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was laid bare, as the first had been, and the results were simj- 
lar. The only difference observable was, that the woody mat- 
ter did not form so rapidly as it did in the first instance. At 
the expiration of three more years, a second junction had 
taken place on the pillar last laid bare. _A third was now sub- 
jected to the same experiment, the principal difference of re- 
sults in this case being, that no leaf-bud was formed on the 
lower lip. As soon as the third junction occurred, the fourth 
pillar was treated as the others had been, the growths of 
young wood becoming gradually weaker on each succeeding 
one being the only difference. 
«“ Having now detailed the way this experiment was con- 
ducted, the facts elicited enable me to deduce: 
‘Ist. That every organ in an exogenous tree may be 
thoroughly destroyed, without causing the death of the plant, 
provided they are gradually destroyed. 
“2nd. Exogenous plants, through their vital processes, 
have the power of again restoring the organs so destroyed. 
“3rd. The formative energy takes place principally above 
the wounded portion of the stem, and the newly formed tissues 
increase, for the most part, in a downward direction. 
“Though these results may, at first sight, appear to be 
little more than confirmations of the old theory of wood-for- 
mation, and even the experiment itself in some degree simi- 
lar to others which have already been made, the latter differs 
materially from any I know of, in the following particulars. 
Here the main stem of the tree was operated on, and not the 
_branches only. All the organs were destroyed, including 
pith, medullary rays, and wood. In the course of twelve 
years the stem of a large exogenous tree, measuring four feet 
nine inches in circumference, has been completely killed in a 
circular ring seven inches wide, and the organs of vitality again 
restored, without apparently affecting the health of the tree, 
which is now, while I write (June, 1851), in full bloom. The 
results, I conceive, rather than adding confirmation to the es- 
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