Continental and Island Life [pp. 1-29]

CONTINENTAL AND ISLAND LIFE: THEIR PRES ENT STATE AND PAST HISTORY.
HE geographical distribution of living beings in connection
with biological and geological science, has been perhaps
more fully worked out by Mr. Alfred Russel Wallace than by
any other English writer, and his recent work entitled " Island
Life" is intended as a summing up of his labors in this direction.
It thus affords a good occasion to inquire as to the present state
of knowledge on this subject, and the extent to which naturalists of Mr. Wallace's school have succeeded in solving its problems. All are now agreed that to explain the extraordinary and
often apparently anomalous distribution of animals and plants
over the surface of the earth, and the occurrence of like forms
in very distant localities, and even on islands separated by vast
stretches of ocean from one another and from the continents,
we must invoke the aid of geology. We must have reference to
those changes of climate and of elevation which have occurred
in the more recent periods of the earth's history, and must carry
with us the idea, at first not apparently very reasonable, that
living beings have existed much longer than many of the lands
which they inhabit, or at least than the present state of those
lands in reference to isolation or continental connection. To
what extent we may further require to call in the aid of varietal
or specific modification to explain the facts, may be more doubtful; and I think we shall find that a larger acquaintance with
geological facts would enable us to dispense with the aid of
hypotheses of evolution at least in so far as the establishment
of new generic and specific types is concerned.
One of the most remarkable and startling results of geological investigation, and one which must be accepted as an estab
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