26 SAGACITY AND MORALITY OF PLANIS. 



But in an aninaal's body (at least in the higher 

 kinds) the blood is sent to every part by means of 

 that special muscular organ, the heart. In a plant 

 or tree, no matter how large it is, no special arrange- 

 ment of this kind exists for pumping the nutritious 

 fluid. Nevertheless, the sap, or vegetable blood, 

 finds its way to the extremest tip of the farthest twig ! 



Nature is seldom embarrassed for want of a device. 

 Indeed, her extremity is usually her best opportunity. 

 By means of " capillary attraction " the identical 

 method which causes water to be " sucked up " by 

 a dry sponge, or to permeate a mass of dry loaf- 

 sugar, the sap in plants rises and passes upwards 

 and onwards through the entire tissues of every 

 plant. This upward flowing is much helped by 

 the leaves, which in the daytime imperceptibly give 

 off a great deal of water. In this way the leaves 

 of an ordinary -sized Sunflower will transpire as 

 much water as a man perspires. Thus the moisture 

 containing mineral salts is always entering in at 

 the roots, whilst it is evaporating at the leaves. It 

 is like drawing water at a tap which cannot be 

 drawn off there without the entire volume of water 

 in the pipe being on the move. Even the wind, 

 by rocking trees and plants to and fro, helps to 

 pump the sap upwards. By one or other or all of 

 these means the nutritious fluid of plants is as cer- 

 tainly diffused to every part as if each possessed a 

 heart for the special purpose of suppljang it ! 



