71 



unknown, it will be fruitless to seek for the relations existing then 

 between that fauna and the flora. With some right one might suppose 

 that the number of pollen-transporting and seed-dispersing animals 

 was then very small, but suppositions are no proofs. Moreover, but 

 few reliable observations have been made in the Dutch East Indies 

 on the biological relations between flowers and fruits on the one 

 side, animals on the other side. In the publications of Knuth ') and 

 Docters van Leeuwen 2 ) on this subject a number of flower- 

 visiting insects have been recorded but often these authors give no 

 proof to have ascertained that the insects, when visiting a flower, 

 pollinated the stigma and never they seem to have examined whether 

 the formation of fruits really depended on such pollination. In a recent 

 paper on endozoic seed dispersal :! ) Docters van Leeuwen gives 

 a list of fruits and seeds found by him in the intestines of some birds 

 shot, from which he deduces that these birds disseminate the plants. 

 But fruit-eating birds need not necessarily be seed-dispersing birds ''). 

 It is clear that, generally speaking, only a very careful sowing of 

 seeds found in bird-droppings can procure the required evidence for 

 the possibility of dispersal of a given plant by birds. 



It is quite possible that in other, more fertile parts of Krakatao 

 Phanerogams predominated or, at least, there is no proof that the 

 vegetation there also was mainly composed of ferns. The statement 

 of Docters van Leeuwen 5 ): ,,ln 1886 Krakatao was furn- 

 ished in the interior with algae and ferns. A few grasses and 



,, bushes were also to be met with already here and there" does not 

 hold good for the entire island but only for the small part investigated 

 by T r e u b. Nothing is known of the vegetation of the higher ravines 

 which were the most important localities for the investigation. 



5. Hence, ferns have the task to prepare the soil for the new 

 vegetation of Phanerogams, which afterwards will cover the is/and like 

 it did before the eruption. 



This conclusion seems to be very badly founded. T r e u b appa- 

 rently supposes that, whilst the flora of the investigated part of 



l ) Knuth, Handbuch Bliitenbiologie III, 1, 2, passim. 



- 1 ) Docters van Leeuwen, Blumen und Insekten auf einer kleinen Korallen- 

 insel, Ann. |ard. Bot. Buitenzorg, XXXVII (1927), p. 1, seq. 



3 ) Docters van L. ecu wen, Kleiner Beitrag zur Kenntnis der endozoischen 

 Verbreitung einiger Hochgebirgspflanzen auf lava [Festschrift zum siebzigsten 

 Geburtstag von Karl von Goebel (1925), p. 82|. 



4 ) On this point one should consult Hans Winterstein, Handbuch der 

 vergleichenden Physiologic II (1911), p. 1198 seq. ,,Die mechanische Funktion des 

 Muskelmagens der Vogel"- 



5 ) Ann. lard. Bot- Buitenzorg XXXI (1921), p . 115, 



