A Popular Root Of all the defences against insect enemies
that science has discovered and producers have employed none has advanced so steadily in range as the dust of the derris. Some fresh details of its peculiarly interesting history have just become known to me. Dr. Durham, who is, or should be, famous among the world's beneficent discoverers, saw some Chinese fisher- men sinking a bag in the river in order to poison or half-poison the fish. The open bag was stuffed with the root of an umbelliferous plant that grew in the neighbourhood, known generically (I think) as derris. He brought some specimens of the root home (and still possesses one piece of the original supply) and analysed it in a Cambridge laboratory. He found it to be very deadly to certain classes of land as well as water animal, but virtually harmless to mammals. The work he then did, a generation and more ago,- still stands ; and his notebooks are used by advanced students of this and kindred subjects. At this point the scientist's personal interest in the discovery ceased. The root has been on the market—, under several names—for 30 years ; and perception of its utility has grown slowly but steadily, until the last few years, when it has galloped into favour. The root has become a standard crop, especially in the Malay Peninsula, whence an immense and increasing tonnage is exported annually for the destruction of the enemies of the kindly fruits of the earth.
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