22 



LETTERS ON TREES. 



to US, — and that, too, as I before observed, notwith- 

 standing the facihties within our reach for making 

 observations in regard to them. Each one of every 

 species is looked upon as a single individual in the 

 same sense that each one of every kind of animal is so 

 regarded ; and while it is believed to be subject to the 

 law of mortality and to the law of a determinate 

 stature, it is believed to be also, as compared with any 

 known animal, very long-Uved, and capable of attain- 

 ing to a gigantic size. No more precise idea, however, 

 as to either its longevity or its size is entertained or 

 seems possible ; and even this conception of both is 

 beset with considerations of perplexity. 



15. It is no doubt true, as Professor Balfour ob- 

 serves, that the duration of the life of trees exceeds 

 so much the limit of man's hfe, that it is not easy to 

 collect data on the subject." It is true, also, that even 

 were "tradition" more to be relied on than it is, 

 most trees are already old before they come to be 

 objects of historical interest. But their past history 

 is not therefore buried in oblivion. And it is a suffi- 

 cient answer to both the difficulties now started, to say, 

 that every tree carries within itself the record of its 

 birth and of its career through life. Each year that has 

 passed over it has left its impress upon it. We have 

 only to count the cylinders of wood it has gathered 

 round it, to know how old it is — to examine the thick- 

 ness of the several cylinders, to determine what the 



