154 
GARDENING AS A SCIENCE. 
An experiment performed by the renowned Du Hamel, whose researches, as 
has been correctly said, were " an anticipation of almost everything that has been 
done by the more celebrated modern phytologists," we extract from Keith's Physio- 
logical Botany, vol. 2. p. 218, as it can be compared with the Theory of Main. 
Du Hamel, we find, " undertook an inquiry in order to ascertain the origin of the 
new layer of wood ; his first experiment was that of a graft par fecusson, which 
is done by means of detaching a portion of bark from the trunk of a tree, and 
supplying its place exactly by means of a portion of bark detached from the trunk 
of a tree that shall contain a bud. In this way he grafted, (properly speaking — 
budded) the peach on the plum-tree, because the appearance of the wood which 
they respectively form is so very different, that it could be easily ascertained 
whether the new layer was produced from the stock or from the graft. Accordingly, 
at the end of four or five months after the time of grafting, the tree was cut down, 
and as the season of the flowing of the sap was past, a portion of the trunk including 
the graft was now boiled, to make it part more easily with its bark ; in the strip- 
ping of which there was found to be formed, under the graft, a thin plate of the 
wood of the peach united to the prune by its sides but not by its inner surface, 
although it had been applied to the stock as closely as possible : hence Du Hamel 
concluded, that the new layer of wood is formed from the bark and not from the 
wood of the preceding year." 
According to Mr. Main the new developments proceed from the Vital Envelope — - 
and in principle, we believe that every known fact establishes the correctness of 
his opinion. For let us presume that a small shield or piece of very juicy bark, 
with a bud and its leaf, is taken, either in April or July, from a rose-bush, and 
inserted into a vigorous and growing shoot of a China or other rose-stock, that a 
union takes place, and a shoot is produced. The fact being of constant occurrence, 
may be passed over without reflection ; but the attendant phenomena are exceedingly 
striking. The union of parts must first be effected by the junction of two moist 
surfaces so pressed together as to expel the interposed air ; hence the necessity of a 
firm, even, and compact bandage. But moist surfaces and steady pressure are not 
vital actions, neither is an extravasated juice capable of producing organization. 
It is quite clear by the investigation of cuttings placed in water, that a ring of 
granular matter is formed between the wood and the bark prior to the production 
of roots, and as this ring is to all intents perfectly organized, it must inevitably be 
developed from an organic system endowed with life. A piece of wood destitute 
of bark or bud will not germinate, and the surface of the alburnum in a stock laid 
open by the cross-cuts of the budding-knife, is nothing but wood. Therefore when- 
ever an inserted bud unites with such a surface, the union can only be effected by 
the organic granulations developed by the vitality of the bud. The bud itself 
contains the principle of life, but to enable it to grow, that portion of it which is 
called the eye must be retained, otherwise, although the shield of bark may in every 
part press against the moist alburnum, yet if the eye be gone, a minute cavity will 
