318 LONGEVITY OF TREES. 



tioned, that all vegetable matter is, during growth 

 and for some time after it is perfected, preserved from 

 decay by the life ; and after this has entirely left, it 

 endures for an uncertain period before its final decom- 

 position by the vicissitudes of weather. The natural 

 death and destruction of a tree happens in conse- 

 quence of the wood, in the greater number of kinds, 

 becoming rotten at the core, which defect continues 

 to increase outwards till the whole axis is perished ; 

 of course the tree is then shattered to pieces by the 

 wind. 



The age of trees, when no record of their planting 

 has been kept, cannot be ascertained until they are 

 felled ; at which time the concentric layers composing 

 the axis may be seen and numbered; the amount 

 from the pith to the circumference being equal to the 

 age of the tree, or, in the pine tribe, the number of 

 knots from the base to the apex of the tree. This 

 cannot be done accurately unless the whole butt be 

 sound ; because if the tree has stood beyond a certain 

 time, a portion of the centre will be rotten, and then 

 the age can only be guessed at. Nor, even if the 

 age were ascertained, would it be a criterion for judg- 

 ing of the age of other trees of similar magnitude, 

 unless the soil and situation in which they grow be 

 exactly alike. 



We have histories of remarkably large trees grow- 

 ing in different parts of the world ; as some of the 

 Bombacecz in Africa, the figs of India, the chestnuts 

 of Sicily, the cypresses of Mexico, the pines of Cali- 



