Caspar Friedrich WolffBorn 18 Jan 1734; died 22 Feb 1794 at age 60. German physiologist, known as the "founder of modern embryology." In Theoria Generationis (1759) he first wrote an epigenetic theory of development: that the organs of living things take shape gradually from non-specific tissue. Wolff applied the microscope to the study of animal embryology and remarked that "the particles which constitute all animal organs in their earliest inception are little globules, which may be distinguished under a microscope." The book was ignored for half a century, as the prevailing idea was held that life begins preformed in a small body that grows larger in the same form. His name is found describing parts of the kidneys of embryos: the Wolffian body and the Wolffian ducts.