COLOMBO 
Added as a Supplement monihh/ to the TROPICAL AGBIGULTURISTr 
The following pages include the contents of the Magazine of the\School of 
Agriculture for June: — 
GUMMY AND RESINOUS MATTERS IN 
PLANTS. 
UMS may be defined as vegetable 
products, more or less soluble in 
cold water, but insoluble in ether, 
alcohol, and oils. They are gen- 
erally obtained amorphous and 
most of them exude spontaneously, or on punctur- 
ing the bark. The most perfect type of this class 
of substances is gum arabic or acacia, which is 
compound of a base or bases, generally lime mag. 
nesia and potash with arabic acid. Most gum s 
are similarly constituted to gum arabic wliich is 
an excretion from various species of acacia, espe- 
cially A. arabica and A. vera. The substances 
known as Barbary or Morocco gum, gum Senegal 
and Ea.st India gum are inferior commercial 
varieties of the same substance from other 
species of acacia. 
Resins may be described as vegetable sub- 
stances which are solid at the ordinary tempera- 
ture, more or less transparent, inllnmmble, 
readily fusible, which do not volatilize without 
decomposing, are insoluble in watei', but soluble 
in alcohol, and easily mixed with fatty sidistauces 
by fusion. Liebeg described them as “oxidised 
essential oils.” 
As a common example of a resin may be men- 
tioned rosin, the residue left on distilling tur- 
pentine for the oil. (ium-rosins combine the ]iio. 
perties of both gums and resins— tl\ey are part ly 
soluble in water, and partly in alcohol. A com- 
mon gum resin is assafoetida got from the root of 
certain Umbelliferae. Balsams, about which there 
has been much difference of opinion, may be 
simply described as solutions of resins in an 
essential oil. 
Turpentine may be defined as an oleo-resin, 
generally got from pines. 
Lac is a resinous substance combined with 
much colouring matter, produced by the puncture 
of the female of a small insect called the coccus 
lacca or ficus, upon the young branches of several 
tropical trees, especially the Ficus Indica, F. 
Religiosa, and Croton lacciferum. 
Now most plants contain what are known as 
intercellular spaces, that is small .spaces approxi- 
mately tringular in shape between the cells of 
tissue, occuring where the walls of cells meet. 
These spaces are formed by the unequal develop- 
ment of the common cell wall in endeavouring to 
become round, the shape which the ordinary cell 
wall inclines to in thickening. As a result of 
this a spliting occurs along the middle of the 
common wall, and thus the intercellular space is ' 
formed. These spaces generally contain air, but 
in some cases they are fille t with an exeretion, it 
may be mucillage as in cactus, oil as in orange 
and citron, or gum, re.sin, gum-resin and 
turjientine. 
.\mong the gum producing plants of Ceylon may 
be mentioned Kaju (Cashew nut), Uivul (Wood- 
aiqdo), Ilik, Imbul (Tree cotton), Ivinihiriya, 
Welan, and Na (Ironwood); gum-resins are prc- 
diiced by Rekuna, Del (Breadfruit), Kos (Jak), 
Amba (Matigol, Domba, Pol (Coconut) and 
(ioraka: resin by Hal; lac on Iveppytiya. 
