Organism of the week #26 – Oxymoron
Plants can have some very odd names. Bears are not renowned for their trousers, and this spiky sod is the last thing anyone would want to make a pair of trousers from, but "bear's breeches" it is. Even its Latin name is odd: acanthus means spiny, and mollis means smooth; a literal oxymoron.
It might not look very familiar, but it may be the most quietly famous plant in the world, having been immortalised in stone through much of the world for over 2000 years.
As any classicist – and many a bored sixth-former stuffing their CV with General Studies – can tell you, there are three ways to cap off an architectural column in the Greek style: plainly, fussily, or gaudily (the Romans later added boringly and ludicrously).
The gaudy version is decorated with the leaves of Acanthus: you can see them here at the top of the columns outside the Royal Institution in London:
Royal Institution (T.H. Shepherd)
Why Acanthus was chosen rather than any other local Mediterranean plant is as much a mystery as the plant's strange common name. There is a story, quoted by Vitruvius, that Acanthus was found growing through a votive basket left on the grave of a young girl, and this inspired the sculptor and architect Callimachus to invent a new kind of column. This sounds about as likely to me as those ridiculous backronym etymologies of swear words ("Fornicating Under Consent of the King" – yeah, right), but whatever the reason, I think it's rather nice that Callimachus (or whoever) elevated a obscure, prickly thing like Acanthus to such heights, rather than going for an obvious, safe choice like grapes or olives. But I guess I would, wouldn't I?
Acanthus, architecture, corinthian
Organism of the week #25 – Bull headed
This is another of the things we have found down a microscope in one of our undergraduate practicals, but for once it's not a ciliate.
Bucephalus minimus
This is the larva of a parasitic fluke called Bucephalus, which is the Greek for 'bull headed'. It's appropriate for this fluke not because it looks like Alexander the Great's horse, but because its two "tails" (furcae) look like horns when they are fully extended.
Bucephalus as interpreted by Ernst Haeckel
Like most of its relatives, Bucephalus has a ludicrously complicated life-cycle, making life miserable for no less than three separate hosts: a mollusc (typically a clam), a small foraging fish (like a smelt or goby), and a larger predatory fish (such as a sea-bass):
Bucephalus life-cycle [CC-BY-SA-3.0 Steve Cook, Didier Descouends, Citron, Roberto Pillon]
Two of these hosts – the clams and sea-bass – are economically important sea foods. Like many flukes, the larval stages in the first intermediate host – the clam – chemically castrate the host so that it diverts more resources to the survival and propagation of the parasitic fluke than it does to its own. In the sea bass – the definitive host, where the fluke reproduces sexually – the adults are found in the fish's gut, and heavy infections cause weight loss in both wild and farmed fish.
Although Bucephalus cannot infect humans, we are the definitive host for several other flukes, most importantly the liver fluke, the Chinese liver fluke, the intestinal fluke, and the blood fluke that causes schistosomiasis (bilharzia). These have similarly complicated life cycles involving molluscs and assorted other intermediate hosts, and between them they infect many tens of millions of people worldwide.
Drug treatment options for fluke diseases tend to be limited and have unpleasant side effects, and schistosomiasis in particular is on the WHO list of neglected tropical diseases, for the damning ratio of infections in the developing world to investment made by the developed world in its treatment and prevention. It really is about time this changed.
Bucephalus, fluke, microscopy
A graph to show
I've never been sure where "a graph to show…" comes from. As far as I can tell, A-level specifications don't use or specify this wording, and you wouldn't typically see it in a figure legend in a scientific paper. But if you ask first-year students to put a title on a graph without any further guidance, almost every one of them will default to this mindless boilerplate.
I hate "a graph to show how y varies with x" with a passion bordering on pathology.
"A graph to show" tells me nothing whatsoever that a properly drawn graph doesn't already show. It is as superfluous as gold paint on a lily or jackboots on Theresa May:
If it's an x,y scatter-plot, then the y axis will have a clear label, stating what y is in terms that the expected audience will understand, including details of the units in which y has been measured (if any).
If it's an x,y scatter-plot, then the x axis will also have a clear label with the equivalent details.
If it's an x,y scatter-plot, then you presumably wouldn't have plotted such a thing if you didn't want to show me how y varies with x.
