The Lagoon Page 7

  SĒPIA – CUTTLEFISH – SEPIA OFFICINALIS AFTER HISTORIA ANIMALIUM, BOOK IV

  XXIV

  ALL ANIMALS INTEREST Aristotle, but none more than humans. They – we – are his ultimate model organism. The term is no anachronism, for Historia animalium begins with an account of human anatomy:

  First the parts of man [anthrōpos] must be grasped. People judge currencies, like everything else, by what is most familiar to them; and human beings are, necessarily, the animals most familiar to us.

  Humans are not, he grants, very typical. He often mentions our peculiarities: that we alone have a face, eyelashes on both lids, variously coloured eyes, are toothless at birth, are erect, have breasts in front and have hands. Nevertheless we are the obvious place to start.

  Did Aristotle ever dissect a man? It is much disputed. Denying it, one sour scholar, Lewes, appealed to Sophocles who depicted Antigone – her sweet, fierce loyalty, her virginal beauty, her vaulting courage – as she fought to bury her brother. This, Lewes says, shows the respect that the Greeks had for their dead, an attitude that would have ensured that Aristotle would never have got his prurient anatomist’s hands on a corpse.

  It is not a strong argument. There were lots of slaves about in fourth-century Greece; one imagines that their unloved, un-Greek cadavers were always at surplus in Athens. Besides, in the next century Erasistratus of Ceos and Herophilus of Chalcedon did, apparently, dissect humans, albeit at liberal-minded Alexandria. The ancient sources even talk of vivisecting prisoners. But we do not need sociological arguments to settle the matter. Aristotle himself is fairly clear that he did not. Turning to our internal anatomy he says: ‘The fact is that the inner parts of man are extremely unfamiliar to us: therefore we must bring along and examine the [inner] parts of other animals whose nature is comparable to man’s.’

  Indeed, extrapolation accounts for some of the inaccuracies that litter his account of our internal organs. He says that humans have a ‘double uterus’ – a good guess since the uteri of most mammals are, to varying degrees, bifurcate, and it’s just too bad that ours aren’t. He says that we have ‘lobed’ kidneys – we don’t, but an ox does. Some inaccuracies are inexplicable. He says that we have eight pairs of ribs – did he never see a skeleton? He records examining spontaneously aborted human foetuses. He does not say that he dissected one, but some of his apparent errors may be accurate descriptions of foetal anatomy.

  No organ system interests Aristotle so much as the heart and its vessels. His discussion opens with the state of play. Syennesis of Cyprus, Polybus of Cos and Diogenes of Apollonia – two Hippocratic doctors and a physiologos – get anything from a paragraph to a few pages. Plato isn’t mentioned at all. Perhaps this is because his model of the cardiovascular system, as given in The Timaeus, is only five lines long.

  The two Hippocratics were hopeless. They started the blood vessels in the head and left the heart out. Diogenes was better and, in what is one of the longest fragments we have from any Pre-Socratic philosopher, Aristotle quotes him at length. Diogenes had the wit to attach the blood vessels to the heart and described the course of some of them in sufficient detail that they can be identified today. All three held that the vascular system is built on a left/right plan: one set of vessels feeds the left testicle, kidney, arm and ear; another, quite separate set feeds their cognates on the right. This, although neat, is wrong.

  Aristotle’s own account, by contrast, is a bravura bit of anatomical research. Where the Hippocratics seem to have traced the vessels visible through the skin or else simply guessed, Aristotle dissected:

  As noted previously, the problem with visual examination is that it is possible to make an investigation effective only if the animals killed by strangulation have previously lost weight.

  And:

  The pointed end of the heart faces forward, but a shift in position during dissection can often cause one to miss this.

  And:

  A detailed and accurate study of the relative positions of the blood vessels should make use of the Anatomies and Enquiries into Animals [Historia animalium].

  HUMAN VASCULAR SYSTEM AFTER HISTORIA ANIMALIUM, BOOK III

  Do not, he appears to warn, think to dispute my results without first mastering my techniques.

