Mr. E. Palmer says that “the Australian aborigines possessed a considerable knowledge of indigenous plants, and their acquaintance with natural history was very accurate. They could only have obtained this knowledge by close observation and generations of experience. With the extermination of the blacks this information has completely died out, and it can only now be obtained in far-distant places like North Queensland, where the aborigines have not been killed off by contact with civilization. They have much experience in the healing virtues and properties of plants, as also of the kinds best suited for poisoning fish.”[78] Great skill is exhibited by their mode of preparing plants by fire and water and other processes, before using them as food; if partaken of in their natural state, many of them would be very deleterious, if not actually poisonous. The _Dioscorea sativa_, or karro plant, has large tubers, which are first roasted, then broken in water and strained or squeezed through fine bags made of fibre into long bark troughs, then the product is washed in many waters, the sediment is well stirred while the water is poured in; by this means the bitter principle is extracted, and a yellow fecula like hominy is produced. _Careya australis_ has a root which is used to poison fish, though its fruit is eaten uncooked by the natives. Manna is gathered from _Eucalyptus terminalis_. _Cymbidium caniculatum_ is used for dysentery and other bowel disorders. The nuts of the _Cycas media_ are very poisonous unless prepared by fire and water, and then they can be used as food. The seeds of _Entada scandens_ are only fit for eating after baking and pounding, as is the case with many other plants cleverly manipulated by the blacks. The leaves of _Ocimum sanctum_ are infused in water and drunk for sickness. A wash is made from the bruised bark of the gutta-percha tree, _Excæcaria parviflora_. The leaves of _Loranthus quandong_, the mistletoe of the _Acacia hemalophylla_, are infused in water and drunk for fevers, ague, etc.; it is doubtful whether they have any virtue, but mistletoe was once a very highly prized medicine in Europe, though now wholly obsolete. The leaves of _Melaleuca leucadendron_ are used in infusion for headache, colds, and general sickness. The _melaleuca_ is the cajeput tree, and cajeput oil is undoubtedly a valuable medicine. Stillé says, “It is of marked utility in cases of nervous vomiting, nervous dysphagia, dyspnœa, and hiccup.”[79] Externally it is valuable in nervous headache and neuralgia.