And finally, if it's an x,y scatter-plot, then the very last thing you should waste your breath or word-count telling me is the fact that it's a "graph". I know it's a graph, because – you know – it's got f**ing axes and f***ing data points and all the other sexy trappings of graphdom.
Titling a graph with "a graph to show how y varies with x" is a waste of time. But it's worse that that. By training students to write mindless titles, you divert their attention from actually writing a title (and/or legend) that are useful to the reader, and to the writer.
A useful title should tell the reader enough about how (and why) the data has been collected for the graph to stand alone.
Some real(ly annoying) examples:
A graph to show how the absorbance varies with wavelength
The absorbance of what chemical? Wavelength of light, or of some other wave? How does it vary? Why should I care? Does a graph that shows absorbance (or emission) against wavelength of light have a specific name?
A graph to show how the rate of the enzyme varies with pH
Which enzyme? What substrate? How does it vary? Is there – perhaps – an optimum? What pH value gives this optimum? Is it (in)consistent with the typical pH values in which this enzyme is found?
A graph to show how the pH varies with the amount of base added to the acid
Which acid? Which base? What concentrations? Does it buffer? How many times and at what pKa values? Is there a specific name for this experimental procedure?
A graph to show how the number of lichens in a wood varies with size
Number of lichens or number of species of lichen? Which wood? Latitude and longitude? Presumably the size of the wood, not the lichen (do you mean 'area'?) Is there a well-known mathematical relationship between these two variables? What parameters have you estimated from it?
Writing better graph titles means really thinking about what your data show and how they were collected. Putting in the effort to give your graphs meaningful titles will result in better discussion of those results. And if you don't…
A graph to show how your score will vary with the number of times you say "a graph to show how y varies with x"
Organism of the week #24 – Danse Macabre
For three centuries, the Black Death was routinely epidemic in London. The first outbreak – in 1348 – probably killed half the population of England; the last outbreak – from 1665 to 1666 – probably killed a quarter of the population of London.
In 1665, Isleworth was a small village several hours' walk (or row) from London proper, but the Great Plague found its way there anyway. As in many places, so many died that digging individual graves became impractical, so instead, the bodies were interred in communal plague pits.
All Saints' Isleworth plague pit memorial
Isleworth is one of the few places in present-day London where there is evidence above of the burials below. A cairn of stones and a yew tree sit atop the pit and mark the resting place of the 149 people who died there.
"THIS YEW TREE COVERS THE SITE OF THE PLAGUE PIT IN WHICH 149 PERSONS WHO DIED DURING THE GREAT PLAGUE OF 1665 WERE BURIED"
Yew trees (Taxus baccata) have long had an association with churchyards. The optimistic may consider this appropriate because yews are an evergreen reminder of the life eternal; the cynical may have other analogies to draw.
Taxus baccata yew trunk at All Saints' Isleworth
Since the 1980s, there has been some debate about the cause of the Black Death. The majority of evidence pointed to the bacterium Yersinia pestis, a parasite of rats and other rodents that gets from place to place in the guts of fleas, and causes swelling of lymph nodes, fever, coughing, bleeding under the skin, gangrene and – all too frequently – death.
Flea from Robert Hooke's Micrographia. I still can't believe the lovely people at the Royal Institution let me touch it
In particular, an outbreak of Y. pestis plague that started in China in 1885, and continued worldwide until 1959, had similar symptoms to those reported by mediaeval scholars for the Black Death. However, some remained unconvinced, and pointed the finger instead at haemorrhagic fevers, anthrax, or other agents.
Yersinia pestis bacteria in the gut of a flea [Public Domain, credit: NIH]
Recent evidence from DNA sequencing of samples taken from plague pits and other burials appear to back up Y. pestis as being the culprit for both the mediaeval Black Death and the even earlier Justinian Plague, which devastated the Byzantine Empire in 541-542.
Plague is currently easily treated with antibiotics like streptomycin if caught early enough, but it's never really gone away: rodents still carry plague in the US, India, China, Brazil, and southern Africa, and all of these countries have reported infections in the last 40 years.
It's strange to think that one of the greatest killers in all of human history, exists not just in GCSE history books, but also out there in the real world.
Waiting patiently in the shadows.
black death, flea, plague, Taxus, Yersinia, yew
Organism of the week #23 – Rattled
My annual summer ritual to stave off death for one more year involves running round Kensington Gardens and Hyde Park, which are situated conveniently close to $WORK.
