History of Palynology

HISTORICAL PERSPECTIVE p.1-2.

Spores and pollen are marvellous objects for study. Their morphology is infinitely varied, in a package so small that the wonder of their beauty never ceases to fascinate. This enchantment started as soon as the human eye was fortified by the magnifying property of the convex lens; without microscopes, there would be no palynology.

According to Bradbury (1967, q.v. for references in this paragraph), the Englishman N. Grew in 1640 was the first to observe pollen grains under a microscope. J. Wilson, in 1702, constructed microscopes with a screw focus that, in an article in the Philosophical Transactions, were referred to as "small pocket-Microscopes, which with great ease are apply'd in viewing Opake, Transparent and liquid Objects; as the Farina of the Flowers of Plants, etc.; the Animals in Semine, etc.". The screw device used by Wilson to bring objects into focus was invented by A. van Leeuwenhoek, who in the 1680s wrote a series of letters to the Royal Society on his "Animalcules" red blood corpuscles, protozoans, yeast cells, etc. [Dobell's (1960) fascinating translations accurately and engagingly reflect the earthy quality of the original Dutch]. However, van Leeuwenhoek's "glasses" were not true microscopes, but simple (i.e. not compound) convex lenses, with an extremely small working distance. By the early eighteenth century, microscopes with compound lenses were in use; E. Culpeper, for example, manufactured them, and in 1730 supplied samples of "The down of a Moth's wing. The dust of the Sun Flower. The dust of Mallows. The Eye of a Fly." to his customers.

By the following century the microscope had become a basic research tool, and was eventually applied in the first research on fossil spores. R. Kidston (in Bennie & Kidston 1886, q.v. for references in this paragraph) wrote that "the occurrence of spores in coal has been known for many years, though for a considerable time...they were considered as sporangia, and it is only within the last few years that their true nature has been understood." Kidston reviewed the then current state of affairs, starting with the first observation of spores in thin sections of Lancaster coal in 1833 by H. Witham who tentatively had interpreted them, however, as vessels of monocotyledonous plants. J. Morris (1840) described the "macrospores" of Lepidodendron (Lycopodites) longibracteatus as "thecae" or "capsules" preserved as organic matter. In 1848, H.R. Goppert designated some macrospores as Carpolithes coniformis; and O. Feistmantel (1881) described masses of macrospores under this name, even though he knew they were spores. These masses of megaspores commonly occur in a matrix of microspores, as was observed in thin sections. J.D. Hooker, in 1848, was the first to observe such microspores in situ, in sporangia of Lepidostrobus. A similar observation was made by W. Carruthers (1865), who described, as Flemingites, a Lepidostrobus cone with "macrospores," one per scale; however, as he did not observe the wall of the sporangium enclosing these spores, he took them to be sporangia. W.P. Schimper (1870) described a cone with both micro- and "macrospores" in situ, and a similar observation was published by E.W. Binney in 1871 on material of proven Carboniferous age. In the same year W.C. Williamson wrote the first of a series of publications demonstrating the presence of spores, either dispersed or still contained in their parent sporangia, and in 1872 he described in detail the "macrospore" later named Lagenicula.

Reinsch (1881) discovered, in Carboniferous, Permian and Triassic coals, organically preserved plant remains that were comparable to modern equivalents. He first studied them in 1200 thin sections prepared by a new technique. In 1884 he described, still in Latin, methods of extracting spores from Russian coal samples with concentrated KOH and HF, as well as a mixture of KC10~ + HNOz (Schulze's reagent, specifically formulated, in 1855, to disintegrate coal). He found immense numbers of spores comprising 80% of some samples! and published the first photomicrographs of fossil spores. He compared their shape and size with those of six species of modern Lycopodium, two of Selaginella, nine of Equisetum, and 63 of Filices, most of which were collected from documented herbarium sheets. By inference from these modern analogues, he calculated the spore production per plant, assigned his fossil forms to cryptogams, Lepidodendron and Filices, and estimated that they represented over 600 extinct plant species. Reinsch designated his "species" by numbers, and thus did not contribute to the nomenclature of fossil spores, other than by coining the generic name Triletes [which was validated by Bartlett (1929)]. He did describe assumed parasitic growths on the large megaspores, as an incertae sedis group Stelidae, with several genera; these entities were correctly interpreted as the sculptural elements of "macrospores" by Kidston (in Bennie & Kidston 1886, p. 87).

