ON THE FORMATION OF THE BARK OF TREES. 141 



to spring from smooth spaces on the roots and stems of trees, I found 

 every appearance perfectly consistent with the preceding observations. A 

 single shoot only was suffered to spring from each root and stem, and 

 from the base of this, in every instance, the cortical vessels dispersed 

 themselves in different directions. Some descended perpendicularly 

 downwards, whilst others diverged on each side, round the alburnum, 

 with more or less inclination downwards, and met on the opposite side of 

 it. The same pulpous and cellular substance appeared to cover the sur- 

 faces of the bark and alburnum, when in contact with each other, as when 

 detached ; and through this substance the ramifications of the vessels of 

 the new bark extended themselves, appearing to receive their direction 

 from the fluid sap which descended from the bark of the young shoots, 

 and not to be, in any degree, influenced in their course by the direction 

 taken by the cortical and alburnous vessels of the preceding year. 



Whenever the vessels of the bark, which proceeded from different 

 points, met each other, an interwoven texture was produced, and the 

 alburnum beneath acquired a similar organisation : and the same thing 

 occurs, and is productive of very important effects, in the ordinary course 

 of the growth of trees. The bark of the principal stem, and of every 

 lateral branch, contains very numerous vessels, which are charged with 

 the descending true sap ; and at the juncture of the lateral branch with 

 the stem, these vessels meet each other. A kind of pedestal of albur- 

 num, the texture of which is much interwoven, is in consequence formed 

 round the base of the lateral branch, which thus becomes firmly united 

 to the tree. This pedestal, though apparently a part of the branch, de- 

 rives a large portion of the matter annually added to it from the cortical 

 vessels of the principal stem ; and thence, in the event of the death of 

 the lateral branch, it always continues to live. But it not unfrequently 

 happens, that a lateral branch forms a very acute angle with the prin- 

 cipal stem, and, in this case, the bark between them becomes compressed 

 and inactive ; no pedestal is in consequence formed, and the attachment 

 of such a branch to the stem becomes extremely feeble and insecure *. 



* The advantages which may be obtained by pruning timber trees judiciously, appear to be 

 very little known. I have endeavoured to ascertain the practicability of giving to trees such 

 forms as will render their timber more advantageously convertible to naval or other purposes. 

 The success of the experiments on small trees has been complete, and the results perfectly con- 

 sistent, in every case, with the theory I have endeavoured to support in former memoirs ; and 

 I am confident, that by appropriate management, the trunks and branches of growing trees may 

 be moulded into the various forms best adapted to the use of the ship-builder, and that the 

 growth of the trees may at the same time be rendered considerably more rapid, without any ex- 

 pense or temporary loss to the proprietor. 