  Those techniques gave him a coherent, detailed account of the heart’s structure, the body’s major blood vessels and their relationships and ramifications. Reading it, the thought even occurs that he did, after all, dissect a human; but, looking closer, it’s clear that there’s nothing in it that he couldn’t have got from a goat. He places the heart at the centre of the entire system and orients the geometry of the major blood vessels so that the aorta lies ‘behind’ (dorsal) the ‘great blood vessel’ – the vena cava – as, near the heart, it does. We follow his account of the ‘great blood vessel’ and its tributaries:

  The vena cava runs through the largest of the heart’s three chambers (right atrium + ventricle). The superior vena cava runs towards the upper thorax and then divides to form the innominate veins which then merge into the subclavian veins that run to the arms and the two pairs of jugulars that run to the head. The jugulars give rise to the facial veins and many other small vessels in the head. The inferior vena cava runs through the diaphragm, where it branches into the hepatic vein that invests the liver, and then the renal veins that invest the kidneys, and then continues until it divides into the iliac veins that run down the legs to the toes. The veins of the stomach, pancreas and mesenteries, of which there are many, unite to form a single large vessel. A branch of the ‘great blood vessel’ (the pulmonary artery) divides and then branches and then branches again into ever smaller vessels that invest the lungs.

  The terminology is modern, for Aristotle does not name any vessels except the ‘great vessel’ and the aorta whose tributaries he traces in much the same way. Yet his account is so good that we know what he means even if here his prose, always viscous, clots; it’s so good that we can follow it with modern diagrams in hand; it’s so good that its errors are immediately apparent.*

  But dissection is hard. Open a corpse and you do not see organs neatly arrayed, logically connected and conveniently labelled in contrasting colours, but a morass of dimly discernible tubes and sacs and membranes swimming in pools of bodily fluids. What you see in that morass is deeply influenced by what you expect to see, for in dissection, as in all investigations, expectation and practical difficulties conspire to hide the truth. Expectations and difficulties can, however, sometimes be overcome. Aristotle wonders where the blood goes. He looks and describes, possibly for the first time, how blood vessels branch, and then branch again, until they become tiny vessels, the capillaries, and disappear into the flesh.

  XXV

  WHICH RAISES THE question: just how good is his biology as a whole? Never mind the theory – how many of his simple, descriptive claims are true? This question, one that will occur to any working scientist opening a volume of Aristotle’s biological works and seeing the empirical claims roll by page after page, has never been answered.

  It’s not for want of trying. Over the centuries, many commentators have attempted to assess the truth of Aristotle’s assertions. They have all been defeated by the immensity of the task. Consider the following passage:

  All live-bearing tetrapods have kidneys and a bladder. Some of the egg-laying animals (such as birds and fish) do not: of those that are tetrapods, only the turtle does, with a size proportionate to its other parts. In the turtle the kidney resembles those of cattle. An ox’s kidney looks like a single organ composed of a number of small ones.

  Only three sentences long, it contains six empirical claims: that (i) all mammals have kidneys – true; (ii) all mammals have a urinary bladder – true; (iii) no fish or bird has a kidney – false; (iv) no fish or bird has a urinary bladder – true; (v) among amphibians and reptiles, only turtles have kidneys – false; (vi) the turtle’s kidney, like that of an ox, has a modular structure – true. Aristotle se
ems, then, to have missed the kidneys of fish and birds. Expectation surely played a part in that since the fish and bird kidneys are not kidney-shaped, but are instead long and thin. In fact, in another book, Aristotle says that fish and birds have ‘kidney-like’ parts.

  But grading Aristotle on his knowledge of the excretory system is easy, requiring no more than a passing acquaintance with vertebrate anatomy. What, however, is one to make of his claim (to pick another) that there is a kind of woodpecker, of intermediate size, that nests in olive groves? Filios Akreotis, Greece’s pre-eminent ornithologist, tells me that indeed there is – the middle spotted woodpecker, Dendrocopus medius – but that it does so only in Lesbos.