I lumbered merry as a shroud.
That aches and sweats o'er trails and heights,
When all at once I saw a crowd,
A host, of golden parasites:
Yellow rattle growing in the north of Kensington Gardens (Rhinanthus minor)
Yellow rattle is a member of the broomrape family, which are almost all parasites of other plants. Broomrape itself is completely parasitic, and obtains all the sugars and other nutrients it needs to grow from other plants.
Broomrape (Orobanche minor) is a plant that completely lacks chlorphyll so is a ghostly white colour [CC-BY-SA-3.0 Rosser1954]
This is why it has no need for the green pigment chlorophyll, which most plants use to capture sunlight. Yellow rattle, as you can see from the image below, has normal-looking green leaves, so it must be making at least some of its own food.
Yellow rattle flowers and leaves
So how do we know it's a parasite? If you very carefully dig up yellow rattle roots, you'll find they grow tightly around the roots of grasses and other nearby plants, and make physical connections with them. The rattle uses these connections to tap into the roots of other plants and to steal their water and nutrients. It'd be nice to show you this, but whenever I'm near these plants I am a sweaty, exhausted mess and it's all I can do to take a photo, let alone go digging. Also, as it's a Royal Park, digging up rattle is probably treason or some similar nonsense.
You'll have to make do with circumstantial evidence instead. The big bald patch in the image below is where the rattle is growing. The grass is about half the height of the grass surrounding the infested patch, and much sparser.
Bald patch in a sward of grass caused by yellow rattle infestation
[If you're a good ecologist, you might suggest that is is merely evidence for competition rather than parasitism, and you'd be right.]
At the end of flowering, the plant dies, leaving just a spike of seed capsules:
Yellow rattle capsules (bottom of image) mixed in with unhappy grass
It's the capsules that give the rattle its name: they make a satisfying noise when gently jiggled.
Although the rattle does damage the grass, it has a positive effect overall on the biodiversity of the field by keeping the grasses in check. As yellow rattle allows other species to grow that would normally get shaded out, it makes for a useful addition to those wildflower meadows that are nearly as beloved of the chattering classes as is the middle-aged PE of running round parks.
Apologies to William Wordsworth, and poetry more generally.
yellow rattle; Rhinanthus; parasite
Phage vs. host
By polypompholyx in Evolution, Teaching
For a recent schools' outreach day, I put together a card-game based around the arms-races that develop between bacterial hosts and their viruses (bacteriophages). It's mostly just a bit of fun, but if anyone finds it useful or can suggest improvements (or just make them! I release this under a CC-BY-SA-4.0 license) I'd be happy to hear them.
game, phage
We had the annual "looking at muck down a microscope" practical last week. As usual, the best thing we saw was a ciliate in some pond water, in this case a little trumpet animalcule:
Stentor sp. The green bits are either symbiotic algae, or dinner, possibly a bit of both.
Previous winners: Vorticella and Lacrymaria. The Ciliata really are the phylum that keeps on giving.
ciliate, microscopy, Stentor
A queen's Christmas message
Well, at least 2:8 is plausible.
2:1 And it came to pass 10 years after the death of Herod the Great, that there went out a decree from Caesar Augustus that all the world – except those irrelevant bits that the Romans hadn't conquered – should be taxed.
2:2 (And this taxing was first made when Quirinius was governor of Syria during what – by a large stretch of the imagination – may have been his second term, his first (entirely undocumented) term having been in 4 BCE, during which an (entirely undocumented) census almost certainly didn't take place either.)
2:3 And all went to be taxed, every one into his own ancestors' city, in direct contravention of previous Roman policy and of common sense.
2:4 And Joseph also went up from Galilee, out of the city of Nazareth – perhaps using his wooden time-machine to travel back through the centuries required for the town to come into existence – into Judaea, unto the city of David, which is called Bethlehem.
2:5 To be taxed with Mary his espoused wife, being great with her child, whom she claimed – completely plausibly – to have fallen into her womb from heaven, rather than to have been formed in the usual grisly fashion.
2:6 And so it was, that, while they were there, the days were accomplished that she should be delivered of her son, in accordance with a variety of mistranslated prophesies that meant something quite different.
2:7 And she brought forth her firstborn son, and wrapped him in swaddling clothes, and laid him in a manger; because there was no room for them in the inn, this being full of the whole population of Judea, who – like Joseph – had unrealistic ideas about Fisher's relatedness coefficient and the importance of Y chromosomes.
