ROOTS 2 I 



Experiment. Take two wide-mouthed clear glass 

 bottles (Fig. 16) ; fill one nearly full of water from 

 the well or hydrant ; fill the other bottle nearly full 

 of water that has been boiled and cooled ; place in 

 each bottle a slip or cutting of Wandering- Jew 

 (called also inch plant, or tradescantia, and spider- 

 wort), or some other plant that roots readily in 

 water. Then pour on top of the boiled water about 

 a quarter of an inch of oil lard oil or cottonseed oil 

 or salad oil. This is to prevent the absorption of air. 

 In a few days roots will appear on the slip in the 

 hydrant water, while only a very few short ones, if 

 any, will appear in the boiled water, and they will 

 soon cease growing. Why is this ? To answer this 

 question, try another experiment. Take two bottles, 

 filled as before, one with hydrant water and the other 

 with boiled water ; drop into each a slip of glass or a 

 spoon or piece of metal long enough so that one 

 end will rest on the bottom and the other against the 

 side of the bottle, and let stand for an hour or so 

 (Fig. 17). At the end of that time bubbles of air 

 will be seen collecting on the glass or spoon in the 

 hydrant water, but none in the boiled water. This 

 shows us that water contains more or less air, and 

 that boiling the water drives this air out. The cut- 

 ting in the boiled water did not produce roots be- 

 cause there was no air in it and the oil kept it from 

 absorbing any. 



Experiment. Into some tumblers of moist sand 

 put cuttings of several kinds of plants that root 

 readily (Fig. 18), geranium, tradescantia, begonia, 