  And then there are difficulties with the texts. In the euripos Pyrrhaiōn, Aristotle says, you can find the esthiomenon ekhinos, the edible sea urchin. He also says that you can tell this sea urchin (Paracentrotus lividus) from its inedible relations by the seaweed with which it decorates its spines. So one summer day we drove our scooters to the Lagoon’s mouth and snorkelled for the garlanded urchins, cracked their tests or shells open on the rocks, and ate their gonads, the ricci di mare so beloved by Sicilians, raw. Among the debris of our lunch were the urchins’ mouthparts: tiny, intricate devices made of bone-white calcite. In 1734 the Prussian polymath Jacob Theodore Klein described this structure in his Naturalis dispositio echinodermatum; or, rather, he redescribed it, for he noted that Aristotle had also seen it and so, adopting his predecessor’s simile, called the structure ‘Aristotle’s Lantern’.

  It is an iconic bit of anatomy. A zoologist may know nothing about Aristotle but will know of the sea urchin’s mouthparts by Klein’s name. Actually, it turns out that Klein, and pretty much everyone since, misread the texts and that when Aristotle compared the sea urchin to a ‘lantern’ he didn’t mean just its mouth parts at all. An ancient lantern recently dug up from a necropolis in Lethe makes this entirely obvious, for it looks exactly like the sea urchin’s test. The problem lies in the manuscripts: some say sōma (body), others stoma (mouth), and his interpreters have had to choose.

  This is a cautionary tale. To determine the veracity of Aristotle’s observations would take a squadron of zoologists, deeply versed in his thought and able to read ancient Greek, many years. Today such zoologists are rare. A few centuries ago, however, they weren’t. Many could, and did, read Aristotle in the original. They loved what they found. Cuvier set the tone: ‘In Aristotle everything amazes, everything is prodigious, everything is colossal. He lived but sixty-two years, and he was able to make thousands of observations of extreme delicacy, the accuracy of which the most rigorous criticism has never been able to impeach.’ Cuvier, the author of Leçons d’anatomie comparée (5 volumes, 1800–5), Le règne animal (4 volumes, 1817) and Histoire naturelle des poissons (with Valenciennes, 22 volumes, 1828–49) among other monolithic works, was by general estimation, not least his own, the greatest anatomist of his day. He thought that Aristotle could not be faulted – and he should have known.

  He should also have known better. Instead he led the chorus: ‘A master . . . who extends the limits of all sciences and penetrates to their very depths’ – thus Geoffroy Saint-Hilaire fils; ‘His plan was vast and luminous . . . he laid the basis of science which will never perish’ – so de Blainville. That seems excessive. But Owen, Agassiz, Müller, von Siebold and Kölliker, masters of the scalpel in an age when all the animal kingdom came under the knife, all honoured Aristotle. They did so because he founded their science, but also because he knew things that they did not. They loved him, in particular, for having spotted three things that they had to rediscover: the catfish’s paternal habits, the octopus’ penis-arm and the placental dogfish.

  XXVI

  IN THE COOL RIVERS and lakes of Macedon lives a catfish of tender habits:

  A river fish, the male glanis, takes great care of its young. The female abandons them on giving birth, but the male stays and does egg-guarding duty, wherever most spawn has collected. Its only useful service is to prevent other small fish from stealing the offspring during the 40 or 50 days it takes for the offspring to develop, making escape from other fish possible. Fishermen identify where it is on egg-guarding duty by the murmuring sound it makes while giving protection against other tiny fish. It is so affectionate and proprietorial in remaining close to the eggs that it does not abandon the offspring even when eggs attached to deep roots are moved by fishermen into the shallows. Here it can be swiftly caught in the act of grabbing the little fish as they approach. Experienced hook-eaters will not, even so, abandon the offspring but destroy the hooks instead by biting on them with their toughest teeth.

  It is a lovely image. The male catfish, abandoned by his feckless mate, stands his ground muttering belligerently at all comers as his hapless fry huddle beneath his fins. It could be a vignette from a fable. That wouldn’t be completely un-Aristotelian. He describes various animals as being ‘good-tempered’, ‘sluggish’, ‘intelligent’, ‘timid’, ‘treacherous’ and, in the case of one, ‘noble and courageous and high-bred’ – the lion, of course – all of which has an Aesopean ring.

