THE following pages consist mainly of an account of an expedition to the volcanic island of Krakatau which I had an opportunity of making in the spring of 1906 in company with some other botanists. The work was originally published in the Vierteljahrsschrift der naturforschenden Gesellschaft in Zürich (Jahrgang 52, 1907): a few reprints only were available for purchase. I therefore agreed with pleasure to the proposal made to me by the Cambridge University Press to publish an English translation, particularly as Professor Seward, who carried out the preliminary negotiations, kindly offered to be the translator. I wish to express my cordial thanks to him. I would also thank the Syndics of the University Press for the care with which the volume has been produced.

Four hitherto unpublished photographs have been added to those published in the German edition. I have also taken the opportunity of making a few corrections and additions, so that the English translation may be regarded as a second edition of the original work.

Under the head of means of dispersal of fruits, seeds, and such vegetative organs as are specially adapted for reproduction, the same agencies were concerned in the colonisation of the Krakatau group, as in the colonisation of new islands in general; namely transport by birds, by wind, and by sea-currents.

The seeds and fruits of strand-plants, such as occur everywhere in the drift-zone of the coasts, are transported, almost without exception, by sea-currents. In the case of many of these their capacity for floating a considerable length of time in sea-water or in salt-solution without losing the power to germinate, has been demonstrated experimentally by Guppy, Schimper, and others. Floating capacity is not possessed in an equal degree by all strandplants. Some of them swim equally well whether freshly fallen from the tree or in a dry state, while others can be carried by water only after being dried. It is well known that such large drift-fruits as coconuts, the fruits of Gerbera Odollam, Nipa fruticans, Barringtonia, Calophyllum, and Terminalia Catappa possess the power of floating for a considerable time. Similarly small fruits and seeds float for long periods. In Guppy's experiments the seeds of Guettarda speciosa, Scaevola Koenigii, Morinda citrifolia, Tournefortia argentea and others among the strand-plants which occur on Krakatau, germinated after floating on sea-water for 40 to 53 days.

The vegetation of Krakatau and Verlaten island has in the last ten years become considerably richer, in places even luxuriant. The results of our excursion enabled us to add considerably to the plantlist of the group of islands. The present flora of Krakatau includes representatives of all divisions of the plant-kingdom : Myxomycetes, Bacteria, Algae, Fungi, Liverworts, Mosses, Ferns, Gymnosperms, and Angiosperms. The total number of species collected in the group of islands during the excursions made in 1886, 1897 and 1906 reached 137.

In the following list the species obtained on the three occasions are arranged according to families and classes, beginning with the Angiospermae dicotyledoneae. The middle column shows on which of the three islands the plants were found and when (1886, 1897 or 1906) the records were made. (Abbreviations: K. = Krakatau; V. = Verlaten island; L. = Lang island; 1 = visit in June 1886; 2 = visit in March 1897; 3 = visit in April 1906.)

The information in regard to the area of distribution of the phanerogams and vascular cryptogams is taken from the Floras and systematic works mentioned below.