Veritable Scorpions from Basil
Just like your great-great-great-great-great-grandfather used to make
On the 7th of April 1864, French microbiologist Louis Pasteur gave a speech at the Sorbonne Scientific Soirée.
Today Pasteur is best known for the process that bears his name, pasteurization. But at the time, Pasteur was most famous as an opponent of spontaneous generation, the idea that living creatures commonly arise from nonliving matter. Pasteur describes the idea as: “Mightn't matter, perhaps, organize itself? Or posed differently, mightn't creatures enter the world without parents, without forebears? This is the question I seek to resolve.”
The ancients thought that snakes and frogs were spontaneously generated out of mud; that anchovies came from sea foam; and that fleas were created from dust, instead of from other fleas. There was a lot of fighting over the details, but almost everyone agreed that many animals came directly from slime.
By Pasteur’s time, biologists like Redi and Spallanzani had shown that most living things came from parents. The remaining battlefield was whether or not microbes spontaneously generated from organic matter, or if they had parents too.
Pasteur and the Irish physicist John Tyndall conducted what were eventually considered to be the conclusive experiments showing that spontaneous generation doesn’t happen, not even at the microscopic level. This is the work that Pasteur describes in his speech.
In the first couple pages of the speech, Pasteur sets the background of the theory in order to challenge it, sharing some “absurdities” of spontaneous generation’s ridiculous history. His main example is a seventeenth-century account from "the celebrated alchemical physician Van Helmont", who he quotes as saying:
Carve an indentation in a brick, fill it with crushed basil, and cover the brick with another, so that the indentation is completely sealed. Expose the two bricks to sunlight, and you will find that within a few days, fumes from the basil, acting as a leavening agent, will have transformed the vegetable matter into veritable scorpions.
The quote as it appears in Pasteur’s original French can be found here, where the instructions are rendered:
Creusez un trou dans une brique, mettez-y de l'herbe de basilic pilée, appliquez une seconde brique sur la première, de façon que le trou soit parfaitement couvert, exposez les deux briques au soleil, et au bout de quelques jours, l'odeur de basilic, agissant comme ferment, changera l'herbe en véritables scorpions.
Pasteur gives the following source for this van Helmont quote:
Les œuvres de Jean-Baptiste VAN HELMONT, traduction de Jean LE CONTE. Lyon, 1671. in-4°. Première partie. Chap. XVI : La nécessité des ferments pour les transmutations, p. 103-109.
At first I despaired of finding such an ancient document, and I assumed that I would have to rely on Pasteur’s account. But I should have known better — of course the Internet Archive has a complete copy, with the relevant passage on page 105. Here’s a screenshot:
This version is a translation by Jean Le Conte (presumably a translation from Latin; I haven’t been able to find an earlier version), and it matches an alternate French translation of these instructions that Pasteur (or perhaps his editors) offer in a footnote to the transcribed speech:
L'odeur enfermée dans la semence du basilique produit l'herbe basilique, avec l'esprit qui est dedans. Si elle se moisit en quelque endroit, elle change de nature, et produit des véritables scorpions. Ce que les incrédules pourront apprendre en mettant l'herbe contuse dans un trou qu'ils auront fait au milieu d'une brique, puis qu'ils joignent exactement une autre à celle-Iù, et qu'ils l'exposent au soleil.
You'll notice that this is actually somewhat different than the version Pasteur quoted in his speech, with some interesting differences. I’ll render it in English as best I can. Here’s my rough translation:
The scent enclosed in the basil seed produces the basil herb, from the spirit within. If the seed becomes moldy in any place, it changes its nature, and produces veritable scorpions. Unbelievers can educate themselves on the matter by putting the bruised herb in an indentation that they have made in the middle of a brick, which they join exactly with another one, and expose them to the sun.
As they say, big if true.
I don’t think it’s very likely that basil will turn into veritable scorpions, even under ideal conditions.
