MARCH, 1923.] THE ORCHID REVIEW. 73 
northern point of Prince Island it is 43 km. (27 miles).’’* A consideration 
. of the data given for ocean currents and for winds shows that these are 
abundantly sufficient to enable the comparatively short distances to be 
travelled by seeds in a viable condition. 
The five species of Orchids which have so far been recorded from 
Krakatau are: Arundina speciosa Bl., Cymbidium Finlaysonianum Lindl., 
Phajus sp., Spathoglottts plicata Bl., and Vanda Sulingit Bl. We have thus 
to account for both terrestrial and epiphytic species. Although it is probable 
that distribution by wind has been responsible for the occurrence of both 
types, it is quite possible that epiphytic species were brought indirectly by 
ocean currents. ‘‘ Inundations and high tides on the coast [of neighbour- 
ing lands] and, in the interior, swollen rivers frequently carry freshly 
uprooted trees into the sea. The earth entangled in the mass of root above 
the surface of the water may contain various seedlings and seeds . . .; 
epiphytes on the branches of the floating trees are out of reach of the injurious. 
effects of sea-water.”’ ‘‘ Tree stems and branches played an important part 
in the colonisation of Krakatau by plants and animals. Large piles of 
floating trees, stems, branches and bamboos are met with everywhere on 
the beach above high-water mark and often carried a considerable distance 
inland. Some of the animals on the island, such as the fat Iguana (Varanus 
Salvator) which suns itself in the beds of streams, may have travelled on 
floating wood, possibly also the ancestors of the numerous ants, but certainly 
plants.” It might even be that terrestial species were carried in the soil of 
the root mass of uprooted trees, but it is more likely that in each case the 
mode of distribution was the normal one met with in the group, 7.e., wind 
dispersal. The extraordinary lightness of the seeds enables them readily to 
be carried by wind, and it is probable that the fungus is carried in the form 
of sclerotia. These compact masses of mycelium, which occur practically 
in all the mycorrhizal fungi of Orchids so far studied are quite minute, and 
far lighter than the vast majority of seeds. ‘‘ Very light seeds specially 
adapted to wind dispersal, such as those of Orchids, the spores of Ferns and 
other cryptograms, are carried by the ordinary monsoon wind, while the 
‘introduction of larger and heavier seeds, some of which have no special 
flight-organs, is the result of more violent storms and cyclones.” Thus there is 
apparently not the slightest difficulty in accounting for the presence of both 
Orchid seed and fungus on Krakatau by wind dispersal. The meeting of 
the two is apparently always fortuitous wherever it occurs in chlorophyl- 
laceous Orchids. 
That this is a reasonable theory is seen from a consideration of certain 
* This and the following extracts are from “ The new flora of the volcanic island of 
Krakatau,” by A. Ernst. English translation by A. C. Seward, University Press, 
Cambridge (1908). 
