high economic importance as agents of
destruction: we are learning how to pit one of them against another, so
as to leave a clear field to the farmer and the fruit grower. In this
department a leader is Professor Howard, who contributes a noteworthy
chapter on the successful fight against the pest which threatened with
ruin the orange groves of California.

To the every-day observer the most enticing field of natural history is
that in which common flowers and common insects work out their unending
co-partnery. A blossom by its scent, its beauty of tint, allures a moth
or bee and thus, in effect, is able to take flight and find a mate
across a county so as to perpetuate its race a hundred miles from home.
Our volume closes with a sketch of the singular ties which thus bind
together the fortunes of blossom and insect, so that at last the very
form of a flower may be cast in the mould of its winged ally. A word is
also spoken regarding the singular relations of late detected between
the world of vegetation and minute forms once deemed parasitic. The pea
and its kindred harbor on their rootlets certain tiny lodgers; the
tenants pay a liberal rent in the form of nitrogen compounds, a striking
interlacement of interests!

GEORGE ILES.

CONTENTS

DARWIN, CHARLES

THE ORIGIN OF SPECIES IN SUMMARY

Varieties merge gradually into species. Animals tend to
increase in geometrical ratio. Varieties diverge in consonance
with diversity of opportunity for life. In the struggle
for existence those which best accord with their surroundings
will survive and propagate their kind. Sexual selection
has put a premium on beauty. The causes which in brief
periods produce varieties, in long periods give rise to
species. Instincts, as of the hive bee, are slowly developed.
Geology supports the theory of Evolution: the changes in time
in the fossil record are gradual. Geographical distribution
lends its corroboration: in each region most of the inhabitants
in every great class are plainly related. A common ancestor
is suggested when we see the similarity of hand, wing and
fin. Embryos of birds, reptiles and fish are closely similar
and unlike adult forms. Slight changes in the course of
millions of years produce wide divergences. 3

DARWIN, CHARLES

HOW "THE ORIGIN OF SPECIES" CAME TO BE WRITTEN

During his voyage on