He did in fact suggest such a mechanism, called pangenesis, based on gemmules transported in the bloodstream, but subsequent experiments by Francis Galton showed that this proposed mechanism was incorrect.
32.
Darwin himself proposed a theory of inheritance of acquired characteristics which was founded on the notion of " gemmules ", which in his usage referred to the transmission of genetic information from cell to cell.
33.
Gemmules, also called plastitudes or pangenes, were assumed to be shed by the organs of the body and carried in the bloodstream to the reproductive organs where they accumulated in the germ cells or gametes.
34.
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)
35.
Some Lamarckian principles, however, have not been entirely discounted and some of Darwin's pangenesis principles ( in this regard ) do relate to heritable aspects of phenotypic plasticity, while the status of gemmules has been firmly rejected.
36.
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
37.
When conditions deteriorate, for example as temperatures drop, many freshwater species and a few marine ones produce gemmules, " survival pods " of unspecialized cells that remain dormant until conditions improve and then either form completely new sponges or recolonize the skeletons of their parents.
38.
When a gemmule germinates, the archeocytes round the outside of the cluster transform into pinacocytes, a membrane over a pore in the shell bursts, the cluster of cells slowly emerges, and most of the remaining archeocytes transform into other cell types needed to make a functioning sponge.
39.
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)
40.
:" As Darwin explained it, pangenesis was the highly abstract notion that every tissue, cell and living part of an organism produced minute, unseen gemmules ( or what he sometimes called granules or germs ) which carried inheritable characteristics and were transmitted to the offspring via the reproductive process.
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