinators are porous earthen- 

 ware flower-pot saucers, covered with others like them and allowed to 

 soak up water from beneath. If thoroughly sterilized by boiling to start 

 with, the saucer filters out the spores from the water entering it, and 

 seeds germinate to great perfection. Very excellent in place of the 



* Obtainable at small cost from dealers in seeds and gardeners' supplies. They 

 are very useful and much lighter than flower-pot saucers. 



