curve very slightly downward in relation to the death-rate, instead of
descending with it in parallel lines.[23] This may be partly due to the
curtailment of facilities for emigration, owing to the filling up of the
new countries. For emigration does not diminish the population of the
country which the emigrants leave; it only increases its birth-rate.

We are now in a position to enumerate the causes which actually lead to
an increase in the population of a country. The first is an increase in
the amount of food produced in the country itself. If the parks and
gardens of the gentry were ploughed up or turned into allotments, a few
hundred thousands would be added to the population of the United
Kingdom, at the cost of one of the few remaining beauties which make our
country attractive to the eye. The introduction of the potato into
Ireland added several millions of squalid inhabitants to that
ill-conditioned island, and when the crop failed, large numbers of them
inflicted themselves on the United States, to the detriment of that
country. The richest countries to-day are those which produce more food
than they require, such as the United States, Canada, Australia,
Roumania, and the Argentine. (We need hardly say that throughout this
survey we are using the statistics of the years immediately before the
war.) But this state of things cannot last long, for the net increase in
such countries is invariably high, either by reason of a very high
birth-rate, as in Roumania, or because newcomers flock in to enjoy a
land of plenty. Another condition which leads to abnormally rapid
increase is found when a civilised nation conquers and administers a
backward country, introducing better methods of agriculture, and
especially irrigation and the reclamation of waste lands. The alien
Government also gives greater security, without raising the standard of
living among the natives, since the dominant race usually monopolises
the lucrative careers. In this way we are directly responsible for