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of unconscious forces such as diseases, wars, and famines in excessive populations, have always been harried; but these blind "checks to population" have not been the only regulators of the populations as is often supposed; steadily, though invisibly, conscious control, however ineffective, has been exerted, in the form of infanticide, abortion or control of conception of some sort.

A recent monograph by Carr-Saunders^[1] developed well, and with a wealth of illustrative detail, the theme of optimum populations which all nations at all times have tended toward achieving consciously, though in the past often by the primitive and painful means of taboos, abortion and infanticide on the one hand, or by polygamy on the other. Carr-Saunders shows convincingly that the theory of Malthus has long been disproved, though it is still dinned into the ears of the uncritical public by persons insufficiently documented, and incapable of the serious application of thought. He says (p. 201): "This idea of an optimum number is one which can be developed in great detail. It is only necessary here to