Pangenesis could prevent swamping because gemmules might reproduce themselves after being released from an organ, making it possible for a few changed gemmules to "become sufficiently numerous to overpower and supplant the old [existing] gemmules" (Darwin, 1868b, p.
Darwin's half cousin Francis Galton (often called the father of eugenics) conducted a series of experiments to test the notion that gemmules moved throughout the body to transmit information to the gametes.
The effect of cadmium and mercury on gemmule
formation and gemmosclere morphology in Ephydatia fluviatilis (Porifera: Spongillidae).
Nor could he describe how gemmules
were modified, how they were "thrown off," or even what they were.
Such inferences included the notion that cells throw off gemmules, these gemmules are carried through the body, they multiply by division, and they are transmitted from generation to generation in the dormant state, finally coming together in the ovaries and testes.
Unfortunately, these proposed gemmules were nowhere to be seen.
In the fall and winter months, the larger framework of the sponge deteriorates and gemmules