2:8 And there were in the same country shepherds abiding in the field, keeping watch over their flock by night.
2:9 And, lo, the angel of the Lord came upon them. The glory and bowel-loosening terror of the Lord shone round about them: and they were sore afraid, particularly of the cherubim.
2:10 And the angel said unto them, Fear not: for, behold, I bring you good tidings of great joy, which shall be to all people. For some value of 'people'. And of 'all'.
2:11 For unto you is born this day in the city of David a man who is God, and also the son of God, and also the son of a girl from a town that doesn't exist. But definitely not the son of Joseph. Despite the effort we've gone to in establishing his back-story.
2:12 And this shall be a sign unto you; Ye shall find the logical abomination wrapped in swaddling clothes, lying in a manger, possibly attended by a number of Persian priests or kings or wise-men, whom the author of this document will casually forget to mention.
2:13 And suddenly there was with the angel a multitude of the four-faced, six-winged heavenly host praising God, and saying,
2:14 Glory to God in the highest, and on earth peace and good will toward men, except Monophysites, Monothelites, Arians, Nestorians, Manichaeans, Marcionites, Ebionites, Sadducees, Pharisees, Docetists, Cathars, and especially not towards those bloody atheists.
2:15 And it came to pass, as the angels were gone away from them into heaven, the shepherds said one to another, Let us now go even unto Bethlehem, and see this thing which is come to pass, which the Lord hath made known unto us.
2:16 And they came with haste, and found Mary, and Joseph, and the babe lying in a manger.
2:17 And when they had seen it, they made known abroad the saying which was told them concerning this child, surely much to Joseph's delight.
2:18 And all they that heard it wondered at those things which were told them by the shepherds. You would wonder about it, wouldn't you? Wouldn't you?
2:19 But Mary kept all these things, and pondered them in her heart, for she knew that her remaining verses were numbered.
2:20 And the shepherds returned, glorifying and praising God for all the things that they had heard and seen, as it was told unto them.
2:21 And (as will probably be prudishly edited out when you hear this read in the dim and distant future), when eight days were accomplished for the cutting off of part of the child's penis, his name was called Joshua, which was so named of the angel before he was conceived in the womb.
A very Merry Joshuamas to you all.
Joshuamas
Organism of the week #22 – Faking it and making it
Nettles have a rather unhappy reputation as bringer of painful welts, and – at this time of year – dribbling noses too. The welts are probably caused by histamine, and the pain by oxalic and tartaric acids, which the nettle injects into your skin through the tiny brittle hairs that cover its stems and leaves. If you're stung badly, the pain can last for several hours.
Stinging nettles (Urtica dioica) in Russia Dock Woodlands, Rotherhithe
If you are stung by nettles at some point, you'll probably avoid trampling barefoot on them in future. If getting trampled by humans is a big ecological problem for nettles, then a less stingy nettle stands a poor chance of growing up to make baby nettles. Stingless nettles will therefore go extinct, and their stingier competitors will inherit the earth. Praise be to Darwin.
Stinging nettle stinging hairs [CC-BY-SA-3.0 Frank Vincentz]
Unfortunately for you (and fortunately for those who make a living from it), it's almost always true that "I think you'll find it's a bit more complicated than that" in biology. If humans can be persuaded to avoid meddling with nettles through a single painful experience, there is a lot of opportunity for cheats to exploit your fear. In the case of nettles, one well-known group of cheats are the so-called dead nettles:
Yellow archangel, a common dead nettle (Lamium galeobdolon)
The leaves of dead nettles look remarkably like those of stinging nettles, but the dead nettles neither sting, nor are they even close relatives of stinging nettles: stinging nettles are related to hops and cannabis; dead nettles to mint and sage. The flowers give the game away at this time of year, but in spring, the two plants are really very similar. You need to get quite close to spot the missing stings on the dead nettles, and if you've had a bad experience with the real thing in the past, getting quite close is probably something you – or a fluffy wuffy bunny, or whatever – would think twice about.
