The 3rd blog by ‘Ruth Kowslowski’ from The Embalmer’s Book of Recipes, Chapter 15
White spheres lie on cotton-wool in the compartments of a flat wooden box: blue, brown or green circles, dark centres – pot-boilers, money-spinners – artificial human eyes.
On a workbench there are small bottles, pin-boxes and wooden trays containing different body-parts: glass tentacles of different shapes and colours, sponge spicules, tiny shells. ‘Mix ’n match’ invertebrates amongst the powdered glass and pigments. In 1860, Philip Henry Gosse’s Actinologia Britannica was published, illustrated with engravings of coloured sea-anemones and corals. A few years later, an Englishman living in Dresden showed these pictures to glass-maker Leopold Blaschka. ‘Marine creatures preserved in spirits look like grey rubber,’ he said. ‘Why not show their true colours by modelling them in glass?’ Leopold accepted the challenge: he had already made glass orchids, so now he merged his art with science, modelling the exquisite and minute details of invertebrate animals, making them objects for the museum and scientific study rather than ornaments for the drawing-room.
Later, he and his son Rudolf were to give up these animals and Haeckelian embryos for a ten-year commission to make the Harvard glass flowers, but in those early days their business was not yet profitable – so they created jewellery, and glass eyes for cosmetic use by the blind.
We don’t know where Frederik Ruysch obtained the glass eyes to fill the orbits of his embalmed and Death-defying Dutch babies in the 17th century but they obviously did the trick because the babies’ winning looks won the heart of great Czar Peter.
The philosopher Jeremy Bentham, who died in 1832, probably had the foresight to choose his own glass eyes (but he clearly had not planned that his mummified head would be stored in the dark inside his torso).
Can we defy Death, and preserve and repair our ageing body-parts, can the blind really be made to see again? Human eyes are such complicated balls of cells.
William Paley had argued in his Natural Theology in 1802 that the eye, like a telescope, could only have been designed by a Maker. (But the Maker must have been having a visual migraine when he designed the mammalian retina, back-to-front.)
Charles Darwin struggled to understand how these ‘organs of extreme perfection’ could have arisen from chance mutations alone. ‘To suppose that the eye … could have been formed by natural selection seems, I freely confess, absurd in the highest degree,’ he wrote. It’s almost enough to turn one into a Creationist or propose the intelligent mind and hand of a Designer. There is the implication that Evolution had foresight and saw its future goal.
We know now that Evolution is a conservationist and throws very little away: ‘You want an image-forming retina? There’s a bit of photosensitive pigment kicking around somewhere. A bit of this and a little bit of that, let’s try them in this order instead …’ The ingredients are mixed in a different sequence, to a different recipe.
The ingredient pax6 has never been allowed to rest, we need that gene as much as a flatworm does. In the embryo of a fly the product of pax6 directs the development of the eye. Gosse examined an insect’s eye under his microscope in the 1850s: ‘How gorgeously beautiful are these two great hemispheres that almost compose the [dragonfly’s] head, each shining with a soft satiny lustre of azure hue,’ he wrote. ‘You see an infinite number of hexagons, of the most accurate symmetry and regularity of arrangement.’ Each of those ‘hexagons’ contains a lens, and a careful anatomist with a steady hand can prepare an insect’s eye so as to look through it himself.
Van Leeuwenhoek (who lived a mere 50 years from 1675-1725, but achieved so much), looked through his microscope fitted with the prepared eye of a honey bee at a church steeple (‘which was 299 feet high, and 750 feet distant’) and saw multiple inverted images of the steeple. It scarcely seems possible that van Leeuwenhoek could have seen and understood so much of the natural world through a handheld instrument – the microscope is displayed in the Boerhaave Museum in Leiden – that is barely two inches tall.
The surface of the fruitfly Drosophila’s eye resembles a small raspberry. If the pax6 gene is injected into the embryonic cells that should form a Drosophila leg, the raspberry-like eye grows instead. Even more exciting and astonishing is that the raspberry will also grow if the pax6 equivalent from a mouse is injected into the fly embryo! (1) A mouse’s eye is like ours, as different from a fly’s eye as is a fly’s wing from a bat’s. And so it is with pax6 from the squid which, like the octopus, is almost unbelievably related to creeping slugs and snails, and which has an eye that is superficially like a mammal’s (this time, God designed the retina the right way round). Squids, jet-propelled and predatory, need their big eyes to see their prey – the Blaschkas’ glass squid is translucent and delicate, with lustrous dark eyes.
The pax6 gene in the living, growing animals has been conserved, and put to different uses. Biologists have identified it and its related ingredients, they even know something of the recipe from which a human eye is made, but they cannot reproduce it in a culture-dish, they cannot make eyes. Yet.
