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Darwin Correspondence Project

Fool's experiments


Caricature of Edwin Ray Lankester
Caricature of Edwin Ray Lankester
Vanity Fair, 12 January 1905

‘I love fools' experiments. I am always making them’, was one of the most interesting things the zoologist E. Ray Lankester ever heard Darwin say. ‘A great deal might be written as comment on that statement’, Lankester later recorded, but he limited himself to stating that ‘the thoughts which it suggests may be summed up by the proposition that even a wise experiment when made by a fool generally leads to a false conclusion, but that fools' experiments conducted by a genius often prove to be leaps through the dark into great discoveries.’[1]

What were Darwin’s ‘fools’ experiments’ and did they ‘prove to be leaps through the dark into great discoveries’?

The fool’s experiment that Darwin had described to Lankester involved placing under a bell jar some pollen from a male flower together with, but some distance from, an unfertilised female flower to see whether one would act in any way upon the other.[2] Darwin could hardly have expected that there would be an effect, but his testing of his own assumptions about what was possible and his openness to being surprised by nature typified his fool’s experiments. While Darwin was cautious about speculation, he was also aware of being blinkered by established knowledge that might be limited in some way. 

Darwin’s fool’s experiments, however, were more than just a challenge to accepted suppositions. They also explored unknown or mysterious aspects of the natural world and were, for Darwin, a form of wishful thinking. When considering how orchid seeds germinated, he told Joseph Hooker, ‘I have not a fact to go on, but have a notion (no, I have firm conviction!) that they are parasites in early youth on cryptogams!! Here is a fool’s notion; I have planted some on sphagnum. … It gives me great pleasure to fancy that I see radicles of orchis-seed penetrating the sphagnum; I know I shall not, & therefore shall not be disappointed.’ Nonetheless, he asked Hooker to indulge his ‘madness’ and send him some tropical mosses for his experiments.

In 1878, Darwin, deep into his investigation of the movement of embryonic roots (radicles), asked his son Francis, who was working in the state-of-the-art physiological botany laboratory run by Julius Sachs in Würzburg, to ‘try a troublesome experiment, of the class Fool.’ Sachs had been confounded that his experiments on radicles’ reaction to water contradicted those of the Polish botanist Theophil Ciesielski. Darwin wondered whether hot and dry radicles might bend towards water, but cold ones would turn away ‘with disgust’. Acknowledging that this might be too ‘good & wonderful a case & too simple an explanation of Sachs perplexity’, he nonetheless insisted that ‘it ought to be tried.’ Elimination or confirmation of the simple and obvious before proceeding to more complex explanations guided Darwin’s experimental practice in this case. 

Francis Darwin, in turn, told Darwin about ‘a real fools experiment’ that Sachs had tried: ‘he thought the green colour of cabbage catterpillars must come from chlorophyll & so he tried feeding them on etiolated leaves—but they would not turn white.’ Darwin was delighted to hear that ‘Sachs tries “fools experiments”.

Although the results of many fool’s experiments were negative, Darwin’s enthusiasm for them did not wane. This was probably because, as he explained to the Scottish botanist Alexander Stephen Wilson in 1878, ‘I have often incidentally observed curious facts when making what I call “a fool’s experiment”.’ He even encouraged other scientific investigators to undertake fool’s experiments. In 1849, he dared do no more than ‘hint’ his curiosity to Hampshire silkworm breeder Marianne Whitby concerning the possibility of producing a breed of silkworm destitute of silk. While not labelling this a fool’s experiment, Darwin did admit that in the ‘eyes of all silk-growers, this assuredly would appear the most useless of experiments ever tryed.

After reading about the chemist James Ballantyne Hannay’s attempts to produce artificial diamonds in 1881, Darwin suggested a modification to the experiment. Organic matter—the flesh of an animal mixed with vegetable matter (to give the correction proportions of carbon and nitrogen)—could be used in the experiment, because ‘such perhaps has been the source of the carbon for diamonds in their natural place.’ Darwin had long wished ‘that some one wd observe what chemical products (if any) wd result from the slow cooling of all the various elements which are present in every living organism, after they had been subjected to intense heat & pressure’, confessing to Hannay, ‘I am very fond of trying what I call “a fool’s experiment”; & such experiments, tho’ rarely successful in a direct manner, have often led to interesting side-results.

An interesting ‘side-result’ had emerged from a fool’s experiment Darwin carried out in June 1842. While staying with his in-laws at Maer Hall in Staffordshire, he had dressed some artificial flowers with fresh leaves, placed a small drop of honey in the centre of each flower, and stuck them in the ground to see whether bees would be attracted to them. Much later, in 1881, he suggested that adding ‘guiding lines’ to the nectar might attract insects, telling his neighbour Sir John Lubbock that the bees paid no attention to the artificial flowers he had ‘planted’ in 1842. Unexpectedly, it was Darwin’s three-year old son William, whose early development had been the subject of intense observation by Darwin, who had responded to the flowers and spotted the deception from across the garden at Maer. He recognised that they came from his mother’s bonnet and noticed the drop of honey in each one. This unanticipated reaction meant that the record of the experiment ended up not in Darwin’s accounts of bees but in the notebook that contained his observations on his children (DAR 210.11: 37). 

One of those children, Francis Darwin, when recalling Darwin’s love of experiment, mentioned his father’s ‘special affection for what he called “Fool’s experiments.”’ Darwin was, Francis noted, ‘probably the only man who ever attempted to solve by experiment the problem of free will and determinism.’ This involved Darwin following the pattern of many other scientific investigators and engaging in self-experimentation. Over several weeks in 1879, Darwin found that ‘with practice he could nearly always trace the “straightforward causation” of a given action, which at first seemed to have been performed “through a creative act, or by inspiration.”’ [3]

Darwin also engaged in empathetic experimentation. He attempted to experience the paranoid feelings of the insane by investing everything he met—animate or inanimate—with the ‘imaginary attributes of a spy’ and producing in himself an ‘uncanny sensation’.[4] When investigating the mental powers of earthworms, Darwin told animal intelligence expert George Romanes ‘I tried to observe what passed in my own mind when I did the work of a worm.

While Darwin designed his fool’s experiments for serious purposes, they also contained an element of playfulness and sheer delight in plotting how to trick nature or his own mind in order to reveal the processes determining the intricacies of natural phenomena. He found this method of interrogation compelling. ‘I am like a gambler,’ he declared, ‘& love a wild experiment.


[1] E. R. Lankester. 'Charles Robert Darwin'. In C. D. Warner ed., Library of the world's best literature ancient and modern. 30 vols (New York: R. S. Peale & J. A. Hill, 1896–8) 2: 4835-93, pp. 4391–2.

[2] Ibid., p. 4391.

[3] Francis Darwin, Rustic Sounds (London: John Murray, 1917), p. 19.

[4] Ibid., pp. 19–20.