Wednesday, 20 April 2016

The awesome cyanotypes of Anna Atkins

The digital age has made it easy for us to identify plants and animals using selections from the millions of illustrations that are available on the Web. Accessing images of specimens was a much greater challenge in the Nineteenth Century, just when more and more people were becoming interested in Natural History and wanting to identify plants and animals they collected from the countryside, or the shore.

One solution to the need for illustration was the use of line drawings, or watercolours, that could be made into plates, printed and thus appear in books. A good example comes in the work of Philip Henry Gosse, who was both a scientist and an able artist, so knew exactly which features to portray. Other approaches used real specimens preserved in spirit, or by taxidermy, but these were only readily available in Museums and similar collections. Freshly-collected plants could be compared with those in herbaria, labelled collections of pressed and dried specimens, but these also were not widely available, although many amateurs made their own. However, they were dependent on the herbaria, and illustrations, of experts to ensure accurate identification. Mary Wyatt used herbarium specimens of seaweeds to allow the publication of a necessarily limited number of books to aid identification, while Bradbury and others extended this approach by pressing plants on to lead plates to make an impression. Each of the plates was then coated with copper and could be used to print many copies, some in monochrome and some using colour for even greater realism [1]. Like illustrations made from engravings of other art work, these become available widely [2,3].

Of the many examples of Nature Printing, among the best known are the cyanotypes of Anna Atkins, the daughter of John George Children FRS, for whom she had earlier prepared 250 woodcuts of shells for his translation of a work by Lamarck, the original not being illustrated [4]. Through her father, she had contacts with Herschel and thus the early development of cyanotypes in which chemicals are transformed by light to give a blue background, with the subject blocking the effect of light and appearing white. With her keen interest in illustration, Anna Atkins made cyanotypes of seaweeds that were then bound into a small number of volumes.

Complete collections of Anna Atkins cyanotypes have become justly famous – and very valuable. I was privileged to look through the large collection that was owned by Frederick John Horniman and is now held by the Horniman Museum in London. Each is printed on watermarked Whatman paper, mostly of 1846 and 1849 in the volumes that I saw, and all have a wonderful quality. As aids to identification, they give dimension and the arrangement of fronds of the seaweeds but no natural colour. One would be hard pressed to identify fresh specimens from some illustrations, especially of small algae, or those that are toughened with natural strengthening (see the images below for examples). Mounting specimens that were translucent meant that some surface, and internal, detail became visible and these cyanotypes are especially impressive.

Anna Atkins labelled each sheet with the Latin binomial of the seaweed and this would have been written in ink on strips of paper that were then cleared, most probably using highly refined oil. The labels could then be mounted with each alga and their outline is seen clearly in the prints at the Horniman Museum. Whatever their practical use, the Anna Atkins cyanotypes are beautiful works of art from Nature and it was a privilege to see them. Soon to be superseded by photography, they mark an exciting step in the Art – and Science - of Biological Illustration [3].


[1] Roderick Cave (2010) Impressions of Nature: A History of Nature Printing. London, The British Library.

[4] A. E. Gunther (1978) John George Children, F.R.S. (1777-1852) of the British Museum. Mineralogist and reluctant Keeper of Zoology. Bulletin of the British Museum (Natural History) 6: 75-108

I am grateful to Helen Williamson and the Horniman Museum for letting me see these valuable works and for allowing me to reproduce pictures of them in this blog post.

For those wanting to make cyanotypes of their own, a video explaining the technique can be found at: and I recommend Roderick Cave's brilliant book (reference [1] above) as an introduction to all aspects of Nature Printing.

Friday, 15 April 2016

Jo Atherton's Anthropocene Prints

Jo Atherton makes beautiful prints (below) from plastic flotsam and jetsam gathered from the shore. The first time that I saw them I was reminded of natural aggregates within water bodies, perhaps because these were a research interest of mine [1].

Marine aggregates vary in size, from the minute (a few micrometres across – the scale bar in the micrographs below shows 2 micrometres [with acknowledgement to Ransom et al., 2]) to masses that are visible to the naked eye and which can coalesce to cover water bodies. The aggregates are bound by organic matter produced by algae and bacteria [1] and many sink through the water column and end up on the bed of oceans, especially after storms. Waves generate many billions of bubbles and these enhance the aggregation process, although it also occurs within the water column from collisions brought about by currents, turbulence, and biological processes. 

Jo's Anthropocene Prints complement her Flotsam Weaving [3] that uses plastic rope, Lego figures and many other anthropogenic materials that float around the oceans and drift on currents before coming ashore or being washed up by waves from the shallow continental shelf. Anyone making a sea crossing will be familiar with flotsam; large-scale ocean currents gather this material and transport it very large distances. Recently, we have been made aware of this by the findings in the western Indian Ocean of fragments of Flight MH370 that crashed into the sea near Australia and impressive amounts of material from the Japanese tsunami of 2011 have also been washed ashore along the west coast of North America. This is movement of plastics and other anthropogenic materials on a large scale and much will have sunk to the sea bed, a process aided, for tiny fragments, by the aggregation process I mentioned earlier.

The transfer of matter to the ocean floor from the water column is a continuous process that has occurred over very long periods of time; sediments being laminated and eventually transforming into rock. We are familiar with massive chalk deposits like the White Cliffs of Dover, but less familiar with how they were formed. Much of the chalk comes from calcium salts present in quantity in ancient oceans, much as they are today. However, the chemical was deposited having been extracted by organisms that use(d) it to form protective coatings, the most important being the single-celled coccolithophores (above). It is hard to imagine the number of "shells" falling to the ocean floor, and for how long deposition took place, to accumulate the large deposits of chalk found around the world. All this calcium would have been transferred from the water column in the form of aggregates containing the "shells" of these minute creatures. As many gardeners know, chalk deposits contain flints and we think that these have a quite different origin, being rich in silicon and probably originating from the casing of diatoms (single-celled algae that build these extraordinary glass-like frustules, below), or from siliceous spines, or webs, produced by some animals. After death of the algae, their coats become enmeshed in aggregates and slowly sink to the ocean floor where they become concentrated in some areas and mix with the other silicon-based biogenic materials. The process by which these concentrated masses are transformed into flints is poorly understood.