However, I do think it is our responsibility as scientists to attempt to replicate empirical claims from other scientists when reasonably possible. This study is easy to replicate — it won’t take me much effort to put some crushed basil between a pair of bricks and leave them in the sun for a while. I might as well try it.
It’s especially our responsibility to attempt to replicate empirical claims when the original scientist invites us to try. Here, van Helmont specifically asks skeptics to try his procedure for themselves. He really makes it sound like he has run this experiment and gotten the results he expected. We should match his freak.
Despite how crazy this all sounds, van Helmont is not a known crank. In fact, one of his studies is considered a “milestone in the history of biology”: He planted a willow tree and measured the weight of the tree, the soil, and the water he added. He found that after five years the tree had gained more than 150 pounds, with almost no change in the weight of the soil. He concluded that the plant mostly did not “eat” the soil, that most of the weight of the tree came from its water (in fact, most of the weight of a plant comes from carbon from the air). That’s the kind of attention to detail that, one would think, might prevent the recording of imaginary scorpions. He also invented the word “gas”.
If van Helmont’s procedure does work as described, that would be a pretty big deal. Re-opening the book on spontaneous generation would admittedly be a bit of a headache. But it’s the kind of headache we should be open to. If spontaneous generation is real, I wanna know. And I’m happy to spend an afternoon making the world’s most terrible caprese sandwich in an effort to find out.
Methods
Bricks 🧱
I started by collecting a number of bricks.
This was harder than expected. I discovered that the local hardware store doesn’t sell bricks, and also discovered that bricks weigh a lot more than you might think, even for bricks. In the end I was able to collect five bricks from vacant lots. This made for two pairs of bricks, plus a backup.
The instructions call for the bricks to have “an indentation”. I decided to try two different kinds.
For the first brick (left), I hollowed out an indentation by repeatedly hitting the face of the brick with a small CRAFTSMAN® claw hammer (bottom center).
I also found a Stiles and Hart Brick, which comes with a built-in indentation (right).
Basil 🌿
On Monday, June 24, I got two kinds of basil from the local Stop & Shop.
The first was Nature's Promise Organic Basil in a flat plastic container (left). The other was Goodness Gardens Fresh Hydroponic Basil (right). I figured that these two provided a decent amount of diversity, in case the kind or quality of basil makes a difference for producing scorpions.
My basil obtained, I then had to decide how to prepare it.
Pasteur uses the word “pilée”, from the verb piler, usually translated as “to crush”, so this would be “crushed basil” or possibly “smashed basil” (compare glace pilée, crushed or shaved ice).
Jean Le Conte uses the word “contuse”. Confusingly, this does not appear to be used in modern French. However, the English version of this term comes from Latin contundo, meaning beat, pound, or bruise. Le Conte likely got the word from this same root, so a reasonable translation might be “bruised” or “pounded”.
I accomplished this crushing/bruising by putting each type of basil inside a separate ramekin, along with a small amount of water, and crushing it with a spoon. As above, the Nature's Promise Organic Basil is on the left and the Goodness Gardens Fresh Hydroponic Basil is on the right.
I then put each basil mixture inside a brick, the Nature's Promise Organic Basil inside the hand-hollowed brick and the Goodness Gardens Fresh Hydroponic Basil inside the Stiles and Hart Brick.
Once the basil pilée/contuse was inside the bricks, I covered each brick with a brick of equivalent size, completely trapping the basil within the indentations, and I set these brick configurations outside in direct summer sunlight.
Sunlight ☀️
Sunlight was easy enough to get, as the next several days were to be sunny. So the main question at this point was how long it might take to turn the basil into scorpions.
Pasteur’s translation suggests “within a few days” / “au bout de quelques jours”, while Le Conte’s translation doesn’t seem to suggest anything about how long this should take, saying simply, “expose them to the sun” / “qu'ils l'exposent au soleil”. However, he does suggest that the basil needs to become moldy (moisir).
