In Pursuit of the Gene

72 ¨ PANGENES
In the following years De Vries and Darwin exchanged half a dozen letters,
in which the two men discussed their mutual interest in plant physiology.
In 1880 Darwin sent De Vries a complimentary copy of his second book
on plant movement, The Power of Movement in Plants, in which he had adopted
many of the younger man’s ideas. De Vries acknowledged the honor that
Darwin had paid him, but by then De Vries was actively experimenting on
plant hybridization and inheritance and had mostly left behind his studies
on plant movement. Darwin’s kind judgment of his work would serve as “a
stimulus to me in endeavouring to contribute my part to the advancement
of science,” De Vries would later write. 5
The following year De Vries wrote Darwin for the final time, thanking
him for the gift of Darwin’s latest book, On the Formation of Vegetable Mould
through the Action of Worms. De Vries also mentioned that he had taken up the
subject of heredity and variation and expressed the hope that Darwin
would one day complete the long-anticipated sequel to his 1868 Variation in
Animals and Plants under Domestication about plants in the wild. Paving the way
for another collaboration, this time over the facts of heredity and variation,
De Vries wrote: “I have always been especially interested in your hypothesis
of Pangenesis and have collected a series of facts in favour of it, but I am
sure that your promised publication will contain much more evidence on
all such points, as I would for many years be able to collect.” 6
Although Darwin must have been deeply gratified to learn that someone
was still interested in Pangenesis, De Vries had arrived too late, and
Darwin, who had long since abandoned his work on pangenesis and given
up his plan to complete a sequel to Variations, died six months later in April
1882. Nonetheless, the memory of Darwin’s previous encouragement seemed
to sustain De Vries. Thirty-five years after Darwin’s death, De Vries told an
interviewer: “I was led to my study of heredity by my love for Darwin.” 7
¨ IN 1889, THE 41-YEAR-OLD De Vries published his own startlingly
original theory of heredity in a slim monograph entitled Intracellular Pangenesis.
Although the title paid homage to Darwin, and De Vries claimed to
have preserved the main ideas, when all was said and done the revised pangenesis
had little in common with Darwin’s original theory. Not only had