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The Inheritance of Acquired Characters and the Provisional Hypothesis of Pangenesis

1935; University of Chicago Press; Volume: 69; Issue: 724 Linguagem: Inglês

10.1086/280617

1537-5323

Conway Zirkle,

Evolution and Science Education

1. Lamarck was neither the first nor the most distinguished biologist to believe in the inheritance of acquired characters. He merely endorsed a belief which had been generally accepted for at least 2,200 years before his time and used it to explain how evolution could have taken place. The inheritance of acquired characters had been accepted previously by Hippocrates, Aristotle, Galen (?), Roger Bacon, Jerome Cardan, Levinus Lemnius, John Ray, Michael Adanson, Jo. Fried. Blumenbach and Erasmus Darwin among others. 2. If we wish to trace the history of evolution, we should search for naturalists who lived before Lamarck and who did not believe in the inheritance of acquired characters. Brock listed but two, (1) the unknown editor of Aristotle's "Historia Animalium," and (2) the philosopher, Immanuel Kant. 3. The dogma of the immutability of species met with general acceptance only late in the eighteenth and early in the nineteenth century. Botanists from the time of Theophrastos to the time of Linnaeus believed in "degeneration." "Degeneration" did not then have its modern meaning, but was synonymous with De Vriesian mutation. Belief in degeneration was not incompatible with belief in special creation, as its effects were supposed to be neither orderly nor cumulative. 4. In order to understand what Charles Darwin meant by his provisional hypothesis of pangenesis, it is necessary that we do not give to the terms he used the meanings which they acquired during the twentieth century. Darwin's conception of the germ-plasm was not the one currently accepted. He considered the theory that the foetus was produced from an egg fertilized by a single spermatozoan but rejected it. He believed that the whole semen was a fertilizing substance and that the foetus resembled the father in proportion to the amount of semen ejaculated in coition. Furthermore, he believed in telegony and in the specific influence of semen upon the mother's body. 5. The hypothesis of pangenesis is as old as the belief in the inheritance of acquired characters. It was endorsed by Hippocrates, Democritus, Galen (?), Clement of Alexandria, Lactantius, St. Isidore of Seville, Bartholomeus Anglicus, St. Albert the Great, St. Thomas of Aquinas, Peter of Crescentius (?), Paracelsus, Jerome Cardan, Levinus Lemnius, Venette, John Ray, Buffon, Bonnet, Maupertius, von Haller and Herbert Spencer. A careful search of our available records should add a number of names to this list.