LETTER Xlll. 



135 



else — the corresponding portions of that layer in the 

 shoots that remain in connection with the tree being 

 all converted into " wood," The like occurrence takes 

 place in the process of propagation by layers." A 

 branch of a tree is turned down, and part of it placed 

 under ground. From the whole of that portion of the 

 Cambium of the branch which is thus brought into 

 relation with the soil, and which, under ordinary cir- 

 cumstances, would have been transformed into ''wood," 

 true roots come off. 



3. Again, consider what is presented to our view in 

 the Elm at North Stoneham, to which I formerly 

 referred. Read again what I said in my ffth letter 

 (section 9) respecting it; and consider this further, 

 that from all that portion of it which was cut or torn 

 and brought into contact with the air — and which was 

 left unsupported and unfettered by the cellular tissue 

 — the Cambium-layer sent down fibres and bundles of 

 fibres, the radicular character of which is beyond all 

 question. In a little volume, entitled The Book of 

 Trees^^ another example of the like kind is described 

 and figured as it presented itself in an old Oak on the 

 banks of the Wear, a few miles from Durham. In 

 this case, the roots that were sent down from the 

 upper part of the decayed bole, not only made their 

 way down and struck into the ground; but being 

 cabined and confined within the chasm which they 

 * Published by J. W. Parker : 3d ed. Pp. 30, 31. 



