340 



THE ROOTS OF TREES. 



Spiral wire 

 which causes 



the tenth of an inch in twenty-four hours. Think what it 

 must be in fresh and living plants ! See the different sorts of 

 figures into which the oak, &c, folds from that of the firs. The 

 first fig. 2. BB, the second fig. 3, CC. showing it more plainly 

 than in the circle. Let not the reader suppose, that this is 

 the common warping of wood ; it is the regular fold, always in 

 one figure, and which goes off long before the wood is dry, and 

 only retains it, like the animal muscles, a little while afterlife 

 Folds caused has ceased to linger in it. It is the last power of the muscular 

 hr Hbre^""^*^" ^^''" ^^ ^^^^ vvood, or rather of the spiral wire, I have not yet 

 mentioned this as forming part of the root, because it does not 

 (as in the stem) occupy a separate division in surrounding the 

 nearest sap-vessels to the vital part. But in the wood of the 

 root it circulates round every sap-vessel; separating each cylin- 

 der of wood, and meandering on it from one sap-vessel to ano- 

 ther. (See fig. 4.) Besides penciling out the folds in three 

 distinct rows of spiral wires, in each yearly increase, as at fig. 

 5, I doubt not, therefore, that it is the spiral wire which 

 causes this pecuHar motion, and I am the more persuaded of 

 it, because, though the motion of the firs acts in such a reverse 

 manner, yet the spiral wire accompanies it, so as equally to 

 affect the motion, though in a perfectly different direction. 

 What, then, can be said against the spiral wire being the cause 

 of all motion in plants? The more I see of vegetable life, 

 the more I am convinced of this reality. * From the first I 

 trusted to nature to prove her own truths ; and she will do it, 

 because I am most careful never to make one for her. The 

 spiral wire never retains its power of motion above thirty-four 

 hours after it is taken from a plant, and it is nearly the same 

 with the root. I shall now indicate the extreme difference 

 observed in the roots of firs, when compared with that part 

 in other trees, I must beg Pliny's pardon for detecting him 

 in an error when he says, " that he saw a fir tree planted, whose 

 tap-root measured twelve feet," Now unfortunately, no fir 

 has any tap-root. Such is the aversion their roots have to 

 piercing the earth, that in young trees they will frequently be 

 found with their roots bent back, and thus forming a hook or 

 loop. (See fig. 0.) The roots of the Weymouth pine and sil- 

 ver fir, generally divide into threes, and run an amazing way 

 horizontally underground; but the Scotch and Spruce firs run 



is. 



No tap-root 

 in firs. 



