1879.] 
SCARIFICATION AS A CURE FOB GUMMING IN FBUIT-TREES. 
151 
tion of swollen growths on tho lips of Lark 
w'ounds. 
The study of the changes which occur in the 
gum-affected tissues enables us to determine 
how, under its influence, the normal func¬ 
tions of the plant become deranged. Tho 
nutritive matters, laid up in reserve in the 
tissues, instead of contributing to the ali¬ 
ment and growth of the plant, go to the pro¬ 
duction of gum, and a portion of them, before 
they are transformed into it, collect in quanti¬ 
ties around the gummy centres of iiTitaticn. 
We might almost draw a comparison between 
the effects of these centres of irritation on the 
organisation of a plant, and what takes place 
when an insect punctures the bark and deposits 
its eggs among the tissues. In the latter case, 
under the influence of a specific source of ini- 
tation, a gall is formed, the tissues become 
modified in their structure, and assume a dif¬ 
ferent appearance, while the new cellules which 
are formed enclose in their interior a collection 
of alimentary substances (starch, in particular), 
which are intended no longer to supply the 
requirements of the plant, but to serve as food 
for the little parasite that is about to be hatched 
and bred among the materials. It is much the 
same with the phenomena connected with the 
formation of the wood}’ parenchyma in those 
parts of the plant which may contain the ele¬ 
ments destined to be employed in the forma¬ 
tion of gum. These phenomena appear to 
result from the poisonous activity of the centres 
of gummy irritation, in the same way as the 
production of the gall results from the deposit¬ 
ing of the insect’s egg. 
Among the remedial measures which have 
been proposed for the cure of this gum-disease, 
there is one, adds Mr. Prillieux, “ which, to my 
own knowledge, has been very effectual. This 
is the scarification of the bark. I have seen 
trees which were severely attacked by the 
disease, and unable to produce any but small 
and feeble shoots, completely restored to health, 
and sending forth fresh vigorous shoots, after 
longitudinal incisions had been made in the 
bark of the branches. The rationale is this : 
the elements necessary to the formation of new 
tissues have been transformed into gum, and 
they have to be brought back to their original 
destination. Hence a more powerful attraction 
(for the materials of the organism) must be in¬ 
troduced than that of the gummy centres. The 
wounds necessitate the production of new 
tissues; and under this very active excita¬ 
tion the matters in reserve are compelled to 
form new cells, and cease to be drawn to¬ 
wards the gummy centres.” 
M.Messager,in an article recently published in 
the Itevue llorticole (1879, p. 174), strongly re¬ 
commends the practice of making longitudinal 
incisions in the bark of trees, with a view to 
the encouragement of their growth. The pro¬ 
cess he describes as consisting of splitting the 
bark of a young tree in straight lines from top 
to bottom of tho trunk (“ a summo trunco ad 
ininm" says Pallade, who first recommended it). 
Two, three, or four of these equidistant inci¬ 
sions are made without leaving any gap, which 
would cause strangling, the depth of the inci¬ 
sions being moderate, so as not to injure the 
inner bark. The knife used must be fine and 
sharp, so as to make a clean cut, and not to 
tear the sub-epidermic tissues. 
So little is this operation known and.practised, 
that there are very few manuals which make 
the slightest allusion to it, and one might seek 
in vain for a single author who has condemned 
it. At the most, we should find in the writings of 
the last century some reservation as to its appli¬ 
cation to trees which produce gum ; but, observes 
M. Message!’, “ I advise not to stop there, for ex¬ 
perience has taught me that these reservations 
rest on imperfect observations, or purely specu¬ 
lative deductions, and that it is precisely the 
trees with gum which are the least able to do 
without the longitudinal incision. By its 
means I have often healed cases of gum-shed¬ 
ding, and I do not believe I have provoked it 
in a single instance. 
“ In the series of wounds which the gardener 
voluntarily infiicts upon his trees, there is none 
which is comparable to longitudinal incision, 
whether for safety as to its results, or for its 
harmlessness when practised without necessity 
or unseasonably; nor is there one which is 
more manifestly commanded by nature, for, 
contrary to the other wounds which are most 
frequently made to create obstacles to growth, 
this latter is an auxiliary thereto, since it 
supplies the default of certam functions tem¬ 
porarily interfered with by transplantation, sun¬ 
stroke, frost, and all other causes which conduce 
to the hardening or thickening of the bark,” 
