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) { Feb. 1. 
PROCEEDINGS OF LEARNED SOCIETIES, 
N our last we have given some account 
of the introductory lecture delivered 
at the Royal Institution by Mr. Davy: we 
mean in a stibsequent number to take up 
the subject again, and to give a full ana- 
lysis of the account of his discoveries, as 
read to the Royal Society, incorporating 
with it such experiments and observations 
as may occur to'the writer by an attend- 
ance at the interesting and important 
lectures delivered every Saturday at the 
Royal Institution in Albermarle Street. 
We shall now proceed with an wcecount 
‘of Mr. Knight’s distoveries on the incon- 
vertibility of bark into alburnum: This 
accurate observer had already found, 
that the matter, which composes the bark 
of trees, previously exists in the cells both 
of their bark and alburnum, in a fluid 
state; and that this fluid, even when extra- 
vasated, is capable of changing into a 
fulpous and cellular, and ultimately inte 
a vascular substance; the direction taken 
by the vessels being apparently depen- 
dent on the course which the descending 
flaid sap is made to take: his present 
object is, te prove that the bark, thus 
formed, always remains in the state of 
bark, and that no’part of it is evér trans- 
muted into alburnum. To ascertain this 
fact, he grafted several trees of the apple 
and crab kind, the woods of which were 
Cistinguishable from each other by their 
colours; he then transposed similar por- 
tions of bark from one tree to another, 
and bound them ‘ip closely with a cover- 
ing of cément. ‘The interior surface of 
the bark of the crab-tree presented nu- 
merous sinuosities, which corresponded 
with similar inequalities on the surface 
of the alburnum, occasioned by the for- 
mer existence of many lateral branches. 
The interior surface of the bark of the 
apple tree, as well as the external sur- 
face of the-alburnum, was, on the con- 
trary, perfectly smooth and éven. A 
“wital union soon took place- between the 
transposed pieces of bark and the albur- 
num and bark of the trees to which 
they were applied; and in the autumn 
it appeared evident, that‘a layer of albur- 
hum had been, in every instance, formed | 
beneath the transposed pieces of bark 
which were taken off; and it appear- 
ed perfectly similar to that of the other 
parts of the stock, and the direction of 
the fibrés ‘aad vessels did not, in any de- 
‘gree, correspond with those of the trans 
posed bark. 
In another experiment he scraped off 
the external surface of the alburnum in 
several small spaces, and in these spaces 
‘no union took place between the trans- 
posed bark and the alburnum of the 
stock, nor was there any alburnum de- 
posited in the abraded spaces; but the 
newly generated cortical and alburnous 
layers took a sort of curved course round 
. those spaces, and appeared to have been 
enérated by a descending fluid, which 
had divided into two currents when it 
came into contact with the spaces from 
which the surface had been seraped 
off, and to have united imniediately be- 
neath them. In each of these experi- 
ments, a uew cortical and alburnous layer 
was evidently generated, and the only 
obvious difference in the result appears 
to be, that the transposed and newly- 
generated barks formed a vital union 
‘with each other; and, if bark of any kind 
were converted into alburnum, it must 
have béen that newly generated; for, 
adds Mr. Knight, it cannot be supposed, 
that the bark of a crab-trée'was trans- 
muted into the alburnum of an apple 
tree; or, that the simuosities of the bark 
of the crab tree could have been oblite- 
rated, had. such transmutation taken 
place. f 
The next experiments were on the 
shoots of an oak coppice, which had 
been felled two years; and in these Mr. 
K.was unable to discover any thing hke 
the transmutation of bark into alburnum. 
The commencement of the alburnous 
layers in the oak ‘is distinguished by a 
‘circular row of very large tubes. These 
tubes are of course generatéd im_ the 
spring, and during their formation the 
substance, through which they pass, is 
soft and apparently gelatinous, and less 
tenacious and consistent than the sub- 
stance of the bark itself; but, if the 
fibres and vessels of the bark beeame 
those of the-alburnum, a great degree 
of similarity ought to be found in the 
organization of these substances. Mr. K. 
found no such similarity, and nothing 
at all, corresponding with the. cireular 
row of large tubes in the alburnum of 
the oak, is discovered in the bark of that 
tree. These tubes are also generated within. 
the interior suyface of the bark, which 
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