80 ESS A YS. 



guide ; — the more so in this case, as our ordinary conceptions 

 on the subject spring from a false analogy, which we have 

 unconsciously established, between plants and animals. This 

 common analogy might, perhaps, hold good, if the tree were 

 actually formed like the animal, all the parts of which are 

 created at once in their rudimentary state, and soon attain 

 their fullest development, so that the functions are carried on, 

 throughout life, in the same set of organs. If this were the 

 case with the tree, it would likewise die, sooner or later, of 

 old age, — would perish from causes strictly analogous to 

 those which fix a natural limit to the life of animals. The 

 unavoidable induration and incrustation of its cells and ves- 

 sels, apart from other causes, would put an early and sure 

 limit to the life of the tree, just as it does in fact terminate 

 the existence of the leaf, the proper emblem of mortality, — 

 which, although it generally lives only a single season, may 

 yet truly be said to die of old age. But, as the leaves are 

 necessarily renewed every year, so also are the other essential 

 organs of the plant. The tree is gradually developed by the 

 successive addition of new parts. It annually renews not 

 only its buds and leaves, but its wood and its roots ; every- 

 thing, indeed, that is concerned in its life and growth. Thus, 

 like the fabled ^iEson, being restored from the decrepitude of 

 age to the bloom of early youth, — the most recent branchlets 

 being placed, by means of the latest layer of wood, in favor- 

 able communication with the newly formed roots, and these 

 extending at a corresponding rate into fresh soil, — 

 " Quae quantum vertice ad auras 

 ^Etherias, tantum radice in Tartara tendit," 



why has not the tree all the conditions of existence in the 

 thousandth, that it possessed in the hundredth, or the tenth, 

 year of its age? The old and central part of the trunk may, 

 indeed, decay ; but this is of little moment, so long as new 

 layers are regularly formed at the circumference. The tree 

 survives ; and it is difficult to show that it is liable to death 

 from old age in any proper sense of the term. Nor do we 

 arrive at a different conclusion when we contemplate the 

 tree under a less familiar but more philosophical aspect, — 