Limestone is even more abundant than chalk and consists of calcium salts, but with origins in marine shells, corals and the calcareous structures created by a whole range of creatures. Most of these were bottom-dwelling, although some lived in the water column and sank after the death of the animals that produced them. Imagine a shell beach being compacted over time and you get some idea of how limestone was formed, and the model becomes even more realistic if one includes all the other fragments that become washed up. This process occurs underwater as well as at the ocean margins.

Future chalk and limestone deposits will be rather different to those of the past. Those being laid down during the Anthropocene, will not only contain natural materials, but much that is anthropogenic. On the substratum, organic matter is broken down and re-utilised through the microbial community and onwards up a food chain, but plastics are much more resistant to breakdown. If humans, or their evolutionary successors, survive to investigate the geology of Anthropocene rock deposits they will be surprised at their content and at the origins of some of the components. It is also possible that the effects of heat and pressure over very long time periods will transform some of the plastics into oil - returning them from whence they came...

Please take a look at Jo's work [3] and I am sure that it will inspire you as it has me.

[1] Roger S. Wotton (2005) The essential role of exopolymers (EPS) in aquatic systems. Oceanography and Marine Biology: An Annual Review 42: 57-94.

[2] Barbara Ransom, Kevin F. Shea, Patti Jo Burkett, Richard H. Bennett and Roy Baerwald (1998) Comparison of pelagic and nepheloid layer marine snow: implications for carbon cycling. Marine Geology 150: 39-50.

Tuesday, 12 April 2016

Recent unicorns

In popular culture, a unicorn is a white horse with a bony tusk, like that of a narwhal, on the front of its head. However, not all of them have this form. The two supporters of the Royal Coat of Arms of the United Kingdom (see below) are a lion and a unicorn, but this example, while being mainly horse-like, has a very long tail bearing tufts of fur and it also has cloven hooves. This is confusing to a Biologist interested in these animals, as unicorns thus have the characteristics of both perissodactyls (odd-toed ungulates, e.g. horses and rhinoceroses) and artiodactyls (even-toed ungulates, e.g. sheep, goats, deer, cattle). Although they are mythological creatures, there has always been a fascination with the possibility of finding one.

In The Romance of Natural History, Philip Henry Gosse [1] includes reports of sightings of unicorns from Africa and he describes a drawing made of a cave painting:

In this were represented, with exceedingly characteristic fidelity, several of the common antelopes of the country, such as a group of elands, the hartebeest, and the springbok; while among them appeared, with head and shoulders towering above the rest, an animal having the general character of a rhinoceros, but, in form, lighter than a wild bull, having an arched neck, and a long nasal horn projecting in the form of a sabre.

This unicorn was a giant rhinoceros, of a type now extinct, which co-existed with humans perhaps tens of thousands of years ago. Recently, remains of Elasmotherium sibiricum, named the "Siberian Unicorn", were found in shallow sediments in Kazakhstan. Shpansky, Aliyassova and Ilvina [2] were able to date the remains as being less than 30,000 years old, confirming that these giant rhinoceroses also co-existed with humans.

The horn of E. sibiricum, like that of modern rhinoceroses, is made of keratin and so, like nails, it becomes broken down over time in a way that calcified tissue does not. As a result, we have no direct record of the size and shape of the horn (as far as I know) and must depend on assumptions based on features of the skull. The skull of E sibiricum has a large protuberance that is believed to have supported the horn and the News section of Nature [3] reported in 1878:

..the protuberance of the skull of the elasmotherium presents a rough, uneven surface, traversed by deep furrows once occupied by blood vessels. The whole analogy with the rhinoceros points with the greatest certainty to the previous existence of a horn, which, to judge from the size of the blood-vessels once encircling the base, must have possessed enormous dimensions, and easily exceeded the length of the skull itself.

Measurements taken by Shpansky et al. on the skull they examined gives the diameter of the protuberance, and thus the base of the horn, to be at least 26 cm across and all reconstructions of the Siberian Unicorn suggest a very large horn must have been present (see below).

Our knowledge of the appearance of animals that are reconstructed from fossil material comes from artists' impressions, based on the advice of experts in imagining whole animals from fossil fragments. We love these impressions, with many new finds, perhaps based on just a few pieces of skeleton, reported regularly by the media. We go further with animatronics and video techniques, showing movement and behaviour of extinct animals within their presumed environment. These are hugely popular, but are they always accurate?
Interestingly, large and/or dangerous extinct animals hold the greatest interest for us because they induce fear, an emotion that we enjoy at a safe distance. We recognise that there is a difference between myth and reality, yet the margin between the two can become blurred, especially when we let our imaginations have free rein. Having said that, wouldn't it be marvellous to discover a herd of living E. sibiricum, so that we know what they look like and how they behave?

[1] Philip Henry Gosse (1860) The Romance of Natural History. London, J. Nisbet and Co.

[2] Andrei Valerievich Shpansky, Valentina Nurmagambetovna Aliyassova and Svetlana Anatolievna Ilvina (2016) The Quaternary Mammals from Kozhamzhar Locality (Pavlodar Region, Kazakhstan). American Journal of Applied Sciences 13: 189-199.

[3] News (1878) The Elasmotherium Nature 18: 387-389