of forest, and where I at once obtained some of the rare birds and insects peculiar to Celebes. After about a month I returned to Macassar, and found that I could obtain a passage to the celebrated Aru Islands, where at least two species of birds of paradise are found, and which had never been visited by an English collector. This was a piece of good fortune I had not expected, and it was especially fortunate because the next six months would be wet in Celebes, while it would be the dry season in the Aru Islands. This journey was the most successful of any that I undertook, as is fully described in my book; and as no letters referring to it have been preserved, I shall say no more about it here. The illustration opposite is from a photograph of a native house in the island of Wokan, which was given me by the late Professor Moseley of the Challenger expedition, because it so closely resembles the hut in which I lived for a fortnight, and where I obtained my first King bird of paradise, that I feel sure it must be the same, especially as I saw no other like it. It is described at the beginning of chapter xxxi. of my "Malay Archipelago," and will be of interest to such of my readers as possess that work. Several months later I arrived again at Macassar, and after arranging and despatching my Aru collections, I went to an estate a few days' journey north, the property of a brother of my kind friend Mr. Mesman. I had a house built for me in a patch of forest where I lived with two Malay servants for three months making very interesting collections both of birds and insects; and I have rarely enjoyed myself so much as I did here. About the end of November I returned to Macassar, and in December embarked on the Dutch mail steamer for Amboyna, calling by the way at Timor and at Banda. At Amboyna I made the acquaintance of a German and a Hungarian doctor, both entomologists, and in a fortnight's visit to an estate in the interior surrounded by virgin forest I obtained some of the lovely birds and gorgeous insects which have made the island celebrated. The only letter I possess which indicates something of my opinions and anticipations at this period of my travels is one to Bates, dated Amboyna, January 4, 1858, from which I will make a few extracts. The larger portion is occupied with remarks on the comparative riches of our respective regions in the various families of beetles, founded on a letter I had received from him a few months before, which, though very interesting to entomologists, are not suitable for reproduction here. I then touched on the subject of my paper referred to at the end of the last chapter. "To persons who have not thought much on the subject I fear my paper on the 'Succession of Species' will not appear so clear as it does to you. That paper is, of course, merely the announcement of the theory, not its development. I have prepared the plan and written portions of a work embracing the whole subject, and have endeavoured to prove in detail what I have as yet only indicated. It was the promulgation of Forbes's theory of 'polarity' which led me to write and publish, for I was annoyed to see such an ideal absurdity put forth, when such a simple hypothesis will explain all the facts. I have been much gratified by a letter from Darwin, in which he says that he agrees with 'almost every word' of my paper. He is now preparing his great work on 'Species and Varieties,' for which he has been collecting materials twenty years. He may save me the trouble of writing more on my hypothesis, by proving that there is no difference in nature between the origin of species and of varieties; or he may give me trouble by arriving at another conclusion; but, at all events, his facts will be given for me to work upon. Your collections and my own will furnish most valuable material to illustrate and prove the universal applicability of the hypothesis. The connection between the succession of affinities and the geographical distribution of a group, worked out species by species, has never yet been shown as we shall be able to show it. "In this archipelago there are two distinct faunas rigidly circumscribed, which differ as much as do those of Africa and South America, and more than those of Europe and North America; yet there is nothing on the map or on the face of the islands to mark their limits. The boundary line passes between islands closer together than others belonging to the same group. I believe the western part to be a separated portion of continental Asia, while the eastern is a fragmentary prolongation of a former west Pacific continent. In mammalia and birds the distinction is marked by genera, families, and even orders confined to one region; in insects by a number of genera, and little groups of peculiar species, the families of insects having generally a very wide or universal distribution." This letter proves that at this time I had not the least idea of the nature of Darwin's proposed work nor of the definite conclusions he had arrived at, nor had I myself any expectation of a complete solution of the great problem to which my paper was merely the prelude. Yet less than two months later that solution flashed upon me, and to a large extent marked out a different line of work from that which I had up to this time anticipated. I finished the letter after my arrival at Ternate (January 25, 1858), and made the following observation: "If you go to the Andes I think you will be disappointed, at least in the number of species, especially of Coleoptera. My experience here is that the low grounds are much the most productive, though the mountains generally produce a few striking and brilliant species." This rather hasty generalization is, I am inclined still to think, a correct one, at all events as regards the individual collector. I doubt if there is any mountain station in the world where so many species of butterflies can be collected within a walk as at Para, or more beetles than at my station in Borneo and Bates' at Ega. Yet it may be the case that many areas of about a hundred miles square in the Andes and in the Himalayas actually contain a larger number of species than any similar area in the lowlands of the Amazon or of Borneo. In other parts of this letter I refer to the work I hoped to do myself in describing, cataloguing, and working out the distribution of my insects. I had in fact been bitten by the passion for species and their |