Mecanica - novella by Frank Edward Arnold The Martians Are Coming - short story by C. M. Kornbluth and Robert A. W. Lowndes and Donald A. Wollheim [as by Robert W. Lowndes] Man and the Machine: An Editorial - essay by Donald A. Wollheim Crystal World - short story by John L. Chapman The Man from the Future - short story by Donald A. Wollheim Return from M-15 - novelette by C. M. Kornbluth [as by S. D. Gottesman] Planet Leave - short story by Clifton B. Kruse The Secret Sense - short story by Isaac Asimov Worlds in Exile - poem by Frederik Pohl [as by Elton V. Andrews] The Last Viking - short story by John B. Michel [as by Hugh Raymond] Ambition - poem by Robert A. W. Lowndes [as by Wilfred Owen Morley] Purple Dandelions - short story by Donald A. Wollheim [as by Millard Verne Gordon] The Rocket - poem by Damon Knight The Reversible Revolutions - short story by C. M. Kornbluth [as by Cecil Corwin] Biped - short story by Basil Wells New Directions - essay by C. M. Kornbluth [as by Walter C. Davies]