flourish in any tolerably healthy climate which is not tropical.

There are, in fact, two other causes besides climate which may prevent
immigrants from multiplying in a new country. The first of these is the
presence of microbic diseases to which the old inhabitants are wholly or
partially immune, but which find a virgin soil in the bodies of the
newcomers. The strongest example is the West Coast of Africa, of which
Miss Mary Kingsley writes: 'Yet remember, before you elect to cast your
lot with the West Coasters, that 85 per cent, of them die of fever, or
return home with their health permanently wrecked. Also remember that
there is no getting acclimatised to the Coast. There are, it is true, a
few men out there who, although they have been resident in West Africa
for years, have never had fever, but you can count them on the fingers
of one hand.' There can be no acclimatisation where the weeding out is
as drastic as this. Either the anopheles mosquito or the European must
quit. There are parts of tropical America where the natives have
actually been protected by the malaria, which keeps the white man at
arm's length. But more often the microbe is on the side of the civilised
race, killing off the natives who have not run the gauntlet of
town-life. The extreme reluctance of the barbarians who overran the
Roman Empire to settle in the towns is easily accounted for if, as is
probable, the towns killed them off whenever they attempted to live in
them. The difference is remarkable between the fate of a conquered race
which has become accustomed to town-life, and that of one which has not.
There are no 'native quarters' in the towns of any country where the
aborigines were nomads or tillers of the soil. To the North American
Indian, residence in a town is a sentence of death. The American Indians
were accustomed to none of our zymotic diseases except malaria. In the
north they were destroyed wholesale by tuberculosis; in Mexico and Peru,
where large towns existed before the conquest, they fared better. Fiji