Friday, 16 December 2016

Parasol mushrooms, recipes and a great sadness

Parasol mushrooms (Lepiota procera – see above in an illustration by Mrs Hussey [1]) are striking and also delicious to eat. Although they are locally abundant, and easily collected, most of us buy mushrooms from supermarkets, or market stalls, as we know that some fungi are lethal to humans and we prefer to err on the side of caution.

In his book British Edible Fungi [2], Mordecai Cubitt Cooke is scathing about those who might confuse parasols with poisonous types:

The Parasol mushroom is known and appreciated throughout Europe, and is doubtless one of the first class for the table, with the great advantage that only dense stupidity could confound it with any suspicious species.

Cooke suggests that the Shaggy Parasol (Lepiota rhacodes), rather similar in appearance to L. procera, is also worth collecting and "there is no difference in their edible qualities". A few years back, I knew of some excellent patches of L. rhacodes and, accompanied by my son, Alex, we would collect enough for a good lunch on Sundays in October and November. We always cooked them sliced into hot butter, but Cooke gives several excellent recipes, many of which will have been familiar to cooks in the Nineteenth Century. At that time, collecting wild mushrooms was more popular than it is today, although Fungal Forays with an expert mycologist still attract good audiences.

Cooke's recipes [2] include the following:

Broiled Parasol Mushroom. - Remove the scales and stalks, and broil lightly over a clear fire on both sides for a few minutes; arrange them on a dish, over fresh made well-divided toast; sprinkle with pepper and salt, and put a small piece of butter on each; set before a brisk fire to melt the butter, and serve quickly.

Baked Parasol Mushroom. - Remove the scales and stalks, and place the caps in layers in a dish; put a little butter on each, and season with pepper and salt. Cover lightly and bake for twenty minutes or half an hour, according to the number in the dish. Put them on hot toast in a hot dish. Pour the hot sauce over them and serve quickly.

Stewed Parasol Mushroom. - Remove the stalks and scales from young specimens, and throw each one as you do so into a basin of fresh water, slightly acidulated with the juice of a lemon or a little good vinegar. When all are prepared remove them from the water, and put them into a stewpan with a very small piece of fresh butter, sprinkle with white pepper and salt, and add a little lemon juice. Cover up closely, and stew for half-an-hour. Then add a spoonful of flour with sufficient cream, or cream and milk, until the same has the thickness of cream. Season to taste, and stew again gently until all are perfectly tender. Remove all the butter from the surface and serve in a hot dish, garnished with slices of lemon. A little mace, nutmeg, or catsup may be added, if preferred, but some think the spice spoils the flavour.

Scalloped Parasol Mushroom. - Mince young fresh agarics, season with pepper, salt, and a little lemon juice, add a little butter, and stew in a warm oven for ten minutes, then put them in the scallop tin, layer by layer, with fresh bread crumbs moistened with milk, cream, or good gravy; bake for five minutes, and brown well before a quick fire.

Procerus Pie. - Cut the fresh agarics in small pieces, and cover the bottom of a pie dish. Pepper, salt, and place on them small shreds of fresh bacon, then put a layer of mashed potatoes, and so fill the dish layer by layer, with a cover of mashed potatoes for the crust. Bake well for half-an-hour, and brown before a quick fire.

Procerus Omelette. - Mince some young fresh agarics; season with pepper and salt; add butter and set them in the oven whilst you whisk well the whites and yolks of half a dozen eggs; then put two ounces of butter into the frying pan, and heat until it begins to brown; having again well whisked up the eggs, with three tablespoonfuls of the prepared agarics and a little milk, pour it lightly into the boiling butter; stir one way, and fry on one side only for five or six minutes; drain it from the fat; roll it up and serve quickly on a hot well covered dish.

In addition to these six, which you are no doubt very keen to try, there are also recipes for Parasol Sauce, Potted Procerus, Essence of Procerus and Procerus Ketchup, the latter two allowing Parasols to be enjoyed during the winter months.