Biologists can ‘make’ different sorts of cells. Take a fertilised mouse or human egg and nurture it in a culture dish for several days so that its cells divide and divide again, to form a hollow blastocyst. Imagine a football with a pork-pie suspended inside it, and shrink it down in your imagination to the size of a pinhead: that is a 6-day blastocyst and the ‘pork-pie’ is a ball of embryonic stem cells. Stem cells, that each contain the complete book of recipes to form any other type of cell in the growing embryo; ‘the secret of eternal life’, a cellular equivalent of a perpetual motion machine, the magic ingredient that will allow us to repair ourselves for ever. Not quite, but stem cells have their uses.
Van Leeuwenhoek looked through his tiny microscope and watched red blood cells circulating in the blood-vessels of a tadpole’s tail. He would have thought it almost unbelievable that stem cells from a blastocyst could be turned into red blood cells in a culture dish; or into nerve cells, or muscle cells. (He would have been even more disbelieving to see how frogs’ eggs could be manipulated to produce clones).
Scientists can persuade corneal stem cells to grow new pieces of cornea, they can even persuade embryonic stem cells to change into a kind of retinal cell. But they cannot yet grow an eye, and if they could, how would they rewire it to the brain? All those millions of wires bound together in a cable, each needing their own connections in the brain. The Designer made an unintelligent muddle with those wiring diagrams, too, crossing over the cable from the right eye’s socket to the left brain, and vice versa.
William Hunter, FRS (1716-1783), anatomist, and man-midwife to Queen Charlotte and the gentry, dissected many corpses throughout his studies and demonstrations of anatomy. As President of the Royal Academy, he also stressed the links between science and art, and commissioned paintings and drawings of the three-dimensional structures that he dissected, as aids to surgery and deconstruction. Many of the contents of his London collection were transferred to Glasgow after his death. Upstairs in Glasgow’s Hunterian Museum, on a wooden shelf, are multiple rows of jars containing eyes. Intact, they stare at you while you stare at them and, because they are dissociated from their faces you cannot tell whether they stare in hatred or fear or even, perhaps, amusement. Why did Hunter collect so many? Was he working on a study of the anatomy and development of the eye?
But look at this. A woman sleeps sweetly, unaware that her body has vanished leaving only her head with its soft pink lips and perfect teeth, nestling on a silken cloth. We need only see her head because Organ of sight shows the blood and nerve connections to the eye, as known in 1803. Clemente Susini’s wax woman’s eyes are closed, so we need not be afraid.
But the eyes of Ana Maria Pacheco’s wooden sculpted heads engage you at once – stark white with dark irises and pupils, outlined by thin black lines, they look out at us slyly, laughingly, wryly, openly, in sadness and in pain, from their painted wooden faces. In Dark Night of the Soul (1999) the naked victim has his head covered by a cloth so that he may not see the archers aiming at him, or perhaps that we may not look into his eyes and see the terror in this so-called terrorist’s soul. The eyes of the carved watchers reveal their despair and make us weep.
Elsewhere, thirteen heads stare out of a compartmentalised box (Box of Heads, 1983) and their white faces and gashed red mouths catch our glance one by one, and hold it. Individuals, their thoughts are almost visible and we are forced to wonder about them, for though disembodied they seem all too real. (It is not just their eyes, but also their teeth, that make them real, the porcelain teeth, with all the irregularities and imperfections of individual human mouths). The tiny boxed heads are as pale as bleached skulls.
In a tall wooden Cabinet in Museum Vrolik, Amsterdam, rows of skulls are supported by pegs on ebony stands. Hydrocephalus, microcephalus, bathrocephalus, they are all sizes, distorted, grinning toothily but without eyes. Shelves of skulls, a presentiment of the Killing Fields. Nearby is the Curator’s ‘favourite’ specimen, a little foetus with a fuzz of pale red hair, his arms hanging gently in the liquid preserving liquid as though he is merely resting. He is a little ‘cyclops’, whose genetic recipe made for him only one small central eye. He did not live to see the light of day, nor have the good fortune to enter the Country of the Blind.
(1) In the mid-1990s, Walter Gehring and his colleagues performed a series of what turned out to be ground-breaking experiments in the field of developmental genetics – they showed that the gene pax6 which initiates the early stages of eye-formation in the mouse could also initiate eye-formation in Drosophila. Not a mouse eye – but a fly eye. In other words, if the mouse gene was inserted into fly cells that would normally form a leg or antenna – a fly eye grew instead! See Figures 3 and 5 of Induction of Ectopic Eyes by Targeted Expression of the eyeless Gene in Drosophila