  In 1839 Georges Cuvier and Achille Valenciennes identified Aristotle’s glanis as the wels, Silurus glanis. Too careful to dismiss Aristotle’s account of the fish’s paternal instincts outright, they nevertheless said that it ‘borders on the marvellous’, which it does. In 1856 Louis Agassiz, Professor of Zoology at Harvard University, considered the glanis again. Agassiz was much more inclined to credit Aristotle. Parental care had recently been documented in fish. He himself had seen an American catfish make nests and care for its young, so why shouldn’t a Macedonian one? On the other hand, having grown up in Switzerland, Agassiz knew the habits of S. glanis intimately and had never seen it guard its young.

  The problem was resolved when Agassiz received some Greek fish from one Dr Roeser, physician to the Greek king. In this collection ‘were half a dozen specimens labelled Glanidia, caught in the Acheloos, the chief river in Acarnania, from which Aristotle had himself derived his information about the Glanis. The identity of the name and the place leave no doubt that I am in possession of the true Glanis of the Greek philosopher: that this Glanis is a genuine Siluroid, but not the Silurus Glanis of the systematic writers.’ In 1890, his assistant Samuel Garman described the Macedonian catfish as a new species, Silurus aristotelis, differing from S. glanis chiefly by having four barbels on its chin rather than six.

  Aristotle’s description of S. aristotelis’ breeding habits is exact. At least it is insofar as we know them. In another passage he describes the fish’s courtship, the external fertilization, the ‘sheath’ (egg-envelope) that develops after fertilization, the embryonic eyes that develop a few days later and the unusually slow growth of the larvae. All of this is so detailed that Aristotle may well have studied the fish himself; he lived in Macedon as man and boy. His description of the S. aristotelis’ parental care is also true to life. The females, after having deposited their eggs, do swim off leaving the male to stand guard. And the males do make a ‘muttering’ sound to scare off other fish (by beating their thoraxes with their pelvic fins). There is one puzzling feature of his account. Aristotle claims that the male stands guard for fifty days. This seems a very long time, for the eggs hatch in about a week or so. I have asked experts on this species whether the males also look after the growing fry as Aristotle says they do, but they say they do not know.

  GLANIS – ARISTOTLE’S CATFISH – SILURIS ARISTOTELIS

  Someone should investigate, for Aristotle may yet have things to tell us about this fish. They should do so soon: the IUCN (International Union for Conservation of Nature) lists S. aristotelis as ‘endangered’.

  XXVII

  THE PAPER NAUTILUS, Argonauta argo, is a creature rather like an octopus. The animal itself is unimpressive, but its shell is beautiful. As thin and white as eggshell, it has a perfect planispiral geometry. And, although the paper nautilus is pelagic, living far out to sea, it is often was
hed ashore. After storms they can be found by the hundreds, dying on the beach.

  In 1828 Delle Chiaje, an otherwise obscure Italian anatomist, studying paper nautili in the Bay of Naples, found that they appeared to be infested with a parasitic worm. He called his worm Trichocephalus acetabularis or ‘hairy-headed sucker’. A year later Cuvier discovered a similar worm on an octopus at Nice. He called his worm Hectocotylus octopodis or ‘cups that hold on [to] an octopus’.

  There was nothing very remarkable about the discovery of a new parasitic worm. Marine animals are infested with them. Hectocotylus was, however, a strange sort of parasite for it oddly resembled its host. Its suckers looked very cephalopod-like. Suspicion grew that it was not a worm at all. In 1851 Heinrich Müller and Jean Baptiste Vérany independently showed that Hectocotylus, far from being a parasite, was in fact the paper nautilus’ spouse, more precisely, its spouse’s penis. All the paper nautili in the world that have ever been seen are, it seems, female; the male is an obscure and dwarfish creature that does not make a shell at all. One of his tentacles is a highly modified intromittent organ that, during copulation, snaps off in the female’s mantle cavity, leaving the male with no penis, or one less tentacle, but in any event one less appendage than he started out with.