We can imagine Cooke tucking into many feasts of these delectable mushrooms. However, we learn from his daughter, Leila [3], that he suffered badly from indigestion, something that he attributed to having eaten Norfolk dumplings when growing up (these dumplings were made from bread dough and were cooked in stews to add bulk). Leila relates that Cooke took a glass of ale and two Abernethy biscuits (advertised as being suitable for those with indigestion, and devised by a Dr John Abernethy) at 8 o'clock in the evening as he could not eat much [3].

Cooke was a renowned authority on fungi and worked at Kew for three days each week, otherwise identifying many specimens that were sent to him at home [3]. He also wrote more widely in Botany and was an illustrator, although he found it difficult to make money as a Botanist. He had a small pension from the India Office and, in his late eighties, moved to Southsea to be near his grand-daughters. Leila concludes her notes with this paragraph:

Arrived at Southsea, he could go and sit in the sun on the sea front, but in August 1914 war was declared; a bomb from the sea knocked down the garden wall. He could no longer go out. All around was the bustle of war. His grand-daughters were called up. He was a very lonely old man. On 12th November 1914 he died. He was buried in Finchley cemetery. Nobody came. The war was on.

This is so sad after the achievements of Mordecai Cooke and his splendid works on fungi, including his enthusiastic inclusion of recipes. His story becomes even sadder when one learns from Leila [3] that his collections of first editions, poems that he had written, an autobiography, and many other treasures were all destroyed during the Second World War, after an incendiary bomb attack on the repository where they were stored. Sad isn't a strong enough word – thank goodness we have British Edible Fungi to remember him by.

[1] Mrs T. J. Hussey (1847) Illustrations of British Mycology, containing Figures and Descriptions of the Funguses of Interest and Novelty Indigenous to Britain. London, Reeve Brothers.

[2] M. C. Cooke (1891) British Edible Fungi: how to distinguish and how to cook them. London, Kegan Paul, Trench, Trübner and Co.

[3] Mary P. English (2001) Leila Cooke's notes on the life of her father, M.C.Cooke. Mycologist 15: 91-93.

Tuesday, 6 December 2016

Edward Forbes and testable hypotheses

Although he was only 39 when he died, Edward Forbes had a lasting influence in Botany, Zoology and Geology, from both his published work, his lectures and his enthusiasm in supporting others. He had many friends and it is not possible to read the memoir by Wilson and Geikie [1] without feeling the affection in which he was held by fellow Natural Historians. As Daniel Merriman wrote, he must have been "a gentle lovely man"[2] as well as an eminent Professor.

In the field of Marine Biology, Forbes was a strong proponent of the use of dredges to scrape over the sea bed – an example of a dredge is shown above from the NOAA website (in an article that contains a typical poem by Forbes) [3]. He recognised the zonation of organisms on shores and identified the following zones after dredging studies of the Aegean Sea, each being characterised by different groups [1]:

He found that the [Aegean] could be sub-divided into eight provinces of depth; first, as around his own native islands, came the littoral zone, which, from the feebleness of the tides in those seas, did not exceed a range of two fathoms. The second region reached from 2 to 10, the third from 10 to 20 fathoms below the sea-level. The fourth region ranged down to 35 fathoms, the fifth from 35 to 55, the sixth from 55 to 80, and the seventh from 80 to 105. Each of these zones showed a marked and peculiar assemblage of living beings, and could even be further separated into sub-regions. The eighth region included all the space explored below 105 fathoms, and embraced a depth of 750 feet. It was an unknown tract – a new sea-country now added by Edward Forbes to the domain of the naturalist. In the lower zones, the number of species gradually diminished as the dredge sank towards the abysses. From 230 fathoms below the sea-level – the greatest depth Forbes reached – he drew up yellow mud with the remains of pteropods and minute foraminifera, and occasionally a shell. From a comparison of his observations, he conjectured that the zero of animal life would probably be found somewhere about 300 fathoms.

