432 
DARWINISM 
CHAP. 
of herbivorous mammals, they ought to be most abundant 
where these are plentiful, and rare or absent where indigenous 
mammalia are wanting. Oceanic islands, as compared with 
continents, would thus furnish a crucial test of the two theories ; 
and Mr. Hemsley of Kew, who has specially studied insular 
floras, has given me some valuable information on this point. 
He says : “ There are no spiny or prickly plants in the in¬ 
digenous element of the St. Helena flora. The relatively rich 
flora of the Sandwich Isles is not absolutely without a prickly 
plant, but almost so. All the endemic genera are unarmed, 
and the endemic species of almost every other genus. Even such 
genera as Zanthoxylon, Acacia, Xylosoma, Lyciiun, and Solanum, 
of which there are many armed species in other countries, 
are only represented by unarmed species. The two endemic 
Rubi have the prickles reduced to the setaceous condition, and 
the two palms are unarmed. 
“ The flora of the Galapagos includes a number of prickly 
plants, among them several cacti (these have not been inves¬ 
tigated and may be American species), but I do not think one 
of the known endemic species of any family is prickly or 
spiny. 
“ Spiny and prickly plants are also rare in New Zealand, 
but there are the formidably armed species of wild Spaniard 
(Aciphylla), one species of Rubus, the pungent-leaved Epacridese 
and a few others.” 
Mr. J. G. Baker of Kew, who has specially studied the 
flora of Mauritius and the adjacent islands, also Avrites me on 
this point. He says: “ Taking Mauritius alone, I do not 
call to mind a single species that is a spinose endemic tree or 
shrub. If you take the Avhole group of islands (Mauritius, 
Bourbon, Seychelles, and Rodriguez), there will be about a 
dozen species, but then nine of these are palms. Leaving 
out palms, the trees and shrubs of that part of the Avorld are 
exceptionally non-spinose.” 
These are certainly remarkable facts, and quite inexplicable 
on the theory of spines being caused solely by checked vege¬ 
tative groAvth, due to Aveakness of constitution or to an arid soil 
and climate. For the Galapagos and many parts of the Sand- 
Avieh Islands are very arid, as is a considerable part of the 
North Island of New Zealand. Yet in our own moist climate 
