275 



trees and small groves, were in 1919 richer in species than the 

 higher parts. Hence it is difficult to believe that ,,on climbing 

 ,,the mountain-slopes the number of different phanerogamous 

 ,,plants becomes gradually smaller". All the slopes should be 

 carefully investigated before one ventures forth such a statement. 

 It is curious that in this paper on galls not any mention is 

 made of the gall-flowers of the 10 species of Ficus collected 

 on Krakatao. Yet it can hardly be believed that in 1919 none 

 of these species lodged gall-wasps in its figs. Possibly the gall- 

 wasps bring about fructification ') in which case they are of 

 importance for the problem of the revegetation. This matter 

 ought to have been looked into. Mr. Dammerman (See p. 277) 

 has paid some attention to gall-wasps. 



B. - Dr. W. Docters van I. ecu wen. The Galls of the Islands of the Krakatau 

 group and of the Island of Sebesy in Bull. lard. Bot. Buitenzorg, Serie III, Vol. IV 

 (1922), p. 288 seq. 



It has become a time-honoured custom to begin a paper on the 

 new flora or fauna of Krakatao with stating something like that 

 in 1883 ,,the island was completely devastated, stripped of all 

 ,,animal and vegetable life". That custom has also been 

 followed here. After having given this statement Mr. Docters 

 van Leeuwen describes an experiment, made by him on 

 Verlaten Eiland with one single sort of galls, with these words: 

 ,,1 was dwelling in a tent at the edge of the saltwater lake, 

 ,,whose salinity does not differ much from that of seawater. In 

 ,,the vicinity of this place the gall-midge gall on C/erodendron 

 ,,inerme was very prevalent. I gathered a number of twigs 

 ,,studded with galls, tied them together and then let them float 

 ,,about in the lake for a week fastened by a rope to a pole 

 ,,in the lake. A part of them was regularly above water, another 

 ,,part was regularly submerged, and was tossed about, though 

 ,,not so briskly as in a billowy sea. After this week all the galls 

 ,,were stil normal, they had remained green and the gall-creatures 

 ,,inside the galls were very much alive. 1 think I may assume 

 ,,that also other species may keep alive for a shorter or longer 

 ,,time in the sea, when enclosed in their galls. Ernst has 



*) For one of the species occurring at present on Krakatao, Ficus fulva Reinw., 

 wrongly called by Treub Ficus hirta Vahl, this eminent savant has shown [Ann. |ard. 

 Bot. Buitenzorg XVIII (1902), p. 124 seq-] that the embryo results from parthenogenetic 

 development though germinated grains of pollen may be found on the stigma, 



