PIERON, HENRI, _Thought and the Brain_, London: Kegan, Paul, Trench, Trübner & Co., 1927, 262 pp. Also New York: Harcourt, Brace & Co. SCHRÖDINGER, ERWIN, _What is Life?_, New York: The Macmillan Co., 1945, 90 pp. SHERRINGTON, CHARLES S., _The Brain and Its Mechanism_, Cambridge, England: The University Press, 1933, 35 pp. TILNEY, FREDERICK, _The Brain from Ape to Man_, New York: P. B. Hoeber, Inc., 1928, 2 vol., 1075 pp. WIENER, NORBERT, _Cybernetics, or Control and Communication in the Animal and the Machine_, New York: John Wiley & Sons, 1948, 194 pp. ANONYMOUS, Ten Billion Relays, _Time_, Feb. 14, 1949, p. 67. MATHEMATICAL BIOPHYSICS There has recently been another approach to the problem: How does a brain think? A group of men, many of them in and near Chicago, have been saying: “We know the properties of nerves, nerve impulses, and simple nerve networks. We know the activity of the brain. What mathematical model of nerve networks is necessary to account for the activity of the brain?” These men have used mathematics, statistics, and mathematical logic in the effort to attack this problem, and they support a _Bulletin of Mathematical Biophysics_. HOUSEHOLDER, ALSTON S., A Neural Mechanism for Discrimination, _Psychometrika_, vol. 4, no. 1, Dec. 1939, pp. 45-58. HOUSEHOLDER, ALSTON S., and Herbert D. Landahl, _Mathematical Biophysics of the Central Nervous System_, Bloomington, Ind.: Principia Press, 1945. LANDAHL, HERBERT D., Contributions to the Mathematical Biophysics of the Central Nervous System, _Bulletin of Mathematical Biophysics_, vol. 1, no. 2, June 1939, pp. 95-118. LANDAHL, HERBERT D., WARREN S. MCCULLOCH, and WALTER PITTS, A Statistical Consequence of the Logical Calculus of Nervous Nets, _Bulletin of Mathematical Biophysics_, vol. 5, no. 4, Dec. 1943, pp. 135-137. LANDAHL, HERBERT D., A Note on the Mathematical Biophysics of Central Excitation and Inhibition, _Bulletin of Mathematical Biophysics_, vol. 7, no. 4, Dec. 1945, pp. 219-221. LETTVIN, JEROME Y., and WALTER PITTS, A Mathematical Theory of the Affective Psychoses, _Bulletin of Mathematical Biophysics_, vol. 5, no. 4, Dec. 1943, pp. 139-148. MCCULLOCH, WARREN S., and WALTER PITTS, A Logical Calculus of the Ideas Immanent in Nervous Activity, _Bulletin of Mathematical Biophysics_, vol. 5, no. 4, Dec. 1943, pp. 115-133. RASHEVSKY, N., _Mathematical Biophysics_, Chicago: University of Chicago Press. Revised edition, 1948, 669 pp. RASHEVSKY, N., Mathematical Biophysics of Abstraction and Logical Thinking, _Bulletin of Mathematical Biophysics_, vol. 7, no. 3, Sept. 1945, pp. 133-148.