LETTER I. 



5 



9. If, then, every tree be a single or an individual 

 object, it is plain that, by the laws of its being, it must 

 have a determinate period of life, and a determinate 

 size of organism ; and allowing that neither of these 

 is absolutely fixed any more than in the case of the 

 dog or the horse, but that each may vary within cer- 

 tain limits, there must nevertheless be an average in 

 respect of both for each kind or species of tree — it 

 being of course understood, that all the conditions 

 requisite for its natural life and growth, obtain. And 

 accordingly, the questions before us thus qualified 

 are — " How long does this or that kind of tree natu- 

 rally hve V And, " What is the size to which it natu- 

 rally attains ?" 



10. These questions, you may imagine, must admit 

 of a ready and a satisfactory answer. True, you may 

 feel yourselves unable to answer them, and yet reason- 

 ably presume that our knowledge of all sorts of trees 

 must be complete and accurate enough to make the 

 answers easy to those possessed of that knowledge. 

 They are not far to seek, speaking generally, as regards 

 animals. Migratory as animals are, difficult of access 

 or dangerous of approach as many of them are, these 

 points in their history are accurately known, or may 

 readily be ascertained in regard to a large proportion 

 of them. How much more easily in regard to trees ! 

 Fixed to the soil as trees are, remaining always on the 

 same spot of ground in which they were first planted, 



