The practice is disgusting, but scarcely more so than one which was prescribed a few years ago by the great physicians of Paris, who ordered their anæmic patients to drink hot blood from the slaughtered oxen at the _abattoirs_. Mr. Bonney says that the aborigines referred to willingly bleed themselves till they are weak and faint to provide the food they consider necessary for the sick person. The acacias are very abundant in Australia, in India, and Africa. This order of plants produces gum arabic and gum Senegal. The Tasmanians use the gum of _Acacia sophora_ as a food. The eucalyptus or blue-gum tree grows on the hills of Tasmania and in Victoria on the mainland of Australia; it was introduced into Europe in 1856, and has been very extensively used as a remedy for intermittent fever, influenza, and as a powerful disinfectant. “As in all similar cases,” says Stillé, “the discovery of its virtues was accidental. It is alleged that more than forty years ago the crew of a French man-of-war, having lost a number of men with ‘pernicious fever,’ put into Botany Bay, where the remaining sick were treated with eucalyptus, and rapidly recovered. It is also said that the virtues of the tree were well known to the aboriginal inhabitants.” A good illustration of the ways in which the properties of plants have been discovered, and of the relation of poisonous to harmless herbs, may be found in the practice of the American Indians in their use of the _manioc_, a large shrub producing roots somewhat like parsnips. They carefully extract the juice, which is a deadly poison, and then grate the dried roots to a fine powder, which they afterwards convert into the _cassava_ bread. How was this treatment of the root discovered? It was simply due to the fact that one species of the shrub is devoid of any poisonous property, and has only to be washed and may then be eaten with impunity. No doubt this non-poisonous root was the first which was used for food; then when the supply ran short they were driven by necessity to find out the way to use the almost identical root of the poisonous variety, which when divested of its juice is even better for food than the harmless root. Probably this was only discovered after many experiments and fatalities. “Necessity, the mother of invention,” in this as in most other things, ultimately directed the natives to the right way of dealing with this article of diet.