In their paper reviewing this azoic hypothesis [4], Anderson and Rice point out that there were several records of animals being taken from deeper water, even before Forbes dredged the Aegean. They conclude their paper with a section on the benefits of false hypotheses:

The controversy surrounding the azoic hypothesis was not so much due to problems with the theory itself, but rather the reluctance of many contemporary scientists to accept contradictory evidence. By proposing it, Forbes paved the way for later discoveries by stimulating the debate among leading naturalists of the day about how the marine environment influences the distributions of the plants and animals that live in it. For theories, including erroneous ones, are absolutely necessary for the advancement of science.

The acceptance of the azoic hypothesis reflected, in part the status of Forbes in the world of Natural History in the nineteenth century. However, his hypothesis was testable by further investigation and we now know that there is a fascinating, and sometimes abundant, fauna in the very deep regions of oceans.

Some scientific ideas are tricky, or even impossible, to test and those that involve very long time scales are typical of these. For example, conditions in hydrothermal vents provide physico-chemical conditions that promote the formation of the essential organic precursors of the first living organisms. Although we have only known about these vents for less than half a century, it is now possible to hear scientists give talks assuming that life on Earth began in hydrothermal vents, as though repetition of this "fact" establishes its truth. I'm convinced that evolution occurred, although I have no idea where, or how, life began, and I am convinced that the wide array of living organisms that we see around us, and the abundant examples of other life forms we know from fossils, all came about by mutation and selection. However, it is not possible to carry out experiments over time scales of millions of years to test my assumptions. We know that simple organisms that are abundant, and reproduce rapidly, undergo evolutionary changes over short time scales, and similar changes must occur, or have occurred, in multicellular organisms.
What is clear from the acceptance of Forbes' hypothesis is that we must be critical of established views, yet anyone proposing an alternative explanation will feel the weight of the scientific establishment at their back (ask James Lovelock). History shows that scientific explanations change with time and that must still apply – I wonder how many of our accepted theories, and non-testable hypotheses, will be accepted in the future?

[1] George Wilson and Archibald Geikie (1861) Memoir of Edward Forbes, F.R.S.: Late Regius Professor of Natural History in the University of Edinburgh. Cambridge, Macmillan and Co.

[2] Daniel Merriman (1963) Edward Forbes – Manxman. Progress in Oceanography 3: 191- 206.

[4] Thomas R. Anderson and Tony Rice (2006) Deserts on the sea floor: Edward Forbes and his azoic hypothesis for a lifeless deep ocean. Endeavour 30: 131-137.

Tuesday, 22 November 2016

"The human side of science"

In Glaucus, his book about the sea shore, Charles Kingsley writes [1]:

 ..few or no writers on Natural History, save Mr. Gosse, Mr. G. H. Lewes, and poor Mr. E. Forbes [who had died in 1854, at the age of 39], have had the power of bringing out the human side of science, and giving to seemingly dry disquisitions and animals of the lowest type, by little touches of pathos and humour, that living and personal interest to bestow which is generally the special function of the poet..

Certainly, both Gosse and Lewes were respected for their detailed, objective observations that we still value today, but, as Kingsley and many others discovered, they were also able to convey their enthusiasm for what they saw. However, they were not always in agreement. While recognising the importance of Gosse in popularising Natural History, Lewes challenged him over an observation on the defence mechanism of some sea anemones, to which Gosse responded (without mention of Lewes' criticism).

The events were these.

George Henry Lewes (above, upper) is less well known than his partner George Eliot (Marian Evans), justly famous as one of the finest novelists in the English language. She was encouraged in her writing by Lewes who was a polymath and, before Marian's success, was himself recognised as a scholar and biographer. Although fascinated by Natural History and Marine Biology, he was accused by T. H. Huxley of being a "book scientist" [2] and this spurred Lewes, accompanied by Marian, to collect, and observe, sea-shore life at Ilfracombe, Tenby, The Scilly Isles and Jersey. He wrote up his findings in Blackwood's Magazine in 1856 and 1857 and these accounts were then re-written, with additions, in his book Sea-side Studies at Ilfracombe, Tenby, The Scilly Isles, & Jersey, also published by Blackwood [3]. The choice of the first locations must have been influenced by Philip Henry Gosse (above, lower) who gave detailed descriptions of both Ilfracombe and Tenby in two of his earlier books [4,5].

