126 



LETTERS ON TREES. 



the peculiarity mentioned attaching to all the rest of 

 it. And for that peculiarity I not only see a reason, 

 but in it I see also a singularly ingenious contrivance 

 Fig. 15. to obviate a difficulty which the cir- 



cumstances of trees create, and to 

 meet which a strict adherence to 

 the rule of ordinary annuals would 

 have been a clumsy expedient. 



8. For observe : great as is the 

 known power of roots in making 

 their way through obstacles to the 

 soil, and far as they will often tra- 

 vel to reach it. it seems scarcely 

 \^ conceivable that in a tree — say — 

 150 feet high, and with roots 

 stretching perhaps fifty feet under 

 ground, the roots of the young ter- 

 minal plants could, in the course of 

 ^ a few weeks in summer, creep down 

 and traverse the distance of 200 

 feet. That they do not, I admit : — 

 d \\lSliH// ^ nay it is certain that they do not. 



For if they did, it would be easy 

 by a few simple experiments to 

 ascertain the fact, and to measure 

 also the rate of their descent. 

 9. Let us now consider wherein the peculiarity of 

 their formation lies, and how their growth is effected. 



