nature; and others on the colours of animals and of plants, and on
various biological problems.[5]

"Island Life"[6] (published 1880) was begun in 1877, and occupied the
greater part of the next three years. This had been suggested by certain
necessary limitations in the writing of "The Geographical Distribution
of Animals." It is a fascinating account of the relations of islands to
continents, of their unwritten records of the distribution of plant and
animal life in the morning time of the earth, of the causes and results
of the glacial period, and of the manner of reckoning the age of the
world from geological data. It also included several new features of
natural science, and still retains an important place in scientific
literature. No better summary can be given than that by the author
himself:

In my "Geographical Distribution of Animals" I had, in the first place,
dealt with the larger groups, coming down to families and genera, but
taking no account of the various problems raised by the distribution of
particular _species_. In the next place, I had taken little account of
the various islands of the globe, excepting as forming sub-regions or
parts of sub-regions. But I had long seen the great interest and
importance of these, and especially of Darwin's great discovery of the
two classes into which they are naturally divided--oceanic and
continental islands. I had already given lectures on this subject, and
had become aware of the great interest attaching to them, and the great
light they threw upon the means of dispersal of animals and plants, as
well as upon the past changes, both physical and means of dispersal and
colonisation of animals is so connected with, and often dependent on,
that of plants, that a consideration of the latter is essential to any
broad views as to the distribution of life upon the earth, while they