Lewes makes reference to the work of Gosse throughout Sea-side Studies and acknowledges the usefulness of his scientific works and the importance of his more general, descriptive books in Marine Biology and microscopy [3]. However, Lewes takes Gosse to task on one point: the role of acontia. These are threads found in some sea anemones and they can be projected through the mouth and from pores in the body (see images below - courtesy of This is what Lewes wrote [3]:

Mr Gosse proposes to establish a new genus, named Sagartia.. ..including in it all those Anemones which.. ..possess an abundance of peculiar white filaments, visible to the naked eye, which are protruded from the pores of the body and the mouth, when the animal is roughly handled. These filaments are seen, on examination to be chiefly composed of "urticating [stinging] cells."..
..[Gosse] relates that he once saw a small fish in the convulsions of agony, with one of these filaments in its mouth; it shortly expired. It is a matter of surprise and regret that Mr Gosse, having once made such an observation, did not feel the imperative necessity of repeating and varying it, so as to be sure that death was not a mere coincidence. If the filament had the power which this single observation fairly seemed to suggest, nothing could be easier than to establish the fact by experiment. But, I repeat, no one has seen the necessity for the verification of an hypothesis so plausible; and Mr Gosse, like all his predecessors, was content with recording his observation, as if it carried the point. Not being so content, I tested it thus: After irritating a Dianthus till it sent out a great many filaments, I dropped a very tiny Annelid among them, and entangled it completely in their meshes. Yet lo! these filaments, which are said to possess so powerful a faculty of urtication that even vertebrate animals are killed by them, had no other effect upon a soft Annelid than that of detaining it in their meshes, from which it shortly freed itself and wriggled away unhurt.

Lewes was right to criticise if a general conclusion was being made from a single observation, although his manner of expression is a little blunt. Gosse must have read this and he describes his own experiments on acontia in Actinologia Britannica [6]:

With a razor I took shavings of the cuticle, from the callous part of my own foot, as from the ball of the toe, and from the heel.. ..I then irritated a S. parasitica till it ejected an acontium and taking up with pliers [a] shaving of the cuticle, allowed it to touch the acontium, which instantly adhered across its surface. I now drew away the cuticle gently, so as not to rupture the acontium, and examining it.. ..immediately saw dense groups of cnidæ [stinging threads], standing endwise on the surface,.. ..all discharged and inserted into the substance..

..As to the injection of a poison, it is indubitable that pain, and in some cases death, ensues even to vertebrate animals from momentary contact with the capsuliferous organs of the ZOOPHYTA.

Gosse then refers to the observation criticised by Lewes:

I have elsewhere recorded [in The Aquarium [7]] an instance, in which a little fish, swimming about in health and vigour, died in a few minutes with great agony, through the momentary contact of its lip with one of the emitted acontia of Sagartia parasitica. It is worthy of observation, that, in this case, the fish carried away a portion of the acontium sticking to its lip; the force with which it adhered being so great, that the integrity of the tissues yielded first. the experiments which I have detailed above, we have seen that this adhesion is effected by a multitude of [stinging threads], whose barbs resist withdrawal. So.. ..we can with certainty associate the sudden and violent death of the little fish with the intromission of barbed [stinging threads].

