>? 
38 KAURI ‘* GUM. 
Resin Preservative-—The preservative effect of resin seems to pk 
been exaggerated. The result of a recent research hy exer oh * 
American Lumberman of the 27th January, 1917, is that resin does little 
in excluding fungoid rots from wood. I know as a fact, after eae 
Cluster-pine for thirty years, that there are few timbers that more easily 
take fungoid rots or boring-insects; and Cluster-pine (Pinus pinaster) 
is full of resin in all its parts. It must contain two or three times the 
quantity of resin in Kauri; and, as above, yields a large part of the 
resinous products of the world. i 
Stone-pine (Pinus pinea), which I know equally well, is similarly 
resinous and similarly perishable. The Pitch-pines of tle southern 
United States have similarly a limited durability in the ground. _ 
The resin poured out by Kauri when it is cut protects the interior 
tissue mechanically; but I have no doubt that the Kauri owes its 
durability to some substance in its timber other than resin. The hard 
ervstalline resin thrown out by the Kauri tree looks at first sight 
as if it were a provision of nature enabling the tree to defend itself 
against borers and fungoid rots. But against this there is the fact 
that borers do not go into the live bark of Kauri, though they go into 
the dead, full as it is of resin. It is much more likely that Kauri resin 
is a by-praduct of the tree’s vegetative process, and is thrown off at 
every chance the tree gets of a convenient exit, such as from the bark- 
cracks in the crown formed by the swaying of the branches. 
Resin a By-product.—Resin is formed as a by-product during the 
transformation of food materials, such as starch, into woody tissue. 
(P. 10, Bull. No. 229, Forest Service, U.S.A., 1915.) 
In pine trees, where resin-formation has been studied in Europe. 
resin is formed in a small way at all times in the resin-ducts; in a 
large way after 2 tree is wounded. After a wound the resin-ducts 
enlarge and secrete a plentiful supply of resin. This takes place chiefly 
in the cambium layer and outer layers of the sapwood. These secondary 
resin-ducts are longer above than below the wound. It takes from two 
to four weeks for these ducts to form and fill with resin, It is they that 
produce the bulk of the resin of commerce. 
The French or ‘‘ light-tapping’’ system consists in making a slit 
4in. wide and about din. deep into the sapwood. The slit is gradually 
prolonged upwards for four years or more and then allowed to heal over. 
The French system does the trees no harm. 
__ The old American plan in Florida was to make great gashes in thie 
sides of the trees and a hole (the *‘ box *’), in which the turpentine col- 
lected. This killed the trees, either directly or indirectly, by disease, 
fire, and windfalls. The French system of “ light tapping * and the 
collection of the resin in cups is now being slowly introduced to America. 
Crown Deposits ——Kauri in its vegetative process—in virgin forest 
untouched by the axe—will throw off resin (‘ gum’) from cracks in the 
stem, and will form huge deposits in its crown at the juncture of the 
branches where these are swayed and strained by the wind. These crown 
deposits of Kauri “ gum’? may reach the size of a two-year-old child, and 
a “‘ gum-climber *’ may earn £10 or £12 a week getting them. They have 
been called humorously the nest-eges of forestry! 80 Ib. is claimed as 
about the maximum size for the lumps of resin produced naturally in the 
forks of living trees, and 200 lb. (some say 300 Ib.) as the maximum size 
of lumps in the ground. The discrepancy in these figures is not easy to 
account for. It is thought to be due to two or more lumps running 


