AGRICULTURAL BULLETIN 
OF THE 
STUAITS 
AND 
LLDERATED MALAY STATES. 
No. 9.] 
SEPTEMBER 1911. [Vol. X 
LATEX AND ITS RELATION TO THE LIFE OF THE 
PARENT PLANT. 
There are present in many plants chemical substances which, 
although recognised as products of activity of the living cell, neither 
in their exact mode of formation nor in their full significance are 
clearly understood. Among such substances are the alkaloids, 
glucosides, colouring matters, ethereal oils, resins and caoutchouc or 
india rubber. Many of these products are of some considerable 
economic importance. The alkaloids include strychnine, quinine, 
morphine and other drugs and violent poisons. Of the glucosides, 
which are compounds of sugars with various substances, some too 
are poisonous, yielding on decomposition prussic acid. The Lima 
bean or Java bean contains such a glucoside ; and when it is growing 
wild the percentage of prussic acid in the stems and leaves may be 
sufficiently high to be fatal to animals which feed on it. There is 
good reason to believe that such a glucoside occurs in the shoots of 
the Para rubber; and an example of its poisonous properties occurred 
several years ago, when some Para rubber trees growing in the garden 
•of the Residency in Taiping were felled because they had proved 
poisonous to horses. 
The presence of such poisonous substances in plants serves no 
■doubt to check the ravages of animals; but this can scarcely be 
regarded as a primary function. 
The colouring matters in plants serve to attract insects, whose 
.association with plants is frequently beneficial. 
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