Plants in their Relation to Others . 501 
sidered each case carefully, and thought out what should be found if Age 
and Area were true, and then have subsequently verified it by an examina- 
tion of the facts, in all cases finding that my prediction was correct. In 
the case about to be described, for example, I first thought out the 
predictions, and then sat down to count and classify genera for six weeks, 
in perfect confidence that the result would come out in accordance with 
my anticipations — as in fact it did. The present era in the history of 
the world and its peopling with plants seems to be an era governed 
mainly by Age and Area, which has determined in broad outline the distri- 
bution of plants about the world, leaving to ecology the settlement of the 
details. 
Endemic Genera. 
In this paper I propose to attempt to extend the applicability of Age 
and Area, which hitherto has been confined to the plants of one country, 
and to species only, with occasional incidental references to genera. It will 
of course be understood that the larger the area and the number of plants 
dealt with, the less clearly does its operation show in detail, but I venture 
to hope that it will be admitted, after consideration of what is set forth 
below, that it does hold in a wide and general manner for all flowering 
plants and for the whole world. 
I shall deal principally with what are called endemic genera, confined 
to one island, one mountain chain, or other restricted locality. In one of 
my first papers ( 15 , p. 5) I pointed out an obvious deduction to be drawn 
from an acceptance of Age and Area, viz. that as a rule endemic species 
confined to small areas are in reality species ; in the earlier stages of spread- 
ing about the globe, and given time enough and absence of barriers they 
might ultimately be found covering large areas. The corollary to this, that, 
endemic genera are similarly young genera, I have left to be inferred, but 
it will be elaborated below. 
The expression of this view has met with considerable opposition, for 
it involves a break with the opinion that has for so long held the field, that 
endemic forms, whether species or genera, represent some kind of losers in 
the struggle for existence, and that the regions characterized by their 
presence are therefore to be regarded as a kind of refuges for the destitute, 
where, on account of the smaller number of species, there was less keen 
competition, and these forms had been able to survive it. It is thus 
expressed in a recent paper (8, p. 215), ‘Very many endemics owe their 
limited distribution to the circumstance that they are remnants of compara- 
tively unsuccessful types which have been exterminated elsewhere, and 
