Mr. Pritchett left Lima on the 18th of May, 1860, and arrived in the town of Huanuco, the centre of the grey-bark region, on the 28th, where he made the necessary preparations for a journey into the neighbouring forests. On the 9th of June he set out for the mountain-range of Carpis, to the northward, where there are several species of chinchonæ. The _C. purpurea_ is very abundant; the _C. nitida_ is common on the north-east side, and on the upper part of the mountains; the _C. obovata_ is more rare; and the _C. micrantha_ and _C. Peruviana_ are both inhabitants of the lower slopes. After crossing the Carpis range, Mr. Pritchett followed the course of the river of Casapi to the village of Chinchao, and went thence to the coca estate of Casapi, at the eastern end of the valley, where it joins that of the river Huallaga, and here he was joined by his guide. [Illustration: CHINCHONA NITIDA TREES. FROM A SKETCH BY MR. PRITCHETT. Page 323] About three leagues from Casapi, and close to the Huallaga, is the mountain called San Cristoval de Cocheros (Cuchero of Pavon and Poeppig), which rises from the low land at the junction of the two rivers to a height of about 1200 feet above them, and is the centre of the bark district of Huanuco. On the northern side Mr. Pritchett found abundance of _C. micrantha_, and some trees of _C. Peruviana_; but the latter species was much more rare. They both grow to a very large size, some of them being thirty inches in diameter and seventy feet in height. The trees of _C. nitida_ were at a higher elevation. During June and July, though it was the dry season, heavy rains continued to fall from day to day; but towards the end of July the weather broke up, and the sun began to make an impression on the solid banks of cloud which filled the valleys, and then it was that, during some portion of the day, the sun penetrated to the very underwood of the forest. In the first half of August there was fine weather, with only an occasional shower. The seeds on the chinchona-trees ripened rapidly in the sunshine, and Mr. Pritchett collected them by felling the trees--a labour which was performed by Indians, whom he hired from the coca estate of Casapi. Seven large trees were cut down daily, and denuded of their capsules, for a fortnight; the drying process being carried on at the estate, where every moment of sunshine was taken advantage of. On the 13th of August he started for the coast with his collection of seeds, and half a mule-load of young chinchona-plants, which were in perfect health when placed in the Wardian cases at Lima.