Charles Darwin 19Some people get terribly excited by the fact that in theOriginDarwin never
used the word “evolution,” and only just squeezes out “evolved” as the last word.
This is an emotion based on ignorance. The original sense of the word “evolu-
tion” had more to do with embryonic development and only came to mean change
through time around the middle of the nineteenth century — Herbert Spencer was
much responsible for popularizing this use. People more generally used “transfor-
mation” or “transmutation” or, in Darwin’s case, “descent with modification.”
They meant “evolution” in our modern sense [Richards, 1992].
AFTER THE “ORIGIN”Anyone’s life would necessarily be a bit anticlimatical after writing and publishing
theOrigin, and so it proved for Darwin — although he was to live more than
twenty more years. He intended to go back to the beginning, writing books for
each separate chapter or section of theOrigin. In the end, Darwin completed only
one, because other ideas and projects kept coming to the fore. His first book after
theOriginwas a little work on orchids, intending to show how a topic could be
illuminated by someone who took seriously natural selection [Darwin, 1862]. Then
later on there were books on climbing plants, on insectivorous plants, and even
one on earthworms [Darwin, 1875; 1880; 1881]. A connecting thread for all of
these topics was that they could be studied by someone in his own home, someone
with the leisure and cash to run simple experiments, someone with a wide range
of correspondents who could run around and gather pertinent facts.
The one completed work of the big project was on artificial selection —The
Variation of Animals and Plants under Domestication [1868]. This was a massive
two-volume compendium of just about everything known on the subject. Its main
interest for posterity is that Darwin took the opportunity to introduce his “provi-
sional hypothesis of pangenesis.” This was his answer to the heredity problem. He
argued that all over the body there are little particles, “gemmules,” that are carried
around and down to the sex cells where they accumulate. Then in reproduction
these are passed on to the next generation, the gemmules of parents mingling in
the offspring. Note that this hypothesis centrally incorporates a Lamarckian per-
spective on generation, something to which Darwin always subscribed. A physical
change in the adult will be reflected in changes in the gemmules and thus open to
transmission across the generations. The hypothesis also assumes that generally
features in the offspring will be mixtures of features in the two parents. However,
it does leave open the possibility that effects of the gemmules from one parent
might swamp the effects of gemmules from the other parent. Moreover, and this
was a topic that fascinated Darwin, it lays open the possibility that — since the
gemmules themselves remain entire from generation to generation (any blending
effects are in the organism and not the causes) — an organism could revert to the
features of earlier generations. Some characteristic might be possessed by grand-
parent say, not the parent, but by the child. The gemmules allowed the possibility
of features skipping generations.