DARWIN, Charles, Autograph Letter Signed, to Henry Lee, dated 23 December 1871, Down House, Kent

2 leaves, each written on one side, original envelope retained, addressed in Darwin’s hand

An attractive and revealing letter from Darwin, writing to the marine biologist Henry Lee, author of Sea Monsters Unmasked (1883). Here Darwin identifies two groups of barnacle specimens, telling Lee that both are Lepas antifera, the pelagic gooseneck barnacle or smooth gooseneck barnacle. Darwin gives intricate details of the dissections he has conducted: “I have disarticulated the right-hand scutal valve in both & the umbonal teeth are plain in both”. In his Living Cirripedia (1851), Darwin had given an exceptionally detailed description of Lepas antifera, noting that in Lepas anatifera the right-hand scutum alone had an internal umbonal tooth. In Lepas australis, the scuta have umbonal teeth on both sides. Darwin goes on to discuss other minutiae of classification and offers to return the specimens by railway, adding “I have added a little spirits to the specimens, as corks leak.”

Darwin’s interest in this particular species was profound. While composing Living Cirripedia he had trained himself in micro-technique and, especially, fine dissection. This was not done simply to show off his classificatory skill: the Lepas genus had given Darwin a particular challenge, and in 1848 he sketched a small diagram and wrote the following note:

I have been much struck in Anatifera how the genus, (& I have no doubt universal, as evidenced by sub-genera) breaks up into little groups—hence those who use Dignostic character have generally to refer to only 1 [or] 2 or 3 species—So again species break up into groups of varieties Genera again in same family are united into little groups—so throughout animal Kingdom—so children even in same Family.—It is universal law.

The sketch is Darwin’s third attempt to draw the ‘tree of life’, following his famous “I think…” sketch, and the less well known 1843 diagram that is accompanied by a note reading “a tree not good simile—endless piece of seaweed dividing”. The 1848 sketch, based on his researches into Lepas, is different again, showing clear grouping of species, what we would call polytomy.

Darwin’s barnacle work is famous – or rather infamous – for occupying the period building up to the composition of On the Origin of Species. In the years after Darwin’s death, an image of him as a somewhat dilletantish theorist was cultivated by, among others, his son Francis. This, together with an urge to dramatise the composition of the Origin, led to the idea that Darwin after the Beagle Voyage Darwin had delayed the development of his theory – perhaps because it would incur the wrath of the scientific and religious establishment. In this narrative, the barnacle work is merely a distraction from Darwin’s ‘proper’ research topic, namely evolution. In fact the ‘gap’ between the Beagle and the Origin is a myth: Darwin did not ‘delay’, but instead worked carefully on his evolutionary theory, while prosecuting the barnacle classification. It is true that the latter was not a carefully planned activitiy, famously beginning with a single confusing specimen in 1846, winningly called by Darwin ‘Mr. Arthrobalanus’. But the barnacle work was important for Darwin for at least two reasons: first, it established him as a naturalist, rather than a geologist (as he had previous attempted to become), and, second, it allowed him to build up an exceptionally detailed knowledge of one single area of the natural world.

Darwin became a skilled microscopist, and turned himself from someone entirely reliant on others for close classificatory work into a master of these strange and complex creatures. He used the barnacles to explore questions of the evolution of the sexes, and also the nature of speciation itself. In the question of polytomy, explored through Lepas antifera, we see him confronting one of the central issues in evolutionary theory: does evolution itself occur more or less at random, or do the patterns of phyologenetic trees reveal some underlying ‘universal law’ of evolution itself?

Most of all, in this letter, we see Darwin as a skilled zoologist, fielding a query with care and confidence. Lee had first contacted Darwin in 1868, contributing information on sex ratios in trout, which were used in The Descent of Man. Late in 1871 Lee wrote to Darwin again, sending him information on two Lepas species, apparently in his possession. Darwin wrote back with information on the distribution of Lepas, leading to Lee’s request that Darwin examine the specimens personally. Darwin wrote back to say that he was suffering from ill health and overwork, and that he might not be able to undertake the task – but the evidence of this letter is that he went above and beyond, dissecting and reclassifying the barnacles that Lee had sent them (though perhaps not returning them, as the coda to his letter suggests).

The letter is in excellent condition, and is highly unusual in retaining the envelope, personally addressed by Darwin himself, postmarked Beckenham, 23 December 1871. The letter and envelope are housed in a very fine custom-made box, with inlaid image of Darwin, quarter-leather binding, and gilt spine titles.

Further reading:

• J. David Archibald, Aristotle’s Ladder, Darwin’s Tree: The Evolution of Visual Metaphors for Biological Order (Columbia University Press, 2014), esp. p. 86

• Kees van Putten, ‘Trees, Coral, and Seaweed: An Interpretation of Sketches Found in Darwin’s Papers’, Journal of the History of Biology 53 (2020) pp. 5–44, esp. p. 22–23