UNIVERSITY OF CALIFORNIA PRESS 

 BERKELEY AND LOS ANGELES 



CAMBRIDGE tTNIVERSITY PRESS 

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COPYRIGHT, 1955, BY 



THE REGENTS OF THE UNIVERSITY OF CALIFORNIA 



SECOND PRINTING, 1958 



LIBRARY OF CONGRESS CATALOG CARD NUMBER: 55-9881 

 PRINTED IN THE UNITED STATES OF AMERICA 



DESIGNED BY JOHN B. GOETZ 



