8 
QUINOLOGY OF THE EAST INDIAN PLANTATIONS. 
“ If the cambium be not injured, fresh bark seems always rapidly to grow. I have found also the quality 
improved almost as if by mossing.” Let us then in the first place seek to get a clear idea of this 
cambium, according to the most recent researches into its structure and functions.* 
The Cambium. 
If we examine the stem of a tree in winter, or during the period of complete rest, we find between 
the last-formed layer of wood and the hark a layer of cellular tissue. It was formed in the course of the 
preceding year by the influence of the nourishing sap descending between the bark and the wood. This 
matter appears at first as if in a liquid state, and constitutes that which is called the cambium, so named 
first by our countryman Grew, whose quaint, but for the time wonderfully accurate account, I subjoin. f 
By degrees this cambium becomes organized into a tissue, in which all the phenomena of the growth of the 
stem in width seem to originate. At the first return of spring the nourishing sap flows abundantly into 
this generative layer and swells up its component parts. This zone is composed of tolerably regular 
cellular tissue. Insensibly, by the progress of vegetation, a large number of these cells become longer, their 
cell-walls thicken, and soon present all the character of fibrous tissue. Coincidently with this trans- 
formation, a certain number of cells dispersed in the midst of the others increase in diameter and in length, 
their walls present transparent punctuation, and they become converted into radiated or punctuated vessels. 
These vessels and these tubes form bundles separated by a cellular tissue, which keeps its primitive form, 
and, after some time, all the interior of the generative zone becomes organized into a new woody layer, 
which adheres to and forms part of the previously-formed wood. At the same time in the portion of 
the generative layer which is in contact with the bark, a certain number of cells undergo similar trans- 
formations, assimilating them to, and preparing them to form a new portion of bark. 
The time when the sap thus begins to flow into this generative layer was chosen by MTvor as the 
most favourable for the removal of the bark ; it is then easily separated from the wood, and I found the 
bark thus gathered to be in excellent condition, and rich in alkaloids . X This flow of sap takes place at 
different periods, according to the climate, but there seems to be always a period of rest and of renewed 
spring of vegetation. 
Mode of Renewal of the Barh. 
It will thus be seen how important it is to understand thoroughly not only the conditions under which 
the renewal can be effected, but also the mode in which it takes place. On this point I have not met with 
any clearer information than is afforded by the celebrated Trench botanist M. Trecul, in several memoirs 
presented to the Academy and afterwards published in the ‘ Ann ales des Sciences Naturelles.’§ 
M. Trecul || not only furnished new proofs of the co-operation of the wood and the hark in the 
formation of new annual layers, but also demonstrated — which is very important — that each of these 
two fundamental parts of the branch, when artificially isolated, may give rise to the production either of 
wood or of bark. 
Messrs. Duhamel, Meyen, and others, had previously asserted that when a portion of the wood of the 
trunk is laid bare, and that the portion thus decorticated is so ordered as to be preserved from desiccation 
* Richard, c Nouveaux Elements de Botanique,' p. 167. 
t “ The sap, passing into the cortical body, through this (as through a Manica Hippo Gratis) is still more finely filtered. With 
which sap the cortical body being dilated as far as its tone, without a solution of continuity, will bear, and the supply of sap still 
renewed, the purest part, as most apt and ready, recedes with its due tinctures from the said cortical body to all parts of the 
lignous , — both those mixed with the bark and those lying within it. Which lignous body likewise, superinducing its own proper 
tinctures into the said sap , 'tis now to its highest preparation wrought up, and becomes (as they speak of that of an animal) 
the vegetative ros or cambium , the noblest part whereof is at last coagulated in and assimilated to the like substance with the same 
lignous body/' — ‘ The Anatomy of Plants, with an Idea of a Philosophical History of Plants,' and several other Lectures, read 
before the Royal Society, by Nehemiah Grew, M.D., F.R.S., 1682, book i. p. 15. 
t Report, 353, pp. 181, 182. § Ann. des Sc. Nat. 1853, t. xix. ; ibid. 1854. || Duchartre, ' Elements de Botanique,' p. 282. 
