76 EFFECTS OF FORESTS ON MARSHES. 



year. Of the energy and rapidity with which water ascends through 

 the trunk of a tree, the operation called boucherie, for the preservation 

 of timber, affords a remarkable example. In a very short time a 

 poisonous liquid is transmitted from the base of the trunk to the ex- 

 tremity of the branches. 



" From whence comes the water so rapidly transpired by the 

 foliage ? Certainly from the soil ; and as the roots of these vegetable 

 giants penetrate far — as some say, in some cases, to the same extent 

 as the branches — -it is easy to understand how the ground becomes 

 di'ied up and incapable of supplying nourishment to plants of smaller 

 growth. 



" It is therefore impossible for anything to thrive close to, or even 

 at a considerable distance from, the root of a tree. It is not only the 

 shade and the want of rain that hinders growth : indeed, plants at 

 some distance from a large tree are as much shaded as are those 

 close beside it, and the rain, which seldoms descends vertically, 

 always moistens such plants more or less, they are also refreshed by 

 the dew, and, nevertheless, they die or languish. It is because they 

 grow in a soil which is always dry and deprived of nourishing power. 

 Certainly the invitation addressed by the oak to the reed in the fable 

 bespeaks a good disposition ; but had it been accepted the poor reed 

 would soon have died of thirst. Its tall and powerful protector 

 would soon have dried up the damp borders of the kingdom of the 

 wind, which nature has appointed as the habitation of reeds. 



" Whoever has uprooted old trees must have remarked to what a 

 great depth the earth around the roots is exhausted and dried up. 

 This state of things can be easily acounted for, after the particulars 

 of the following experiment may have been read. 



" We placed in a large jug of water, as tightly closed up as possible 

 so as to hinder the effect of natural evaporation, the end of an oak 

 branch, 1™ 40 centimetres [nearly 5 feet] long, and 4 centimetres 

 [nearly 2 inches] in circumference at its lower extremity. The 

 branch was cut off from a tree about 25"" [upwards of 80 feet] high, 

 add 2™ 63 centimfetres [about 9 feet] in circumference at 1™ [40 inches] 

 from the ground 



After twenty-four hours' exposure in the open air at a temperature 

 of 15° 7" [60° Fahr.] at the minimum, and 25° 7' [77° Fahr.] at the 

 maximum, the water in the vase diminished 510 grammes [18 oz.]. 

 The sun was shining brightly. In forty-eight hours from the be- 

 ginning of the experiment the water in the jug had again lost 300 

 grammes [10 J oz.] of its weight. The sun had been very warm, the 



