After the days of Ruiz and Pavon, our chief authority on the grey barks of Huanuco is Dr. Poeppig, now a professor in Leipsic, who travelled in Chile and Peru between the years 1827 and 1832.[68] He says that, as in New Granada, the grey barks of Huanuco soon fell into discredit in the European markets, owing to the adulterations of small speculators, and that after 1815 the trade almost entirely ceased.[69] In 1830 scarcely 1250 lbs. of bark found their way from Huanuco to Lima. In the flourishing times of the Huanuco bark trade the _cascarilleros_, or bark-collectors, entered the forests in parties of ten or more, with supplies of food and tools. They penetrated for several days into the virgin forest until they came to the region of the chinchona-trees, when they built some rude huts and commenced their work. The _cateador_, or searcher, then climbed a high tree, and, with the aid of experience and sharp sight, soon discovered the _manchas_ or clumps by their dark colour, and the peculiar reflection of the light from their leaves, easily observable even in the midst of these endless expanses of forest. The _cateador_, then, with never-erring instinct, conducted the party for hours through the tangled brushwood, to the chinchona clump, using the wood-knife at every step. From a single clump they often obtained a thousand pounds of bark, which was sent up to be dried beyond the limits of the forest. All depended on the success of this operation, for the bark easily becomes mouldy and loses its colour. The _cascarilleros_ got two rials for every twenty-five pounds of green bark stripped, from the speculator, and, as they could easily strip three hundred pounds, they made two dollars a day. The bark cost the speculator about four dollars, and the price at Lima was sixteen to twenty dollars the arroba of twenty-five pounds.[70] Dr. Poeppig makes some important remarks on the supposed danger of the total extirpation of the chinchona-trees by reckless felling. Condamine and Ulloa believed that this would be the case in the Loxa forests, and Poeppig thinks that their apprehensions were well founded, because there the trees are not felled, but left standing deprived of their bark, in which case they are attacked by rot with extraordinary rapidity in tropical forests, hosts of insects penetrate to the stem, and the healthy roots become infected. But it is only necessary to observe the precaution of hewing the stem as near as possible to the root, in order to be sure of its after-growth. After six years, near Cuchero, the young stems may already be felled again; but, at higher altitudes, where the most effective chinchonas are found, it requires twenty years.[71] The _C. micrantha_ abounds in the province of Huanuco, and the bark is known as _Cascarilla provinciana_. It yields 2.7 per cent. of chinchonine, and is much sought after for the Russian market.