Edward Stone (natural philosopher) piece of bark from a willow tree and was struck by its extremely bitter taste. Knowing that the bark of the Peruvian cinchona tree − from which quinine (used in the treatment of malarial fevers) is derived − has a similarly bitter taste, he surmised that the willow might also have therapeutic properties. Stone's interest in willows was due to the ancient "doctrine of signatures" – whereby the cause of a disease offers a clue to its treatment. According to Stone: "As this tree delights in a moist or wet soil, where agues chiefly abound, the general maxim that many
Cinchona la Quina" (1793) with illustrations. He proposed a Spanish expedition to search for plants of commercial value which was approved in 1783 and was continued after his death in 1808 by his nephew Sinforoso Mutis. As demand for the bark increased the trees in the forests began to be destroyed. To maintain their monopoly on cinchona bark, Peru and surrounding countries began outlawing the export of cinchona seeds and saplings beginning in the early 19th century. The Colonial European powers considered growing the plant in other tropical parts. The French mission of 1743, of which de la Condamine was member,