Nematoplexus - Where the spirals come from
deutsche Version

Nematoplexus wound tubesThe enigmatic "branch knots", scattered among the spiralling tubes of the enigmatic organism Nematoplexus seldom found in the famous Rhynie chert [1], have been thought to be places where the tubes branch profusely although a branching tube has apparently never been seen.

Fig.1: Spiralling tubes of Nematoplexus and two related "knots".
        Image width 1.3mm.

As seen in Fig.1 (reproduced from Rhynie Chert News 71 ), the tangle of randomly distributed tubes with dark "knots" in between is confusing, all the more so since straight or weakly curved tubes may also be present: Rhynie Chert News 51, 71 .

A region near the black spot on the right has been photographed anew with higher magnification and other illumination: Fig.2. (Note that Fig.2 is turned with respect to Fig.1.) What is seen here can tentatively be interpreted as follows: A small protruding part of the big black knot in the depth of Fig.1 on the right is seen on the left of Fig.2. By lucky coincidence, a small separate knot, not noticed in Fig.1 but now in the middle of Fig.2, is divided by a tilted crack plane reflecting the incident light so that half the knot, left of the divide, is illuminated from below while the other half, right of the divide, keeps in the shade. (The off-white angular mineral body can serve as a mark for comparison with Fig.1. The bright white spot below is an irrelevant light reflex from applied oil.) The colourful illumination of the tubes is due to a thin deposit of iron oxide on the reflecting crack face. Nematoplexus "knot"

Fig.2: Small "knot" incidentally divided by a crack in the chalzedony reflecting the incident light. Image width 0.3mm. Photograph by Gerd Schmahl.

Most interesting is the junction of an 11Ám-tube to what seems to be the indefinite surface of the knot: Contrary to the common belief due to the established term "branch knot", the tube is not produced by branching. The same can be expected from the other tubes. One tube right of the divide, for example, is wider than normal where it emerges from the knot.
In addition to the tube diameters of 10-12.5Ám in Fig.2, there is only one tube with 4Ám and a straight one with 17Ám. (More non-spiralling tubes are present at other places in this sample.)
Sample: Rh15/79, Part 4, obtained from Barron in 2014.

Finally it can be stated that there is evidence that the spiralling tubes
of Nematoplexus emerge from the so-called branch knots without any branching.

H.-J. Weiss     2018

[1]  A.G. Lyon: On the fragmentary remains of an organism referable to the nematophytales, Nematoplexus rhyniensis.
      Trans. Roy. Soc. Edinburgh 65(1961-62), 79-87, 2 plates.        (Scale error on Plate I Fig.1: not x19 but x1.5)
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