The Fruitful Facets of Galton's Polyhedron 423
Darwin felt exceptionally well and happy and that I were lucky. Mrs.
Darwin takes good care of him and will never allow him to become too
tired; she simply sends him to bed!
He has deepset eyes and in addition very protruding eyebrows, much
more than one would say from his portrait. He is tall and thin and has thin
hands, he walks slowly and uses a cane and has to stop from time to time...
His speech is very lively, merry and cordial, not too quick and very clear.
It is remarkable how soon one feels at home with people who are
friendly and cordial. What a difference with Hooker and Dyer; they were
cold and I did not care about them. But I enjoyed my visit with Darwin and
I feel much more happy these last days. It is such a pleasure to find that
somebody is really interested in you and that he cares about what you have
discovered.Third, and most importantly, Darwin also directly inspired de Vries' shift
from physiological to evolutionary and genetic studies. With fond memories in old
age, de Vries told an interviewer in 1925 (quoted in Van der Pas, 1970, p. 192): "I
was led to the study of heredity by my love for Darwin."
The source of de Vries' inspiration did not lie in the Origin of Species or the
Descent of Man, but rather in Darwin's speculation on heredity, the "provisional
hypothesis of pangenesis" as Darwin characterized his own proposal, published as
the last chapter of his two-volume 1868 treatise on Variation in Plants and
Animals Under Domestication. In his last letter to Darwin (who died six months
later), de Vries wrote, up to date as ever in commenting on Darwin's last book The
Formation of Vegetable Mold Through the Action of Worms, but also mentioning a
stronger interest in Darwin's older views on pangenesis: "After reading the first
chapter of your book, I have been attending to the habits of worms, and had the
good fortune of repeating some of your interesting observations... For some time
I have been studying the causes of the variations of animals and plants, as
described in your treatise ... I have always been especially interested in your
hypothesis of Pangenesis and have collected a series of facts in favor of it" (de
Vries to Darwin, October 15,1881).
Darwin's hypothesis of pangenesis served as a speculation that could validate
Lamarckian inheritance, a mode of transmission that Darwin deem-phasized but
did not contest. According to pangenesis, the basis of hereditary characters resides
within tiny cellular particles called gemmules. All cells produce gemmules during
growth and later life. Gemmules then migrate from somatic to germ cells, where
they collect to pass inherited characters to the next generation. The germ cells
therefore store "actual physical representatives of all the cells which have existed
during the whole life of the parent body" (Kellogg, 1907, p. 218). Since gemmules
become modified in somatic cells by conditions of life and the actions of
organisms, acquired characters can be inherited.
De Vries suggested a fundamental (and correct) modification that turned