Gemmules
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- This article is about the mechanism for heredity. For the internal buds of freshwater sponges, see Gemmule.
In the late 1800s Charles Darwin and others proposed a mechanism of inheritance of acquired characters by means of gemmules (also called plastitudes or pangenes), which were thought to perhaps reside in the blood. This was prior to Gregor Mendel's discovery of the particulate nature of inheritance becoming common knowledge among biologists after their rediscovery in 1900.
Here are some quotes on gemmules from Charles Darwin: The Power of Place by E. Janet Browne:
Individual gemmules did not contain a complete microscopic blueprint for an entire creature in the way that Herbert Spencer or Carl von Nägeli described.' (p.276)
Pangenesis looked to him as if it might supply the answer. Darwin proposed that some limited effects from the environment might become embedded in an individual’s constitution and thus be liable to be transmitted, via the gemmules, to the offspring. (p.281)
But Darwin now wanted to include in his scheme the possibility of the inheritance of some limited acquired characteristics. Pangenesis gave him the chance to be Lamarckian without any of Lamarck’s inner strivings. As he put it, some aspects of the external environment could modify the inheritable gemmules.
In variations caused by the direct actions of changed conditions, of which several instances have been given, certain parts of the body are directly affected by the new conditions, and consequently throw off modified gemmules, which are transmitted to the offspring.18
No doubt the whole hypothesis of pangenesis was extremely complicated, he conceded. “But so are the facts.” (p.283–284)
Galton was troubled because he began the work in good faith, intending to prove Darwin right; and he praised pangenesis in Hereditary Genius in 1869. Somehow he had unintentionally proved Darwin wrong. Cautiously, he criticised his cousin’s theory, although qualifying his remarks by saying that Darwin’s gemmules (he called them “pangenes”) might be only temporary inhabitants of the blood and that his experiments could have failed to pick them up. (p.291–292)
