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Pangenesis (Greek, ‘origin of all’), in the life sciences, is a theory for the mechanism of inheritance by which particles called gemmules (or pangenes), produced by all the cells in the body, are released into the blood-stream via which they travel to the germ cells, from which offspring develop. Darwin proposed his ‘Provisional hypothesis of pangenesis’ in 1868, based on the fairly universal pre-Mendelian view that heredity was a property of blood and that parental characteristics were blended in offspring. (Mendel had published work on heredity two years previously, showing that parental characteristics were segregated and subsequently combined, but not blended, but the importance of these findings was not realized for several decades.) The theory of pangenesis satisfied Darwin because it provided a mechanism for the inheritance of acquired characteristics, again the prevailing explanation for variation. However, experiments soon showed that Darwin\'s hypothesis was incorrect; it was modified by Hugo de Vries in 1889, linking pangenes to chromosomes in the nuclei of all cells and then by August Weismann, in 1892, who proposed that only ‘sex cells’ bore all the pangenes, somatic cells having only the information required for their differentiation. This chromosome theory allowed no mechanism for the inheritance of acquired characteristics and paved the way for the gene theory. RB
See also Darwinism; Lamarckism; Mendelism. |
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