56 Means of Dispersal 



different kinds of animals may be carried across water. Semon 1 

 attributes an important role to this means of distribution in the case 

 of animals in the Malay Archipelago. The possibility of certain kinds 

 of animals accomplishing a long sea voyage on floating wood has been 

 demonstrated by the observations of Guppy, who states that in the 

 course of a few years four living snakes were drifted to the Cocos 

 islands on bamboo stems and tree trunks ; he records one instance 

 of the transport of a crocodile on a large tree stem to the beach 

 of the islands. 



Tree stems and branches played an important part in the colonisa- 

 tion of Krakatau by plants and animals. Large piles of floating 

 trees, stems, branches and bamboos are met with everywhere on the 

 beach above high-water mark and often carried a considerable 

 distance inland. Some of the animals on the island, such as the fat 

 Iguana (Varcmus Salvator) which suns itself in the beds of streams, 

 may have travelled on floating wood, possibly also the ancestors 

 of the numerous ants, but certainly plants. On one of the trees 

 stranded on the beach a long time ago I found the two tubular 

 fungi Polystictus sanguineus and P. hydnoldes. Their mycelia 

 had apparently survived the sea voyage in the interior of the wood 

 and had since produced a considerable number of fructifications, 

 those of the blood-red P. sanguineus being met with a considerable 

 distance away. 



The blocks of pumice, which have been noticed since the great 

 outburst on all coasts of the Sunda Strait and farther away on the 

 beaches and covering the surface of the water in quiet bays, may, 

 as Guppy states, serve for the transport of small fruits and seeds. 

 Floating blocks of pumice and pieces lying on the beach may be 

 swept by high tides as far as the strand-forest or to the sandy ground 

 where the small fruits and sand collect in their numberless depressions 

 and holes as in the crevices of floating wood. A succeeding tide 

 carries back the pumice blocks with their freight of plants and they 

 are drifted by currents to other coasts. The germination of Pem- 

 phis acidida, Scaevola Koenigii and Triumfetta procwmbens from 

 seeds hidden in the cavities of pumice has often been observed on the 

 Cocos islands. That this means of distribution must have played a 

 more important part in the colonisation of Krakatau than in the Cocos 

 islands, is shown by the great quantity of pumice which is not only 

 piled up on all the neighbouring coasts but also covers large areas in 

 the Sunda Strait and is frequently drifted back again to its place 



1 Semon, R 1m Australischen Busch und an den Kiisten des Korallenmeeres, 

 Edit, ii., Leipzig, 1903, p. 349. 