Stinging nettle (Urtica dioica) and white dead-nettle (Lamium album): spot the difference. The dead nettle has conspicuous white flowers; the stinging nettle's flowers are greenish-brown tassels
Good biologists should always be skeptical of plausible stories, so I should add that I've not actually been able to track down any experimental studies seeing whether bunnies who have learnt to avoid stinging nettles also avoid dead nettles, let alone any that show dead nettles are more successful at making seeds when real nettles are in the same area. Assuming this actually is the case, dead nettles would be "Batesian mimics" of stinging nettles, or – if you'd rather – fakers. They don't have to waste energy making histamine and oxalic acid and hypodermic needles; they merely have to look somewhat similar to stinging nettles to receive all the benefits of having bunnies avoid them, with fewer of the costs.
But what would happen if dead nettles were such good fakers that they became very common? The bunnies would rarely meet the real thing, and would probably never learn to avoid nettle-like plants of any sort. Even if the bunnies did occasionally meet stinging nettles, those reckless bunnies that threw caution to the wind and ate things that looked like nettles would still tend to get more to eat than more cautious bunnies. In either case, the dead nettles would get nibbled back into relative rarity. And then the more reckless bunnies would get stung more often, as they'd meet real stinging nettles more frequently, and this would – in its turn – favour bunnies that were more cautious again, leading to a resurgence of the dead nettles. And so on, and so on.
The relative rarity of dead nettles and stinging nettles wouldn't necessarily roller-coaster up and down like this: the cycles could be quite small. However, it's interesting that neither a field of dead nettles on their own, nor of stinging nettles on their own, is stable. A field of nothing but stinging nettles is prone to invasion by fake dead nettles; but if the number of dead nettles gets too high, the bunnies will never meet the real thing, and won't learn to avoid nettle-like plants in the first place. There is likely to be some ratio of real to fake nettles (and of cautious to reckless rabbits) that is stable in the long term, but it won't be 0% or 100%.
These sorts of 'game' between mimics – the dead nettle "fakers" – and their models – the stinging nettle pain "makers" – are very common in biology, and are an important part of the ecology of many organisms. Wherever an organism has made some sort of 'effort', there is likely to be a living made scrounging off them, or mimicking their appearance.
But of course, it's always a bit more complicated in biology. Not all mimics are fakes. Some mimics benefit from looking dangerous because they really are dangerous.
Honeybee (Apis mellifera), bumblebee (Bombus terrestris), cinnabar moth caterpillar (Tyria jacobaeae), hoverfly (Eupeodes luniger)
The honeybee and bumblebee in the image above both have black and yellow striped bodies. Both are able to sting, and both seem to have similar colours. Is one mimicking the other, and if so, why?
As I said earlier, you should be skeptical of plausible stories. Bumblebees and honeybees are quite closely related, so perhaps the black-and-yellow is just a colour-scheme they've inherited from their common ancestor that has nothing to do with mimicry. We need more evidence.
As it turns out, there is very good evidence that black-and-yellow is meaningful mimicry, not accidental similarity. For example, the cinnabar moth caterpillar in the third image is not closely related to the bees, so it is likely that this caterpillar's colours have evolved independently from those of the bees. Can it sting? Not exactly, but it is poisonous, because it mostly eats ragwort, and it steals the ragwort's poisons for its own defence. Any bird that has learnt to avoid black-and-yellow insects through unhappy run-ins with bees is likely to avoid this caterpillar too. Importantly, this works both ways: any bird that's had a bad experience with cinnabar moth caterpillars is also likely to avoid bees (and wasps, and other similar insects).
This sort of mimicry, where makers – the animals and plants that can back up their threats – all come to have similar warning colours is called Müllerian mimicry. If you need any more convincing, it's telling that there are also many Batesian fakers of the black-and-yellow "warning" colour-scheme too, like the harmless hoverfly shown in the fourth image.
The natural world if full of liars and cheats; except when it isn't.
Lamium, mimicry, nettle, Urtica
As of today, I will have spent precisely half of my life at $PLACE_OF_WORK.
I first arrived at what would become my workplace as a badly coiffured youth in 1995 to do a biology degree. South Kensington seemed a great improvement over Croydon, where I had endured my previous 18 years: there was a refreshing absence of casual street violence, and a greatly improved proximity to the grubby delights of Soho. At that time, my Hall of Residence was directly above the first-year lecture theatre, and in the same building as the Students' Union. Despite this tempting proximity to cheap vodka – and even cheaper dates – I somehow managed to attend almost every lecture of my first year, aside from a week (a week!) of lectures on algae, which I traded for bossing Munchkins about in the Questor's Theatre in Ealing. I met my personal tutor at least twice, survived two under-catered field-trips to somewhere, somewhere in a field in HampshireBerkshire, and made friends whom I treasure to this day.
