[Footnote 47: The Family and the Nation, 1909, pp. 139, 142.]
[Footnote 48: Quoted in Universe, October 22, 1921.]
[Footnote 49: Charles S. Devas, Political Economy, 2nd edition, 1901, p. 193.]
[Footnote 50: Meyrick Booth, B. Sc., Ph.D., The Hibbert Journal, October 1914, pp. 142 and 152.]
CHAPTER V
IS THERE A NATURAL LAW REGULATING THE PROPORTION OF BIRTHS AND DEATHS?
Section 1. THE THEORY OF THOMAS DOUBLEDAY REVIVED
In 1837 Thomas Doubleday [51] maintained that the rising birth-rate of his own time was closely connected with the fall in the standard of living, and his argument implied that, in order to check the excessive birth-rate, it was necessary to improve the condition of the mass of the people. Four years later he published The True Law of Population, wherein he stated that when the existence of a species is endangered—
"A corresponding effort is invariably made by Nature for its preservation and continuance by an increase of fertility, and that this especially takes place whenever such danger arises from a diminution of proper nourishment or food, so that consequently the state of depletion or the deplethoric state is favourable to fertility, and that, on the other hand, the plethoric state, or state of repletion, is unfavourable to fertility in the ratio of the intensity of each state."
By a series of experiments on plants Doubleday discovered that "whatever might be the principle of manure, an overdose of it invariably induced sterility in the plant." Although his formula is deficient in that food is selected as the one factor in environment which influences fertility, and although it may be an overstatement to claim that fertility varies in exact proportion to abundance or to scarcity, nevertheless his formula contains an important truth which literally knocks the bottom out of the whole Malthusian case.