I am indebted to Sir William Hooker, who has, from the first, taken a deep interest in this beneficial measure, for many acts of kindness, and for his readiness to give me valuable advice and assistance; while he has rendered most essential service in successfully raising a large number of Chinchona-plants at Kew. To Dr. Weddell my thanks are due for much information most promptly and kindly supplied; and to Mr. Howard for the important suggestions and information with which he has frequently favoured me, and which no scientific man in Europe is better able to give. It is a fortunate circumstance that his invaluable and superbly illustrated work on the Chinchona genus should have been published just at the time when the Chinchonæ are about to be planted out in India and Ceylon, for from no other source could the cultivators derive so large an amount of valuable information. Mr. Howard has likewise done good service by presenting the Indian Government with a fine healthy plant of _Chinchona Uritusinga_, a species which had not previously been introduced. I take this opportunity of expressing my thanks for much assistance from Dr. Seemann, the able Editor of the 'Bonplandia;' from Mr. Dalzell, the Conservator of Forests in the Bombay Presidency; from Dr. Forbes Watson, the Reporter on the vegetable products of India, at the India Office; from Mr. Veitch, of the Royal Exotic Nursery at Chelsea; and from many kind friends both in Peru and India. I am also indebted to Mr. Alexander Smith, son of Mr. John Smith, the Curator of the Royal Botanical Gardens at Kew, for an interesting note on the principal plants employed by the natives of India on account of their real or supposed febrifugal virtues, which will be found in an Appendix. The botanical name for the plants which yield Peruvian bark was given by Linnæus, in honour of the Countess of Chinchon, who was one of the first Europeans cured by this priceless febrifuge. The word has been generally, but most erroneously, spelt _Cinchona_; and, considering that such mis-spelling is no mark of respect to the lady whose memory it is intended to preserve, while it defeats the intention of Linnæus to do her honour, I have followed the good example of Mr. Howard and the Spanish botanists in adopting the correct way of spelling the word--_Chinchona_.[1] The Counts of Chinchon, the hereditary Alcaides of the Alcazar of Segovia, do not hold so obscure a place in history as to excuse the continuance of this mis-spelling of their name.