6 Krakatau 1886 and 1897 



of floating for weeks or months on sea-water without losing the 

 power of germination. 



Among the agencies concerned in the colonisation of coral islands 

 the second place may be ascribed to birds which use them as resting 

 places or visit them in search of food. They serve in various ways to 

 enrich island floras. Fruit-eating birds eject seeds which have 

 passed uninjured through their intestine. In the process of cleaning 

 and preening their plumage birds often rub off small fruits and seeds 

 attached by hooks or other contrivances to their feathers or which 

 are carried with earth or mud on their feet. 



Numerous coral islands owe their first and most widely spread 

 plants to ocean-currents and to birds. Spores and seeds of other 

 plants, as extended observations have shown, are introduced by wind 

 and occasionally by other agencies ; these quickly fill up gaps in the 

 vegetation, finding in the substratum already prepared by earlier 

 arrivals, conditions favourable for germination and subsequent 

 development. 



In the case of Krakatau, Treub expected to find phenomena 

 analogous to those already referred to as characteristic of the 

 progress of colonisation of recently formed coral islands 1 ; he wrote: 

 " Le littoral de l'ile se couvre de plantes a l'aide des graines amenees 

 par les courants oceaniques et par les oiseaux tout comme chez les 

 iles de corail. Les elements qui composent la flore de cette bande 

 littorale remonteront petit-a-petit les versants de File ; cela est 

 possible parceque la plupart de ces plantes, bien que preferant une 

 station saline, croissent vigoureusement encore eloignees de la plage 

 et a une assez grande altitude. Cependant, plus la bande v^getale 

 originaire de la plage remonte et plus sa marche se ralentira. 

 Finalement ce sera presque uniquement par rentremise des oiseaux 

 que les parties les plus elevees de File se peupleront de plantes. 

 Une fois toute l'ile couverte d'un tapis vegetal peu dense encore, le 

 terrain sera peu a peu prepare a recevoir d'autres plantes dont les 

 spores ou les graines sont amenees par le vent ou par d'autres causes." 



The actual method of plant introduction has, however, proceeded 

 along altogether different lines. In June 1886, when the island was 

 first visited by Treub, the pioneers of a new vegetation were seen from 

 the shore to the peak and he was able to establish the important fact 

 that the re-stocking of the beach and of the interior, including the 

 slopes of the cone, had been effected simultaneously, though in 

 different ways and for the most part by different plants. It was 

 shown that blue-green Algae were the first colonists on the 

 pumice and volcanic ash as also on the exposed blocks of rock in 



1 Treub, loc. cit. p. 216. 



