Book Review Biographies of Child Development: The mental growth careers of eighty-four infants and children . A ten-year study from the clinic of child development at Yale University. Part 1 by Arnold Gesell. Part 2 by Catherine S. Amatruda, Burton M. Castner and Helen Thompson. 328 pp. New York and London: Paul B. Hoeber, Inc., 1939. $3.75.