XIX 
DARWIN’S WORK ON THE MOVEMENTS 
OF PLANTS 
By Francis Darwin, 
Honorary Fellow of Christ's College, Cambridge. 
My father’s interest in plants was of two kinds, which may be 
roughly distinguished as Evolutionary and Physiological. Thus in 
his purely evolutionary work, for instance in The Origin of Species 
and in his book on Variation under Domestication, plants as well as 
animals served as material for his generalisations. He was largely 
dependent on the work of others for the facts used in the evolu- 
tionary work, and despised himself for belonging to the “blessed 
gang” of compilers. And he correspondingly rejoiced in the employ- 
ment of his wonderful power of observation in the physiological 
problems which occupied so much of his later life. But inasmuch as 
he felt evolution to be his life’s work, he regarded himself as something 
of an idler in observing climbing plants, insectivorous plants, orchids, 
ete. In this physiological work he was to a large extent urged on by 
his passionate desire to understand the machinery of all living things. 
But though it is true that he worked at physiological problems in 
the naturalist’s spirit of curiosity, yet there was always present to 
him the bearing of his facts on the problem of evolution. His 
interests, physiological and evolutionary, were indeed so interwoven 
that they cannot be sharply separated. Thus his original interest 
in the fertilisation of flowers was evolutionary. “I was led},” he 
says, “to attend to the cross-fertilisation of flowers by the aid of 
insects, from having come to the conclusion in my speculations 
on the origin of species, that crossing played an important part in 
keeping specific forms constant.” In the same way the value of his 
experimental work on heterostyled plants crystalised out in his mind 
into the conclusion that the product of illegitimate unions are 
equivalent to hybrids—a conclusion of the greatest interest from an 
evolutionary point of view. And again his work Cross and Self 
Fertilisation may be condensed to a point of view of great import- 
ance in reference to the meaning and origin of sexual reproduction’. 
1 Life and Letters, 1. p. 90. 
2 See Professor Goebel’s article in the present volume, p. 401. 
