574.0822 B Cattell, Jaques, 1904- Population problems in protozoa. Experimental control of development and differentiation. Theoretical and practical aspects of — polyploidy in crop plants. The species problem. Edited by Jaques Cattell.... with a foreword by Sewall Wright... Lancaster, Pa., The Jaques Cattell press, 1941. vi p. 1 h. 293 p. ilus. 25 cm, (Anteportada: Biological simposia; a series of volumes devotes to current symposia in the field - of biology. Edited by Jaques Cattell, vol IV).