[15] Drummond and Cannan, Biochem. Journ., Cambridge, 1922, xvi. 53.

[16] Sisson and Broyles, Johns Hopkins Hosp. Bull., Baltimore, 1921, xxxii. 22.

[17] Hopkins, G., Journ. Physiol., Cambridge, 1912, xliv. 425.

[18] Osborne, T. B., and Mendel, L. B., Journ. Biol. Chem., 1915, xxiii. 439.

[19] Metchnikoff, The Nature of Man, English translation, 1903, p. 272.

[20] Browne, T., Pseudodoxia Epidemica, p. 396, 6th edition, 1672.

[21] Eugenius Philalethes, junior, F.R.S., Long Livers: A curious History of such Persons of both sexes who have liv’d several Ages, and Grown Young again, 1722, p. 27.

[22] Hufeland, C. W., The Art of Prolonging Life, vol. i. p. 121, English translation, 1797.

[23] Mahaffy, J. P., John Stearne, An Address at the Bicentenary of the Medical School of Trinity College, Dublin, July 1912.

[24] Bacon, R., The Cure of Old Age and Preservation of Youth, p. 63, 1683. Translated by R. Browne.