EMBRYOLOGY AND EVOLUTION
that the body is supernaturally created, as some of the "preformationists" did in the eighteenth century. This old doctrine of preformation, or "evolutio," as it was called, maintained that the fully-formed but minute organism was encased within the egg or sperm, and the microscopists of the day, with poor instruments but good imagination, thought they could see the "homunculus," or little man, neatly packed away within the human germ cell. Within this homunculus in turn it was held that there must be another generation of germ cells, each containing its homunculus, and so on ad infinitum. Thus arose the doctrine of infinite encasement, or "box in box," and as the schoolmen of the Middle Ages discussed how many angels might stand on the point of a needle, so their successors of the eighteenth century discussed how many fully formed but infinitely minute generations might have been contained in the ovary of Mother Eve. These speculations reached their culmination in the works of Charles Bonnet (1748-1773), the distinguished natural philosopher of Geneva, in which he denied all new formation, all development or generation, and held that in the original creation of the progenitor of each species God created at one stroke all the individuals that would ever come from that progenitor. Thus every individual in the world was supernaturally created.
The actual study of the development of eggs forever put an end to such speculations. Caspar Frederick Wolff (1759) demonstrated that fully formed but minute organisms are not contained in germ cells; that development is not a mere unfolding of that which is already infolded, but that it consists, from inception to maturity, in an increase of complexity; and though he over-emphasized the simplicity of the germ, no one now questions that individual development everywhere consists of progress from a relatively simple
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