Darwin was an active and engaged father during his children’s youth, involving them in his experiments and even occasionally using them as observational subjects. When his children became adults, he continued to collaborate with them; for instance his daughter Henrietta helped edit manuscripts of The Descent of Man (1872). This teaching module focuses on work done by Darwin with his son Francis on experiments for The Power of Movement in Plants (1880). The correspondence between Darwin and Francis reveals two wonderful sides of Darwin’s character: his abilities as a precise, meticulous, and inventive experimentalist, and his role as an attentive and affectionate father. Darwin’s letters to Francis mix advice on scientific matters with more practical concerns (such as the necessity of keeping proper financial records). As you read through these letters, notice that although they come from the last decade of Darwin’s life, he is still interested in his scientific questions and ideas.
Plants that move
In The Power of movement in plants Darwin continued his experiments with and observations of climbing plants. In this book Darwin provided detailed observations of the response of plants to external stimuli. Along with his other specialised books (including his books on orchids and earthworms), this monograph was intended to answer a specific set of objections to his theory of evolution by natural selection. This 1880 book sought to illustrate that evolution could account for changes in behavioral responses. In the conclusion of the book Darwin argues that gradual modifications in the development of plants in response to natural forces such as water and light could account for all botanical adaptations.
You can download the entire packet of reading materials here: Power of movement in plants source pack
Darwin, C.R. The power of movement in plants. 1880. London: John Murray.
Letter 7346– Darwin to Francis Darwin, 18 October 1870
Darwin writes to Francis to remonstrate Francis for getting himself to debt, but also sends along the money to help Francis clear his debt. Darwin cautions Francis that he knows of no one who is truly too busy to keep proper account of his finances, and further that those who land themselves in debt are in danger of compromising their character.
See images of this letter here: Letter 7346, Dar 211:6
Letter 10517– Darwin to Francis Darwin, 29 May 1876
Darwin writes to Francis to inquire about a variety of Francis’ experiments. He makes several detailed suggestions about Francis’ experimental technique.
Letter 11586– Darwin to Francis Darwin, 2 July 1878
Darwin writes to Francis to suggest that observing the cotyledons of Oats bending toward the light would do as an appropriate observation for heliotropism. He remarks that he cannot remember if such observations have been made, but that they would be worth making.
Letter 11628– Francis Darwin to Darwin, 24 July 1878
Francis writes to his father with some comments about heliotropism in molds. He remarks on the lab technician’s views on mold in walnuts. He also writes about his inability to get any labwork done, remarking that he was “too floppy to work”.
Letter 12152– Francis Darwin to Darwin, 12 July 1879
Francis writes to his father with some results from his latest experiment on movement in plants. By the time this letter was written, he and Darwin were well into the publishing stage for The Power of Movement in Plants. Francis notes that he sent a chapter on sleeping plants to their publisher.
1. Why do you think it is important to study these later, specialised books by Darwin? What do you think these books can tell us about the progress of Darwin’s theory of natural selection?
2. How do you think the collaboration between Francis Darwin and Darwin functioned? What type of fatherly advice does Darwin offer to Francis?
3. Does it change your perception of Darwin to know that he collaborated with his children and other family members? Do you think learning about his family life is important to understanding Darwin’s science?
4. What is the tone of the beginning of Chapter 9? Why do you think that Darwin and his collaborators use this mode of argumentation?
For one example of classroom activity, as performed at Harvard, click here!