Lesson xxxiv.j VEGETATION. 23 "i 



the roots. The water and oil, thus imbibed by the 

 roots, is there mfxed with a quantity of saccharine 

 matter, and formed into sap, whence it is distri- 

 buted in great abundance to every individual bud. 

 The amazing quantity of sweet liquid sap provided 

 for the nourishment of some trees, is evident from 

 a prevalent custom in this country, of tapping the 

 birch in the early part of spring; thus obtaining 

 from each tree more than a quart of liquor, which 

 is fermented into a species of wine. This great 

 accession of nourishment, by means of the ascent 

 of the sap, causes the bud to swell, to break through 

 its covering, and to spread into blossoms, or length- 

 en into a shoot bearing leaves. This is the first 

 process, and, properly speaking, is all that belongs 

 to the springing or elongation of trees j and, in 

 many Plants, namely, all those which are annual 

 or deciduous, there is no other process. The Plant 

 absorbsjuices from the earth, and, in proportion to 

 the quantity of these juices, increases in size; it ex- 

 pands its blossoms, perfects its fruit; and when the 

 ground is incapable, by drought or frost, of yield- 

 ing any more moisture, or when the vessels are not 

 able to draw it up, the Plant perishes. But in trees 

 though the beginning and end of the first process is 

 exactly similar to what takes place in annuals, yet 

 there is a second process, which at the same time 

 that it adds to their bulk, enables them to go on 

 increasing through a long series of years. 



This second process begins soon after the first, in 

 this way. At the base of the foot-stalk of each leaf 

 a small bud is gradually formed; but the absorbent 



vessels 



