18 GENERAL BOTANY 



root-hairs grow out and they become firmly attached to 

 the minute particles of soil, so firmly in fact that it is 

 impossible, even by careful washing, to separate them. 



It is by the combined effect of all the rootlets 

 passing through and round the smallest lumps of earth, 

 and of the countless root-hairs glued on to the ultimate 

 particles of soil, that a plant is fixed in the ground; 

 and so tightly that you will find if you try that it is 

 hard work for a man to pull up even a small shrub 

 or bush unless the soil is very loose, and even then 

 most of the rootlets break. We can thus understand 

 how it is that the tallest and largest trees are not 

 blown down except by winds of unusual violence or 

 when the ground has been softened by rain. 



4. Secondly, as every one knows, plants require 

 water, and the water must be given to the roots. A 

 certain amount can sometimes be absorbed by the 

 leaves, if they are put in water, but only very little. 



Take a small plant, and having cleaned it of all 

 soil weigh it. Then put it in a strong sun for a few 

 hours and weigh it again. It will now weigh con- 

 siderably less. This, of course, is because it has got 

 drier in the sun, and lost water. Now dry it still 

 more over a fire, or in a steam oven, taking care 

 that it is not burnt or even scorched, and that none of 

 it is lost, and weigh it again. There will be a further 

 loss in weight, and you may go on in this way until 

 all the water in the plant has been driven off. 



If you do this simple experiment, you will be sur- 

 prised to find what a large quantity of w r ater a plant 

 contains. At least half the weight of an ordinary 

 woody plant is water. If you do the same with leaves 



