The Adventure of the Lion's Mane, one of the two stories in the canon narrated by Sherlock Holmes himself. It's set on the Sussex coast, where Holmes has retired to keep bees; the location is near the fictional "little cove and village of Fulworth" whose details generally match the chalk coast between Seaford and Eastbourne (see Speculation on the location of Sherlock Holmes' Sussex retirement cottage).
Although I'm a fan of Sherlockiana, I've been a bit slow on the uptake in not realising that the natural history text quoted in the story is real: the Reverend John George Wood's 1874 Out of doors: a selection of articles on practical natural history, whose author gives a detailed account of being stung by Cyanea capillata, the lion's mane jellyfish.
One morning towards the end of July, while swimming off the Margate coast, I saw at a distance something that looked like a patch of sand, occasionally visible, and occasionally covered, as it were, by the waves, which were then running high in consequence of a lengthened gale which had not long gone down. Knowing the coast pretty well, and thinking that no sand ought to be in such a locality, I swam towards the strange object, and had got within some eight or ten yards of it before finding that it was composed of animal substance. I naturally thought that it must be the refuse of some animal that had been thrown overboard, and swam away from it, not being anxious to come in contact with so unpleasant a substance.But he describes them anyway:
While still approaching it I had noticed a slight tingling in the toes of the left foot, but as I invariably suffer from cramp in those regions while swimming, I took the ' pins-and-needles ' sensation for a symptom of the accustomed cramp, and thought nothing of it. As I swam on, however, the tingling extended further and further, and began to feel very much like the sting of a nettle. Suddenly the truth flashed across me, and I made for shore as fast as I could.
On turning round for that purpose, I raised my right arm out of the water, and found that dozens of slender and transparent threads were hanging from it, and evidently still attached to the medusa, now some forty or fifty feet away. The filaments were slight and delicate as those of a spider's web, but there the similitude ceased, for each was armed with a myriad poisoned darts that worked their way into the tissues, and affected the nervous system like the stings of wasps.
Before I reached shore the pain had become fearfully severe, and on quitting the cool waves it was absolute torture. Wherever one of the multitudinous threads had come in contact with the skin there appeared a light scarlet line, which on closer examination was resolvable into minute dots or pustules, and the sensation was much as if each dot were charged with a red-hot needle gradually making its way through the nerves. The slightest touch of the clothes was agony, and as I had to walk more than two miles before reaching my lodgings, the sufferings endured may be better imagined than described.
Severe, however, as was this pain, it was the least part of the torture inflicted by these apparently insignificant weapons. Both the respiration and the action of the heart became affected, while at short intervals sharp pangs shot through the chest, as if a bullet had passed through heart and lungs, causing me to fall as if struck by a leaden missile. Then the pulsation of the heart would cease for a time that seemed an age, and then it would give six or seven leaps, as if it would force its way through the chest. Then the lungs would refuse to act, and I stood gasping in vain for breath, as if the arm of a garotter were round my neck. Then the sharp pang would shoot through my chest, and so da capo.This meticulous reportage is typical of Wood's work as a natural history populariser. He was very prolific - see the Internet Archive for titles - and seems to have been genuinely popular. And yet it's hard in some cases to see why. His books for children - such as The Children's Picture-book of Quadrupeds: And Other Mammalia (1861), Illustrated Natural History for Young People (1882) - are extremely dry and formal, and he's obsessive about listing and defining. His Natural history rambles. Lane and field (1879) begins with a whole chapter obsessing about what constitutes a lane; and on occasion he quite puts you off going to the countryside at all. Even if you escape being stung by the Lion's Mane while swimming, there's always death waiting on the shore:
After a journey lasting, so far as my feelings went, about two years, I got to my lodgings, and instinctively sought for the salad-oil flask. As always happens under such circumstances it was empty, and I had to wait while another could be purchased. A copious friction with the oil had a sensible effect in alleviating the suffering, though when I happened to catch a glance at my own face in the mirror I hardly knew it — all white, wrinkled, and shrivelled, with cold perspiration standing in large drops over the surface.
How much brandy was administered to me I almost fear to mention, excepting to say that within half an hour I drank as much alcohol as would have intoxicated me over and over again, and yet was no more affected by it than if it had been so much fair water. Several days elapsed before I could walk with any degree of comfort, and for more than three months afterwards the shooting pang would occasionally dart through the chest.
- Medusa and her locks, Out of doors: a selection of articles on practical natural history (Rev. JG Wood, 1874, Internet Archive outdoorsaselect00woodgoog).
I make mention of this circumstance, because it is necessary to warn the enthusiastic but inexperienced naturalist, that the slimy and slippery fuci make the rock-walking exceedingly dangerous; for the masses of fuci are so heavy and thick that they veil many a deep hollow, or slightly cover many a sharp point,—in the former of which a limb may be easily broken, and by the latter a serious wound inflicted,—and there is special reason for avoiding any such mishap. Proverbially, time and tide wait for no man; and should a disabling accident occur when no one was near to help, the returning waters would bring death in their train—a death the more terrible from its slow but relentless advance.Apart from that, enjoy your day at the beach ...
- The common objects of the sea shore: Including Hints for an Aquarium (1858, Internet Archive commonobjectsse00woodgoog)
Addendum: this may not be a new observation, but I wonder if the popular name of Cyanea capillata, the lion's mane jellyfish, actually derives from the Conan Doyle story? The earliest reference to the term "lion's mane" in relation to this creature is JG Wood's 1862 account in Once a Week, Aug 23 1862, later included in the Out of Doors anthology. In that article, Wood doesn't name it as "the lion's mane", just says it looks like one:
If the bather, or shore wanderer, should happen to see, either tossing on the waves, or thrown upon the beach, a loose, roundish mass of tawny membranes and fibres, something like a very large handful of lion’s mane and silver paper, let him beware of the object, and sacrificing curiosity to discretion, give it as wide a berth as possible. For this is the fearful stinger, scientifically called Cyanea capillata, the most plentiful and most redoubtable of our venomous Medusae.At least in Google Books, I can find no references to Cyanea capillata actually being named "the Lion's Mane" pre-dating the story. The earliest occurrences I can find are in the 1940s onward:
Lowly examples are the stinging jelly fishes, one of which, Cyanea, or "lion's mane," is familiar to bathers.- Ray
- Medical Jurisprudence and Toxicology, John Glaister, 1945
6. Great Pink Jellyfish, Lion's Mane, Cyanea Capillata (Linnaeus).
- Field Book of Seashore Life, Roy Waldo Miner, 1950
One species, the lion's-mane jellyfish, Cyanea, reaches a diameter of 8 feet or more with tentacles 200 feet long.
- The underwater guide to marine life, G. Carleton Ray, Elgin Ciampi, 1958, page 99
He [Holmes] finds it is the popular name of the world's largest jelly-fish ... There has been no foul play; the victim accidentally became tangled with the lion's mane jellyfish while bathing. It is called lion's mane because in the water it bears a fair resemblance to a handful of skin and hair torn from a lion's mane.
- The Listener, Volume 60, 1958, page 410
LION'S MANE ON SUFFOLK COAST
Daily Telegraph Reporter
Fishermen along the Suffolk coast believe that large jellyfish seen by bathers are Lion's Mane jellyfish, because of their size.
- Daily Telegraph, cited in The Baker Street Journal: An Irregular Quarterly of Sherlockiana, Volumes 9-10, 1959