304 H. B. GUPPY, M.B., 
_Norre.—A most interesting example of the way in which vegeta- 
tion spreads has been furnished by Krakatoa, which after the great 
catastrophe of 1883, was left absolutely bare of life; the heat was 
intense, for the whole island was covered with a layer of 
cinders three feet thick. And yet already, after the short space of six 
years, the island, on being examined by an enthusiastic botanist, 
has been found to have a number of ferns flourishing on its 
unpromising soil. He writes :—‘‘these would not have obtained a 
footing had not some of the lower forms of microscopic plants 
first established themselves, and rendered the soil a_ little 
gelatinous and moist for the fern roots. The ferns in their turn 
are preparing a surface soil on which stray seeds of the higher 
plants will be able to germinate. This illustration of the process 
by which a heap of cinders is converted into a palmy South 
Sea Island is the most striking on record. The fern spores must 
have been borne on the winds.” —Kp, 
AUTHOR'S FURTHER REPLY. 
Dr. H. pz Varieny, in the Revue Scientifique for March 28, 1891, 
gives a lengthy review of my paper. He has there not only given 
the artist’s touch to my bare narrative of facts and experiments, but 
has given point and clearness to many of my imperfectly expressed 
conclusions, and for method and arrangement his review is certainly 
superior to my original paper. ‘ L’étude de M. Guppy,” thus he 
concludes the notice, “méritait mieux qu'une simple mention : 
cest une ceuvre faite avec beaucoup de soin, répondant aux 
exigences de la eritique expérimentale, et qui certainement fera 
beaucoup pour établir sur une base solide. Vhypothése d’aprés 
laquelle les courants océaniques jouent un réle important dans la 
dispersion des étres. Ce n’est méme pas aller trop loin de dire que 
M. Guppy a fait de ’hypothése une réalité, de la théorie un fait acquis.” 
The following additional experiments on the flotation of the seeds 
and seed-vessels of coral island and tropical plants have been re- 
cently made by me (the author), 
On June 8th, 1890, I put in sea-water a single bean of Entada 
scandens, a bean of another species of Entada, a seed of Casalpinia 
Bonducella, and a seed of Alewrites moluecana, all of which were 
