58 
there are specimens bearing mite-galls. Similar material was 
collected in 1905 by Vaxetron and in 1906 by Backer, both on 
Krakatau-island. Mr. Backer also gathered leaves with galls 
of this plant on Verlaten-Hiland in 1906. 
Lately I had an opportunity of looking for galls on Krakatau 
and Verlaten-Eiland fora few days. Though | could not confine 
my attention to these galls only and had to take in the whole 
flora, I still found 19 species of plants bearing 24 varieties 
of galls. Most of these plants were not yet present on the 
islands at the time of the first expeditions. Only Nephrolepis 
hirsutula Pr. already occurred there when Professor Trevus visited 
the island in 1886. The gall-producers therefore were in relati- 
vely unfavourable circumstances for an early settlement on the 
island. Hibiscus tiliaceus, Terminalia Catappa and Wedelia biflora 
were already found by Penzie in 1897; Homalanthus populneus 
was not found till Bacxer’s second excursion in 1908. Ficus 
ribes L. and Nephrolepis biserrata Schott. were first found by me. 
As regards this latter plant, it is not impossible that she was 
already present earlier but was not noticed. The specimens I 
found were often intertwined with Nephrolepis hirsutula. The 
latter species fructified regularly, whilst the other kind bore far 
fewer fructiferous leaves. On Verlaten-Hiland, where Nephrolepis 
biserrata Schott. was very.prevalent, I did not even find a single 
soribearing frond, so that the determination of this plant could 
not even be carried out with absolute certainty. 
_ The galls I found were in most cases already generally pre- 
valent especially those whose hostplants were varieties of Nephro- 
lepis. There may be a connection between this abundance and — 
the fact that under normal conditions the spread and increase 
of a gall-producer is more or less impeded by the parasites living 
. - : : = it. There is of course a possibility that parasites of the gall- 
__- producers have crossed over to the islands, but it may be 
. oan assumed that the gall-producer preceded the parasites. 
: Coren same eT. was assumed = Taconson ‘) in peblenston 
aba R. Facons0x. De Nieuwe Prince van Krakatan. vegedeniete van den 