Kidston (1.c., p. 88) stated that "macrospores" of the type found in Lepidodendron [described as Sporangites glabra and S. papillata by Dawson (1868)] also may be found in Sigillaria. This had been postulated in 1855 by F. Goldenberg on disjunct material, and proved by R. Zeiller in 1884. Kidston described the two wall layers of these megaspores (exosporium and endosporium), and refuted a contemporary opinion that any original cellular structure of the wall, or the original spore content, would not have been preservable. Kidston noted that these spores were often found still attached in tetrads, thus proving their spore nature. Bennie & Kidston (1886) used these spores to characterize and correlate individual coal beds. Kidston's descriptions of the spores are clear, concise and comprehensive, better than many provided in much later literature. He did not use binomial nomenclature, but designated his taxa by numbers: "Triletes I" through "Triletes XIII", and "Lagenicula I" and "II". These designations were still applied in the 1930s.

Reinsch and Kidston were not the only early pioneers. Sarjeant (1982, 1991, 1992) summarized researchby Ehrenberg, Mantell and White, the latter in the mid-nineteenth century describing, illustrating and naming organically preserved dinoflagellate cysts so well (both taxonomically and nomenclaturally) that his names are still used. In 1929, Bartlett reviewed Reinsch's work and its significance for later spore workers. Reinsch had accumulated a wealth of keen observations and exemplary illustrations, but his insufficient botanical background and isolation from botanists (he worked in Russia, and without peer review!) caused him to publish some erroneous interpretations that led to rejection of all his writings. Yet, his illustrations are not distorted by preconceptions, and leave no doubt that they represent spores, many of which now are named. Bartlett, following a suggestion of Seward (1910), validated the name Triletes for trilete (mega)spores, even while observing that Thiessen (1920, p.71) expressed vigorous opposition to the introduction of formal nomenclature for dispersed spores before their affinity to a paleobotanical genus had been demonstrated. Yet, as Bartlett pointed out, mycology then already carried "for present convenience" many names of form genera for fungi imperfecti. And, although Thiessen demonstrated that coals could be identified and correlated by their spore content, he did not suggest how such work could proceed easily without a convenient nomenclature for the spores.

These developments set the stage for the work of R. Potonie and his students, who in the early 1930s laid the foundation of what now is called paleopalynology (e.g. Potonie 1932, 1934; Ibrahim 1933). Potonie, the geologist son of a paleobotanist, was a pathfinder who, by publishing all the detours in his taxonomic adventures, may have contributed some confusion. However, he was unquestionably the leader in the development of a morphological system for the classification of dispersed spores (see Ch. 2, 8, 9).

In the U.S.S.R., Naumova (1939) developed a comprehensive framework for spore nomenclature that never was fully established due to the intervention of World War II. The nomenclature of Liuber & Val'ts (1941) was correct but poorly differentiated; their generic names eventually evolved into Potonie's subturmae. It is interesting to compare the line drawings of these early Russian works with those of Reinsch: there appears to be more than a coincidental similarity, and the sense of a tradition.

References cited in "HISTORICAL PERSPECTIVE"

Bartlett, H.H. 1929.
The genus Triletes Reinsch; Papers of the Michigan Academy of Science, Arts and Letters. 9: 29-38.

Bennie, J. and Kidston, R. 1886.
On the occurrence of sores in the Carboniferous Formation of Scotland. Proceedings Royal Physical Society of Scotland 9: 82-117.

