4 22 THE STRUCTURE OF EVOLUTIONARY THEORY
that most interested de Vries. Darwin wrote books on Insectivorous Plants (1875a),
The Movement and Habits of Climbing Plants (1875b), and The Power of
Movement in Plants (1880a). In these technical studies, the two men could not
have stood closer as intellectual colleagues—even though their enduring fame
would arise elsewhere, from their disparate studies of evolution.
Second, de Vries directly courted and won Darwin's admiration and
friendship. The two men exchanged extensive correspondence (reprinted in Van
der Pas, 1970). Darwin extended much effort to help de Vries. He sent
complimentary copies of his books to de Vries, and he wrote to Asa Gray for
seeds, so that de Vries could pursue some experiments on movement in tendrils.
De Vries, for his part, repeated and extended many of Darwin's experiments on the
physiological basis of movement and insectivory in several species. For example,
de Vries wrote to Darwin on December 8, 1880:
I am very much obliged to you for your great kindness of sending me your
work on the Power of Movement in Plants ... I was especially interested by
your experiments on the movements and the curious sensitiveness of the
roots and plumules of young seedling plants, which I hope to repeat as soon
as I shall have an occasion ... I always remember the great pleasure I had in
repeating the experiments, described in your work on insectivorous
plants.... In your work, you often speak of my papers,... and I am much
indebted to you for your kind judgment of them, which will be a stimulus to
me in endeavoring to contribute my part to the advancement of science.In the summer of 1878, just before promotion to his Amsterdam
professorship, de Vries visited England and fulfilled his fondest hope of meeting
Darwin. He first called on Hooker and Thistleton-Dyer in London, but found them
cool, however kind and correct. By contrast, de Vries greatly enjoyed a
memorable, if short, visit with Darwin at Dorking, the home of Darwin's brother-
in-law, Sir Thomas H. Farrer. De Vries described this visit in a charming letter to
his fiancee on August 14, 1878:
Today I have visited Darwin; I am happy that it happened and I must say
that Darwin was so very cordial and friendly... The conversation was
quite easy; they all spoke very slowly and clearly and they gave me the
time to speak up; thus I did better in speaking English than I expected ... In
the garden there were hothouses with peaches and grapes. Darwin told me a
long story about the peaches and immediately offered me one of them; it
was delicious.
During our scientific conversation, there was the same laughing mania
as you have seen with Sachs; Sachs laughs all the time, Darwin somewhat
less but as merrily. He was very interested in what I have done lately...
He puts a footstool on a chair before he sits down on it, for he gets
headaches if he sits low—the poor soul! Mr. Farrer told me that today