Based on this, I planned to leave the bricks in the sunlight for 3-5 days before very carefully opening them up and checking for scorpions. If they failed to produce scorpions in that time, I might leave them for longer, especially if the basil was not visibly moldy by that point.
Results
I put the basil between the bricks on Monday, and first pulled them out on Saturday.
I invited my friend Tim over to witness the results, in case my findings were to be the kind that might provoke disbelief. I also gave him a small tupperware vessel in which to contain the scorpions for further study, should any appear.
However, when I opened the bricks, there were no scorpions. The basil in the brick on the left was still moist, while the basil on the right was dry and crispy.
While there were no scorpions to be found, I noticed that the basil had not moldered yet, at least not in the sense of becoming literally moldy. This seemed like it might be a problem, since the Le Conte translation implies that it was the moldering of the basil that led to the production of scorpions (“Si elle se moisit en quelque endroit, elle change de nature…”). So I covered the bricks back up with the bricks and put them back in the sunshine.
On the following Wednesday, after more than a week in the sun, I opened them once more. There were still no scorpions, and the basil had not visibly changed. While the basil had still not moldered, I decided to end the study here.
Discussion
I was ultimately unable to reproduce the results van Helmont described, but I have a few guesses about why.
Instructions Unclear, Scorpions stuck in Brick
The instructions passed down to us from Pasteur and Le Conte are pretty sparse, so there might have been any number of errors in my method. I could have used the wrong kind of basil, the wrong kind of bricks, even the wrong kind of sunlight. A lot has changed since the 17th century. Maybe you need to use bricks made from clay from the right part of Belgium. Maybe the variety of basil that turns into scorpions has gone extinct. Maybe I just needed to leave them out in the sunlight for longer.
There are even some signs in the instructions that this kind of detail might be missing. The French is ambiguous, but suggests that the “semence” of the basil is what changes and produces scorpions. Now semence can be translated figuratively as “essence”, but it can also be translated more literally as “seed". So another interpretation is that basil stems and leaves don’t produce scorpions, and that I should have sealed up basil seeds between two bricks, and that their moldering might have successfully produced veritable scorpions.
But if special conditions are required to produce scorpions, it’s van Helmont’s responsibility to tell us. He doesn’t say anything about how you need to use this kind of brick or that kind of basil to get things right. He doesn’t even say anything about how long you need to leave them out in the sunlight. Just “[put] the bruised herb in an indentation … made in the middle of a brick … [join it] exactly with another one, and expose them to the sun.”
This implies that van Helmont thinks this scorpion generation recipe is pretty robust. If the type of brick or variety of basil really mattered, he would have included that in the instructions. Since he didn’t say anything about them, he’s suggesting that you can use any bricks or basil, leave them in the sun for however long, and it should still work. Our responsibility is to take other scientists’ writing seriously.
Translation Errors
All I have to work with are French translations of the original text, which was probably in Latin. On top of that, I have to translate the French into English. This means there are at least two places where translation errors might sneak in. The French looks pretty straightforward to me, but there might be all kinds of subtleties hidden in the jargon.
The two French translations don’t even agree with each other, and it’s not clear why. Are they two independent translations from the original source? Or is Pasteur paraphrasing Le Conte in his speech, not quoting him directly? All these questions are hard to settle without the original source. If anyone can find van Helmont’s original instructions, please let me know.
Scorpions from Elsewhere
A final possibility is that Pasteur was right, and basil doesn’t turn into scorpions under any conditions, that scorpions only ever come from other scorpions. If this is true, we have to wonder why van Helmont made such a wildly inaccurate claim.
It certainly could be the case that he was simply lying. But this doesn’t seem very likely — van Helmont was otherwise a respected scientist and intellectual. If we can’t trust the man who invented the word “gas”, who can we trust?
