52 I) A VET'S PRIMER 



"That's a dandy!" 



I should say so! Frank. Now, turn back to the 

 last page and the one preceding. Great contrast, is 

 there not? The former are dying of thirst; this has 

 all the water it needs. How much water do you think 

 there is in the leaves of this beautiful maple? Of 

 course you have not yet had the chance of figuring 

 this out, so I will tell you : There is almost forty 

 gallons, or nearly a barrel and a quarter! 



" How do we know this? " 



That's a good question, Bertha. Our botanical 

 professors have wonderful instruments for finding this 

 out. At the Experiment Station at the University of 

 Vermont (Burlington, Vt.), some very valuable experi- 

 ments have been made. According to the basis of 

 measurements for leaf area the tree in this photograph 

 ,has leaves enough, if they were spread out and laid side 

 by side, to cover more than half an acre of ground. 

 The leaves will stand on the tree, fresh, all' through a 

 hot day. But cut off a twig, and see how soon the 

 leaves droop ! The speed with which it wilts shows 

 you how fast the water escapes. Taking the figures 

 that botanists give us I find that this maple takes up and 

 throws off, through the leaves, some five hundred barrels 

 of water, from the first of May to the first of December. 



From such figures you may get some idea what 

 effect there has been brought about by destroying the 

 native forests. Think of a million large trees throwing 

 500,000,000 barrels of water into the atmosphere in one 



