d be a steady migration of plants from all
southern circumpolar countries to people the comparatively unoccupied
continent, and the southern extremity of America being considerably the
nearest, and also being the best stocked with those northern types which
have such great powers of migration and colonisation, such plants would
form the bulk of the Antarctic vegetation, and during the continuance of
the milder southern climate would occupy the whole area.

When the cold returned and the land again became ice-clad, these plants
would be crowded towards the outer margins of the Antarctic land and its
islands, and some of them would find their way across the sea to such
countries as offered on their mountain summits suitable cool stations; and
as this process of alternately receiving plants from Chile and Fuegia and
transmitting them in all directions from the central Antarctic land may
have been {523} repeated several times during the Tertiary period, we have
no difficulty in understanding the general community between the European
and Antarctic plants found in all south temperate lands. Kerguelen's Land
and The Crozets are within about the same distance from the Antarctic
continent as New Zealand and Tasmania, and we need not therefore be
surprised at finding in each of these islands some Fuegian species which
have not reached the others. Of course, there will remain difficulties of
detail, as there always must remain, so long as our knowledge of the past
changes of the earth's surface and the history of the particular plants
concerned is so imperfect. Sir Joseph Hooker notes, for example, the
curious fact that several Compositae common to three such remote localities
as the Auckland Islands, Fuegia, and Kerguelen's Land, have no pappus or
seed-down, while such as have pappus are in no case common even to two of
these islands. Without knowing the exact history and distribution of the
genera to which these plants belong it would be useless to offer any
conjecture, except that they are ancient forms which may have survived
great geographical changes, or may have some peculiar and exceptional means
of dispersion.

_Proofs of Migration by way of the Himalayas and Southern Asia._--But
although we may thus explain the presence of a considerable portion of the
European element in the floras of New Zealand and Australia, we cannot
account for the whole of it by this means, because Australia itself
contains a host of European and