III.] WATER CULTURES 43 



In order to demonstrate some of the other actions of 

 roots, it will be as well at this stage to raise plants in 

 water culture ; barley or maize form convenient plants, 

 so a few grains should be germinated in damp sawdust 

 or between the folds of a roll of blotting paper standing 

 vertically with the bottom just dipping into water. 

 Choose some twenty-ounce bottles, fit the necks with 

 corks, and make up a solution as follows, dissolving the 

 ingredients separately and mixing them with the bulk 

 of the liquid in the order given : — 



Water ..... i litre. 



Potassium Nitrate . . . i gramme. 



Magnesium Sulphate . . . 0-5 „ 



Calcium Sulphate . . . 0-5 „ 



Sodium Chloride . . . 0-5 » 



Monopotassium Phosplinle . • 0"S » 



Ferric Chloride . • . trace. 



Wrap the outside of the bottle with stout brown 

 paper, and tie it in position so as to keep the contents 

 in the dark. When the seedlings have grown far enough 

 to show a little shoot and roots an inch or more long, 

 split the corks and cut a notch in the split surface, then 

 fix one of the grains in the notch between the two halves 

 of the cork, and insert them into the bottle, so that the 

 tips of the roots just dip into the liquid. If the notch is 

 too large, a little cotton-wool may be necessary to fix the 

 grain in position. Put the bottle in the window so that 

 the little plant gets full light; if water is added to 

 the bottle from time to time to restore what has been 

 lost by evaporation, the barley or maize plant will grow 

 in a perfectly normal manner and will ripen seed in due 

 course. It will be obvious from the way in which the 

 water has to be constantly renewed in the bottle when 

 the growth is active, that the process of taking in water 

 is assigned to the roots of the plant, as indeed might 



