COMPOSITE NATURE OK A PLANT. 131 



leaves, its wood, bark, and roots, — everything, indeed, that is con- 

 cerned in its life and growth, — there seems to be no reason, no 

 necessary cause inherent in the tree itself, why it may not live in- 

 definitely. Accordingly, some trees are known to have lived for 

 twelve hundred years or more ; and others now survive which are 

 probably above two thousand years old, and perhaps much older * 

 This longevity ceases to be at all surprising when we consider, that, 

 although the tree or herb is in a certain sense an individual, yet it 

 is not an individual in the sense that a man or any ordinary animal 

 is. Viewed philosophically, 



232. The Plant is a Composite Being, or community, lasting, in the 

 case of a tree especially, through an indefinite and often immense 

 number of generations. These are successively produced, enjoy a 

 term of existence, and perish in their turn. Life passes onward 

 continually from the older to the newer parts, and death follows, 

 with equal step, at a narrow interval. No portion of the tree is now 

 living that was alive a few years ago ; the leaves die annually and 

 are cast off, while the internodes or joints of stem that bore them, as 

 to their Avood at least, buried deep in the trunk, under the wood 

 of succeeding generations, are converted into lifeless heart-wood, or 

 perchance decayed, while the bark that belonged to them is thrown 

 off from the surface. It is the aggregate, the blended mass alone, 

 that long survives. Plants of single cells, and of a definite form, 

 alone exhibit complete individuality ; and their existence is ex- 

 tremely brief. The more complex vegetable of a higher grade is 

 not to be compared with the animal of the highest organization, 

 where the offspring always separates from the parent, and the indi- 

 vidual is simple and indivisible. But it is truly similar to the branch- 

 ing or arborescent coral, or to other compound animals of the lowest 

 grade, where successive generations, though capable of living inde- 

 pendently and sometimes separating spontaneously, yet are usually 

 developed in connection, blended in a general body, and nourished 

 more or less in common. Thus the coral structure is built up by 

 the combined labors of a vast number of individuals, — by the suc- 



* The subject of the longevity of trees has been ably discussed by Dc Can- 

 dolle, in the Bibhothcque Universelk of Geneva, for May, 1831, and in the second 

 volume of his Physiologie Vcye'tale : also, more recently, by Professor Alphonse 

 Dc Candolle. In this country, an article on the subject has appeared in tho 

 North American Review, for July, 1844. 



