these desires and the Workers’ Educa- tional Psychology (1925), chap. 10. 13. Duane, Physical Revtew, 7, 599 (1916); 9, 568 (1916); Io, 93 and 62 of the Institute of Agriculture in 1921. But as the Modern City, 2nd ed. (Jena, 1913); H. de Vries, Species and