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elliptica, Benth. and D. uliginosa are known to 
contain, in their roots and stems, substances toxic 
to certain insects. 
An investigation is being carried out in the Depart- 
ment of Agriculture to ascertain the relative 
toxicities of the numerous local plants which go 
under the name of “ tuba,” and the best methods 
of preparing suitable insecticides for use against 
various classes of insect pests. This will be followed 
by experiments on the most suitable methods of 
cultivation of those plants showing a high toxicity. 
Chinese gardeners, although appreciating the value 
of Derris, grow it on a relatively small scale, mainly 
for the purpose of providing an insecticide for use 
in their vegetable gardens. Considerable quantities 
of the dried roots are used in the manufacture of 
certain proprietary insecticides; and, judging from 
enquiries received from England, it would appear 
that there is a good demand for the dried root. 
As a result of these enquiries, a number of estates 
are becoming interested in its cultivation on a 
small experimental scale in case the demand in- 
creases. The cultivation of the plant presents no 
difficulties and, as it is amenable to light shade, 
there is no reason why it should not be grown as 
a catch-crop amongst young rubber or coconuts. 
Cultivation. — Derr * may be propagated readily by 
means of stem cutting, eighteen inches long, planted 
in sandy soil. If exposed to the full sun, it is 
advisable to remove the leaves to prevent the stems 
from dying from excessive transpiration. Under 
light shade, the cuttings root earlier, often within 
six weeks from the date of planting. 