It’s also possible that van Helmont never tried this design for himself, and was relying on someone else’s report. This also seems unlikely, especially given that he suggests “unbelievers” try it at home. That really makes it sound like he’s seen these scorpions with his own eyes.
You might also think that van Helmont did try the design, and did find scorpions between the bricks — they just came from outside the bricks, rather than being spontaneously generated from basil. Perhaps there was some basil crushed into a brick, and van Helmont noticed a few days later that scorpions had found their way inside. Maybe the bricks were porous and there were already scorpion eggs coincidentally in the brick, or maybe moldy basil attracted a bunch of little bugs, which attracted the scorpions.
The problem with this idea is that van Helmont is from the temperate, northern European nation of Belgium. His Wikipedia page does say that he spent some time in other parts of Europe, like Switzerland, Italy, France, Germany, and England, but none of these places are famous for their scorpions. Maybe he saw a demonstration abroad, but more likely he tried the procedure at home in Brussels, and I don’t expect there are scorpions crawling around the gardens of northern Europe.
Or at least, that’s what I thought at first, before discovering Euscorpius italicus, the Italian small wood-scorpion. Despite its name, E. italicus is found in countries across Europe — including very occasionally in Belgium. This paper from 2002 mentions eight sightings of Euscorpius scorpions “found in houses or in surrounding areas” around Belgium. And the Global Biodiversity Information Facility provides this map of Euscorpius italicus observations, including two near Brussels:
Wikipedia further says, “this species can be found in a variety of warm habitats, such as ruins, buildings, under household furnishings, and in crevices of walls. It is most often encountered near humans or places that humans have considerably changed. In nature, it hides under rocks.” They are quite small, sometimes smaller than a housekey. That definitely sounds like the kind of scorpion that might hide between two bricks.
Or van Helmont might have encountered Tetratrichobothrius flavicaudis, the European yellow-tailed scorpion. T. flavicaudis is even less bothered by the cold than E. italicus, having made its way as far north as the British isles, where there is now a colony of around 10,000 scorpions. As with E. italicus, they can be quite small — see this photo from a very confused UK redditor. Wikipedia says, “in the UK, the scorpion occupies cracks and holes in walls where the mortar pointing has crumbled away.” I was even able to find this photograph of a T. flavicaudis happily chilling in the gap between two bricks!
If I have any Belgian or UK readers, it might be interesting to replicate this procedure in your back garden — set up some basil and bricks, and see if they attract your local scorpions.
Assuming the scorpions are finding their way in from the outside, and not being created directly from the spirit of the basil, you should be able to prevent their appearance by putting the bricks inside some kind of tupperware, or other scorpion-proof container. Comparing the rate of scorpion appearance between bricks inside a sealed container and bricks sitting around outside might provide a definitive test of where van Helmont’s scorpions were coming from, putting this question to rest once and for all.
For now, I think the most likely explanation for van Helmont’s results is that E. italicus, T. flavicaudis, or a similar species found its way between his bricks when he wasn’t looking, and not that they were spontaneously generated from basil.
EDIT 10/9/24: The basil → scorpions connection may have been a common belief at the time. Adam Mastroianni recently sent me this passage from Chapter 7, Book 2 of Sir Thomas Browne’s Pseudodoxia Epidemica:
Many things are delivered and believed of other Plants, wherein at least we cannot but suspend. That there is a property in Basil to propagate Scorpions, and that by the smell thereof they are bred in the brains of men, is much advanced by Hollerius, who found this Insect in the brains of a man that delighted much in this smell. Wherein beside we find no way to conjoin the effect unto the cause assigned; herein the Moderns speak but timorously, and some of the Ancients quite contrarily. For, according unto Oribasius, Physitian unto Julian, The Affricans, Men best experienced in poisons, affirm, whosoever hath eaten Basil, although he be stung with a Scorpion, shall feel no pain thereby: which is a very different effect, and rather antidotally destroying, then seminally promoting its production.