I discovered a cache of mediaeval exam papers in the bottom of a filing cabinet when I last cleared out my office. I have a very distinct memory of answering this question, probably because it involved talking about the "Sexy Sons" hypothesis.
Second-year forced me out into less convenient accommodation: an ill-conceived double-Georgian knock-through near Brompton Cemetery with 18 bedrooms, and anything up to 2 working bathrooms on any given day. Due to sometwo else both failing their first-year exams, I found myself promoted to Homosexual in Chief of the LGBT society, for which dubious honour I now have a pot behind the Union bar.
I am number 2 on the list of Chief Homosexuals. I believe number 1 is now advising the Lib Dems on election strategy. I suspect this pot may be cursed.
My final-year project on copper-tolerant fungi somewhere, somewhere in that field in Berkshire led to the offer of a PhD in wood preservation, which I leapt upon, having received no careers guidance whatsoever up to that point, and having begun to fear moving back to Croydon for want of any botanical PhD opportunities in London. My undergraduateship ended with a viva voce, upon which I thought hung the fate of my entire degree; in fact, I turned out to be a control, and what I had thought would be a bowel-loosening grilling turned out to be entirely unmemorable.
I had to hire my suit for the Summer Ball just before I graduated. I still hate wearing suits of any kind, which probably contributes to my unemployability outside of academia.
Like most postgraduate research degrees, mine was a heady mix of disappointment, poverty, and the growing realisation that week-day nights-out were incompatible with competent laboratory work. My department had moved out of the timeshare flat with the Students' Union and into a brand-new building during the summer between my BSc and PhD, but someone had been a little unrealistic about the space available in the new labs. The first and second years of my PhD were spent trying not to poison myself with arsenic trioxide amongst a labyrinth of broken vacuum impregnators, quickfit glassware, and bottles of solvent with labels written in Linear A; the third and fourth years spent trying to fit research into the gaps between the demonstrating in lab practicals I had to do in order to have enough money to eat. Somehow I captured the heart of a young aeronautical engineer, who has miraculously put up with my questionable charms ever since.
I presented my ground-breaking findings on the bacterial biotransformation of an anti-sapstain chemical to a conference in glamorous Cardiff, and left it at that. My contribution to the greater knowledge of humankind will forever be a few grey literature conference proceedings, and a large blue book buried in quicklime below the College library.
I occasionally have nightmares about being buried under a landslide of poorly preserved pallet boards.
Having drifted into a PhD, I continued on my under-thought career path by applying for a three-year post-doctoral position that combined part-time research with a part-time PGCE in secondary school education. In retrospect, combining the laugh-a-minute relaxation of academic research with the delights of herding teenagers through GCSEs may not have been the best life decision I've made. There were amusing moments – the attempts of year 7 students to embarrass me during sex-ed lessons were doomed from the start – but mostly it was exhausting and impossible. I somehow made it through to the other side, but with no interest whatsoever in ever darkening the door of a secondary school or research lab again.
Simulating woodlice: anything was better than differentiating my citizenship lessons for kinaesthetic learners [sic]
Fortunately, I had kept up a bit of lab demonstrating on the side, and had even been roped into giving a few first-year lectures in the twilight of my PhD. A temporary position opened up convening a first-year biology course, giving a few lectures, and running some of the practicals I'd been demonstrating for the best part of a decade. And so began a slow accretion from 'stop-gap teaching gimp' to 'senior teaching fellow'.
One of my major roles is the conversion of caffeine into grades.
Many of the staff who taught me as an undergrad have since retired or moved on; even the new-born building of 1998 is now old enough to legally have sex and drive a moped. Some 1700 students have learned – or at least endured – first-year molecular biology and enzymology with me, and the pile of marking in front of me (for which writing this banal drivel is the sort of displacement activity against which I've hypocritically warned those very students) probably contains the ten thousandth script I have scrawled with the Biros of judgement.
I probably ought to get back to it.
In confirmation of the universe's pitiless malevolence, I now give the lectures on algae that I skived off in my first-year.
Aleph-naught bottles of beer on the wall, aleph-naught bottles of beer, you take one down, you hand it on round, aleph-naught bottles of beer on the wall