88 



DISCOVERY 



leaves of coconut palms in association with slender, 

 broad-leaved trees bearing whorls of branches. 

 Isolated trees and shrubs were seen on the low-lying 

 ground which rises gradually to the base of the conical 

 mountain ; in some of the ravines half-way up the hill 

 they form patches of forest, reappearing as scattered 

 plants on the higher ridges and on the peak." 



Some of the trees had already reached a height of 

 49 ft. The beach was littered with the flotsam of the 

 waves — fruits, seeds, and branches of common Malayan 

 plants carried from Java, Sumatra, or other islands ; 

 within this drift-zone the ground was festooned with 



Fid ;,-TIll. TAl.I.r.^T TKi:i', AMi sn.Ml. lil-.NM', Vlj .i;TATIuN 



ON KKAKATAU, AI.SO PiloTuGKAl'Il-UD UY rROI'libSOR liRXST. 



By kind permission of the Cambridge University Press. 



the trailing stems of a blue-flowered tropical Con- 

 volvulus and the runners of the grass Spinifex. Above 

 the network of creeping stems rose shrubs of Hibiscus 

 and many other plants, some of them covered with the 

 thread-like stems of a parasitic Dodder. Ants, gnats, 

 and wasps were unpleasantly abundant. One of Pro- 

 fessor Ernst's photographs, reproduced in Fig. i, shows 

 a young coconut palm at the upper edge of the tide- 

 level and, to the right, a shrub festooned with the stems 

 of a Dodder {Cassytha fiUJormis). Fig. 2 affords an 

 impressive illustration of the progress made by the 

 vegetation: Professor Ernst's photograph shows the 

 tallest tree, nearly 50 ft. high, supporting the climbing 



stems of a vine, and a belt of younger trees in the 

 foreground. 



The Return of Dense Vegetation and Animal 



Life 



Dr. Leeuwen's visit to Krakatau in 1919, and in 1921 

 to the neighbouring island of Sebesi, which was almost 

 completely devastated in 1883, furnished material of 

 considerable interest. He writes of Krakatau ; " The 

 visitor who is not a naturalist, deceived by the dense 

 vegetation now clothing the island, will fail to imagine 

 and realise how at one time everything was destroyed 

 and all plants and animals on the island were annihil- 

 ated." A snake 18 ft. long was found, sixteen different 

 kinds of birds, two reptiles, thirty-two kinds of spider, 

 nearly two hundred species of insects, and other animals 

 including some land-snails. The occurrence of land- 

 snails is noteworthy as it has generally been supposed 

 that they are restricted to migration-routes on land : 

 they are apparently capable of taking a sea-voyage. 

 Their presence on an islanddoesnottherefore necessarily 

 mean either introduction by man or a former connection 

 between the island and a neighbouring continent. 

 Since 1906 the number of forest trees had considerably 

 increased ; there were many more epiphytes, that is, 

 plants which obtain a place in the sun by living on the 

 stems of trees and have no direct contact with the 

 ground ; also several additional Vascular Cryptogams — 

 plants belonging to the group which includes the ferns, 

 club-mosses, etc. The total number of vascular plants 

 so far determined from Krakatau is 259, in addition 

 to numerous lower forms of plant life. 



" The key of the past, as of the future, is to be sought 

 in the present " : by these words Huxley wished to 

 emphasise the importance of exhausting all known ex- 

 planations of phenomena before calling to our aid causes 

 which arc unfamiliar. The history of the botanical 

 colonisation of Ivrakatau gives us the means of picturing 

 similar processes at different stages of the world's 

 history. The view adopted by Darwin in the Origin 

 of Species, and now generally accepted, is that each kind 

 of plant was first produced at one place ; it had a 

 "single centre of creation." Leaving out of account 

 the large part played by man in distributing plants, 

 we must assume that the occurrence of the same species 

 in widely separated regions means that it has travelled 

 far from its original home. Darwin and other natural- 

 ists have contributed many facts based on observation 

 and experiment which throw light on the ability of 

 plants to be spread by natural agencies — by water, 

 wind, and animals. The re-clothing of Krakatau with 

 tropical vegetation from sources separated from it by 

 several miles of sea is the most striking and illuminating 

 example of the efficiency of plants as travellers and 



