22 CIRCULATION OF THE SAP. 



gigantic tulip tree in Western New- York, which was found 

 to be ninety years old at the discovery of Columbus. The 

 pines on the Californian coast, which attain such enormous 

 dimensions, have in some instances numbered nine hundred 

 rings. Consequently, they would have served as bean-poles 

 as far back as the time of Genghis Khan, and must have 

 been towering forest trees of two hundred years of age 

 during the conquests of Tamerlane. 



The reader will perceive that the roots and leaves perform 

 each a most important part in the growth of the tree ope- 

 rating as they do at the opposite extremes of this wonderful 

 piece of machinery. The roots are indispensible in receiving 

 and furnishing the liquid portions, the crude material, 

 from the soil ; the leaves are the manufactory, equally ne- 

 cessary, for working up this crude material into the new 

 wood; while the microscopic tubes become the carrying 

 agents for conveying first the material to the leaves, and 

 afterwards to the store-house along down the branches and 

 stem where it is deposited. 



Hence, neither of these organs can be destroyed or re- 

 moved without the destruction of the plant or tree. The 

 roots, however, being placed beneath the soil, are safe from 

 ordinary accident ; but unless properly supplied with moist- 

 ure, with the minute portions of the soil, as potash, lime, 

 &c., in solution, so essential to growth, they cannot furnish 

 the leaves with what they need. This explains the reason 

 that in a good bed of mellow earth, which receives and 

 holds a due quantity of water, and admits the free extension 

 of the minute and delicate roots, any tree will flourish so 

 much better than in a hard soil, overcharged perhaps at one 

 time and destitute of water at another, or in grassy and 

 weedy ground where the soil is robbed of a large portion of 

 the necessary materials before the tree can get its due sup- 

 ply. 



If destitute of leaves, nourishment, however abundantly 

 furnished by the roots, cannot be manufactured for the 

 growth of the wood nor of the fruit. Hence, trees kept 

 simply stripped of their foliage for a length of time, perish ; 

 leaf-eating insects in this way do great injury; and leaf- 

 blight, or any other disease of these organs, is always more 

 or less detrimental to growth, if not fatal to the tree. Seve- 



