Reading good old stuff sometimes pushes you to the borders of your knowledge. So far, I’ve been learning about Liesegang rings recently. No, nothing close to blingy blingy gangsta jewelry actually. Something that has more to do with chemistry. Liesegang rings are a phenomenon of periodic precipitation resulting in circular patterns that impressed scientists a lot a while ago, to the point it came out not only as a physico-chemical process, but as an explanation for some biological phenomena as well. As far as I can tell read, no unifying grand theory of this Liesegang phenomenon made it completely yet, chemically speaking. The thing is, with regard to biology, it did not really stand as a process of any explanatory power, and it disapeared from the biological jargon.
But which kind of biological feature could result from such a process as periodic precipitation? Guess it! It’s this rather intriguing organization of fruiting bodies in molds. Somewhat concentric circles. Striking regularity. In case you don’t see what I mean, and wouldn’t play the “wait and see” game, here what I found at the bottom of a long lost cup of coffee. (Hum, this coffee is not green, but it’s sure alive!).
The fascinating and familiar concentric distribution of fungous fruiting structures and the alternate concentric zones of dense and less dense mycelial aggregates have been many times reported in the literature but the data concerning the elusive factors which control them are too fragmentary and inadequate for a general theoretic treatment. I t may be possible to relate the chemically produced Liesegang rings to the analogous appearances in fungi and other organic forms and to apply the explanations given for the Liesegang phenomena to the fungi. (Hein, 1930)*
There was an age in biology where a great hope was given to the “life as a crystal” concept. Biological organization and structure, or say, even development, had to be explained, and nothing would have made more sense than simple universal rules. It’s not that far ago, and it’s impressive how deeply this was in the airs and the minds. And I’ll let you discover the following ending paragraphs of this old paper:
Symmetry was recognized as an aesthetic principle by the ancients and its importance in art is everywhere known. The beautiful many-times figured radial and zonal patterns in fungi owe their aesthetic value to their symmetry. The widespread application of this principle in science generally has been most effectively pointed out by Jaeger (1920). In the structure of atoms in the molecule, the forms of crystals, the arrangement of leaves and branches, of floral organs, and of organic cells; everywhere the principle of symmetry finds expression. That radial growth may be due to morphaesthesia has been earlier pointed out (Koll, 1900; Hein, 1928). Symmetry may be thought of as an expression of morphaesthesia and since symmetry in organisms has often been shown to be the result of surface tensions (Thompson, 1917) or form tensions (Kiister, 1913) all symmetry relations may possibly be traced to this force. Millis (1918), in pointing out the importance of “the simple geometrical principle, ” raises the question whether “all life, growth, repair, decay, and dissolution: even all mind, intelligence, emotion, and all reasoning and thought” may not be intimately related to it.
Oh my, mind! So far. Though this might seem today a long way past, I like the passionnate tone of this old paper. There’s something about doing science that can’t be missed here: at some point, an idea will give you this wonderful feeling that you got it. And you’ll be… enthusiastic is not even strong enough. And it’s worth all the hard work you’ve gone through until everything becomes clearer.
* Illo Hein (1930). Liesegang Phenomena in Fungi.
American Journal of Botany, 17 (2): 143-151.
[I]” As far as I can tell read, no unifying grand theory of this Liesegang phenomenon made it completely yet, chemically speaking.”[/I]
Khm…
As far as I can tell, I have found this “grand unified theory” of Liesegang rings. Chemically speaking. :-)
Just take a look at the simulation results on my site, you have linked.
There is another biological (or rather medical) phenomenon which was recently conjectured to be related to Liesegang rings. This is Balo’s concentric sclerosis, a rare form of multiple sclerosis (or a closely related disease). This might even have a role to play in understanding multiple sclerosis itself. For more information see the web page of Vincent Calvez at http://www.dma.ens.fr/~vcalvez/.
[…] Liesegang rings Liesegang rings are a phenomenon which is widely known due to the work of Raphael Eduard Liesegang in 1896 although he was probably not the first one to make such a observation. An experimental set-up which can be used is the following. A Petri dish is covered with a layer of a gel containing potassium dichromate. Then a drop of silver nitrate solution is deposited at the centre of the dish. It is observed that over a period of hours coloured rings appear which are centred on the point where the drop of solution was. It turns out that similar observations can be made in many other chemical systems. Another typical set-up is to take a test tube filled with gel containing one chemical and put a solution of another chemical on top of the gel. In this case horizontal bands are produced. Part of the fascination of the Liesegang phenomenon is the striking visual patterns which accompany it. Of course it should not be forgotten that not everything which looks the same must have the same underlying mechanism. This kind of phenomenon appears to be widespread in chemistry and has also been invoked in connection with certain biological phenomena. See for instance the discussion and pictures of fungal growth in https://seedsaside.wordpress.com/2008/02/21/liesegang-rings/ […]
“In antique science “petrified fossil’s stones” are considered “jokes of nature”; similarly mechanistic science till today considers periodic precipitations or Lisegang fossils as very mysterious events.” In fact the formation of regular chemical patterns in oscillating reactions was a physical paradox for more than a century.As a matter of facts Liesegang rings (1), (2), are easily visible structures of self organization phenomena that develop spontaneously in a chemical reaction systems working far from equilibrium with a slow kinetic of the reaction. (3)Alternating series of regular precipitating zones demonstrates a not chaotic behavior of the development of bonding and not bonding rings in an stabilized oscillating Liesegang reactions as it is easily shown in natural –artistic structures like the Liesegang Rings in Agate. (4)
The dynamic of formation of rhythmic pattern of precipitates giving the growth of Liesegang rings in gel inert medium is very easily to reproduce in a test tube , in spite of this experimental reproducibility mechanistic science is no able to understand why Liesegang pattering develops through a series of “bonding” and “no-bonding” bands of space-temporal progressive ordering. (5)
Biblio on line
(1) – Liesegang Rings : http://www.insilico.hu/liesegang/; http://www.sas.org/tcs/weeklyIssues/2004-04-30/chem/
(2) – Raphael E. Liesegang (1869-1947) http://science.birkenheadschool.co.uk/middle/index.php?id=Liesegang%20Rings
(3) – Catalytic time : http://www.edscuola.it/archivio/lre/tempo_di_catalisi.htm (in italian)
(4) – Lisegang Rings in geology : http://irna.lautre.net/Tout-ce-que-la-nature-ne-peut-pas,150.html
(5) – Chemical bases : http://www.edscuola.com/archivio/lre/chemical_bases.htm
[…] https://seedsaside.wordpress.com/2008/02/21/liesegang-rings/ […]