There it rests. What both Lewes and Gosse describe is a fascinating defence mechanism rather than a means of obtaining food. It is something that makes one wonder and to ask "How did that evolve?". Gosse, however, would explain it as an example of God's extraordinary Creation. In contrast, Lewes was an agnostic, so the publication of Darwin's Origin of Species in 1859 will have set his mind on trying to answer the impossible, yet fascinating, questions that we face today. There were many similarities between Lewes and Gosse, but clearly some important differences, and I'm not sure that they would have enjoyed each other's company, especially after the tone of Lewes' criticism. Perhaps I'm wrong?

[1] Charles Kingsley (1855) Glaucus; or, The Wonders of the Shore. London, Macmillan and Co.

[2] Ann Thwaite (2002) Glimpses of the Wonderful: The Life of Philip Henry Gosse 1810-1888. London, Faber and Faber.

[3] George Henry Lewes (1858) Sea-side Studies at Ilfracombe, Tenby, The Scilly Isles & Jersey. Edinburgh, William Blackwood and Sons.

[4] Philip Henry Gosse (1853) A Naturalist's Rambles on the Devonshire Coast. London, John van Voorst.

[5] Philip Henry Gosse (1856) Tenby: a sea-side holiday. London, John van Voorst.

[6] Philip Henry Gosse (1860) Actinologia Britannica. A history of the British sea-anemones and corals. London, John van Voorst.

[7] Philip Henry Gosse (1854) The Aquarium: an unveiling of the wonders of the deep sea. London, John van Voorst.

Thursday, 10 November 2016

Huxley's Bathybius – an early example of an organic aggregate

In a 1983 paper, the oceanographer Tony Rice offers an explanation for the appearance of Bathybius haeckelii, thought to have been a living organism by T.H.Huxley [1]. Rice writes [2]:

In the 100 years or so since Huxley's Bathybius was relegated to the status of an interesting but embarrassing error, knowledge of deep-sea biology has increased enormously, for many thousands of samples both from mid-water and from the deep-sea floor have been collected and examined. Consequently, although the deep ocean is still the least well-understood environment on earth because of its relative inaccessibility, some basic facts about its biological processes are now well-established...
.. With the exception of the minor local input from the activities of chemo-autotrophic bacteria, the food supply on which all deep sea animals are ultimately dependent originates in the near surface layers. In temperate waters, at least, the surface productivity is very seasonal, being highest in spring and summer when the phytoplankton is growing rapidly, and very low during the winter months. Although some of this material reaches the sea floor in the form of large, fast-sinking carcasses of fishes and whales, the main supply probably arrives as small particles, including the bodies of small plants and animals and faecal pellets, which may take many weeks to sink through the water column.

We now know that the sinking material also contains large numbers of flocs and other aggregates bound by the exudates of both bacteria and algae [3]. It is these that give the appearance of fluff that can be found over the ocean floor and which are difficult to collect in dredges, but which are clearly visible in sediment traps [2].

All this is a bit technical.

In the simplest terms, what Huxley observed was a large floc that contained components from near-surface organisms; the conclusion of contemporary scientists being that it was a precipitate of calcium sulphate, caused by preservation of a sample of sea bed in alcohol. This put an end to questions about the organic matter that was also present and the our seeming need to focus on organisms, rather than on total organic matter, was also a problem. We continue this focus, rather than taking the whole package of living and dead organic matter into account.

Let me give an example. What do you see when you look at this image from NOAA [4]?

Most will see an interesting creature – a whiplash squid – and wonder about its biology and mode of life. What about all the white dots in the rest of the picture, illuminated like the particles visible in the beam of a cinema projector? Don't  these raise questions?

While we know more about these particles and aggregates than we did when Tony Rice wrote his article, we still tend to ignore them in favour of our interest in organisms. It is true that the organic matter present in oceans, and other water bodies, is largely dependent on organisms for its production [3], but we must always consider the whole organic, and inorganic, package when trying to understand the biology of water bodies. What a pity that way of thinking didn't start with Huxley's observations on Bathybius.  

[2] A.L.Rice (1983) Thomas Henry Huxley and the strange case of Bathybius haeckelii; a possible alternative explanation. Archives of Natural History 11:169-180.

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