936 VESETATION. [Lesson xxxtv. 



vessels of the leaf, having exhausted themselves in 

 the formation of the bud, are unable to bring it 

 nearer to maturity. In this state it exactly resem- 

 bles a seed, containing within itself the rudiments 

 of vegetation, but destitute of absorbent vessels to 

 nourish and evolve the embryo. Being surround*- 

 ed, however, by sap, like a seed in moist earth, it is 

 in a proper situation for growing ; the influence 

 of the sun sets in motion the juices of the bud,, 

 and of the seed ; and the first operation in both of. 

 them, is to send forth the roots downwards a cer* 

 tain depth, c or the purpose of obtaining the. neces- 

 sary moisture. The bud, accordingly, shoots down- 

 its root-? upon the inner bark of the tree, till they 

 reach the part covered by the earth. Winter now 

 arriving, the cold and defect of moisture, owing t- 

 the clogged condition of the absorbent vessels,. 

 cause the fruit and leaves to fall ; so that, except, the. 

 provision of buds with; roots, the remainder of the 

 tree, like an annual plant, i entirely dead : the. 

 leaves, the flowers, and fruit, are gone ;. and what 

 was the inner bark is no longer organized, while 

 the roots of the buds form a new inner bark ; and 

 thus the buds with their roots contain all that re- 

 mains alive of the whole tree. It is owing to this 

 annual renovation- of. the inner bark, that the tree 

 increase.? in bulk j and a new coating being added 

 every year, we are iience furnished with an easy 

 and exact method qf ascertaining the age of a tree,, 

 by counting the number of concentric circles of 

 which the trunk is composed. A tree, therefore, 

 properly speaking, is rather a congeries of a mul- 

 titude. 



