presented two mechanisms by which hopeful monsters might work. One mechanism, involving "systemic mutations", rejected the classical gene concept and is no longer considered by modern science; however, his second mechanism involved "developmental macromutations" in "rate genes" or "controlling genes" that change early development and thus cause large effects in the adult phenotype. These kinds of mutations are similar to those considered in contemporary evolutionary developmental biology. Selected bibliography Goldschmidt, R. B. (1923). The Mechanism and Physiology of Sex Determination, Methuen & Co., London. (Translated by William Dakin) Goldschmidt, R. B. (1931). Die sexuellen Zwischenstufen, Springer, Berlin. Goldschmidt, R. B. (1940). The Material Basis of Evolution, New Haven CT: Yale Univ.Press. Goldschmidt, R. B. (1960) In and Out of the Ivory Tower, Univ. of Washington Press, Seattle. References External links Stephen Jay Gould on Richard Goldschmidt Richard Goldschmidt Richard Benedict Goldschmidt: by Edward Goldsmith Guide to the Richard Goldschmidt Papers at The Bancroft Library National Academy of Sciences Biographical Memoir 1878 births Scientists from Frankfurt German emigrants to the United States 1958 deaths 20th-century German biologists Jewish American scientists American geneticists German geneticists Intersex and medicine Mutationism Internments in the United States Max Planck Institute directors