Bradbury, S. 1967.
The Evolution of the Microscope. Pergamon Press, New York, 375 p.

Binney, E.W. 1871.
Binney, E. W. 1867-1875.
Observations on the Structure of Fossil Plants found in the Carboniferous Strata. Palaeontographical Society Monographs 89, 106, 111, 130, 256. 24 plates.

Carruthers W. 1865.
On Caulopteris punctata, Goepp. a tree fern from the Upper Greensand of Shaftesbury, in Dorsetshire. Geol. Mag. 2: 484.

Dawson, J.W. 1868.
Notice on some remarkable genera of plants of the coal formation. Canadian Naturalist (n.s.) 3: 362-374.

Dobell, C. 1960.
Antony van Leewenhoek and His "Little Animals"; a Collection of Writings by the Father of Protozoology and Bacteriology. Dover Publications, New York, 434 p.

Feistmantel O. 1881
The fossil flora of the Upper Gondwana system. Mem. Geol. Surv. India, Palaeontologia Indica Ser. II, XI, XII; 149 pp., 47 plts.

Goldenberg F. 1855
Flora saraepontana fossilis. Die Planzenversteinerungen des Steinkohlngebirgs von Saarbrken.

Goppert H.R. 1848
Uber das Vorkommen von Pollen im fossilen Zustande. Neues Jarbuch fur Mineralogie Geognosie, Geologie und Petrefaktenkunde 11: 338-340.

Grew, N. 1682.
The Anatomy of Plants: With and Idea of a Philosophical History of Plants. Rawlins, London 304 pp.

Hooker, J.D. 1848
The vegetation of the Carboniferous period as compared with that of the present day. Memoirs of the Geological Survey of England and Wales 2: 387-430.

Ibrahim, A.C. 1933.
Sporenformen des Aegirhorizonts des Ruhr-Reviers. Konrad Triltsch, Wurzburg 47 p.

Liuber, A.A. and Val'ts, I.E. 1941.
Atlas of microspores and pollen of the Paleozoic of the USSR; Trudy Vsesoiuznogo Nauchno-Issledovatel'skogo Gologicheskogo Instituta (VSEIGEI). 139.

Morris J. 1840.
A systematic catalogue of fill plants of Britain. Magazine of Natural History 4: 75-80, 179-183.

Naumova, S.N. 1939.
Spores and pollen of the coasl of the USSR. IGC XVI Session 1, p. 343-364.

Potonie, R. 1932.
Pollenformen aus tertiaren Braunkohl. Jahrbuch der Preussichen Geologischen Landesanstalt zu Berlin 52: 1-7.

_________ 1934.
Zur mikrobtanik des eozanan humidolis des geiseltals. Arbeiten aus dem Institut fur Palaobotanic und Petrographie der Bernnsteine 4: 25-125.

Reinsch, P. 1881. Neue Untersuchungen uper die microstruktur der steinkohle des carbon, der Dyas und Trias. Leipzig p. 1-124, pl. 1-94.

Sarjeant, W.A.S. 1982.
Joseph B. Reade (1801-1870) and the earliest studies of fossil dinoflagellate cysts in England. Journal Micropalaeontology 1: 85-93.

_________ 1991.
Henry Hopley White (1790-1877) and the early researches on chalk "Xanthidia" (marine palynomorphs) by Clapham microscopists. Journal Micropalaeontology 10: 83-93.

_________ 1992.
Gideon Mantell and the "Xanthidia." Archives Natural History 19: 91-100.

Schimper W.P. 1870.
Traite de paleontologie vegetale, ou, La floure du monde primitif dans ses rapports avec les formations geologiques t la flore du monde actuel Balliere Paris. vol. 2

Seward, A.C. 1910.
Fossil plants: a text-book for students of botany and geology. v. 2. Cambridge University Press, 192 p.

Thiessen, R, 1920.
Structure in Palaeozoic bituminous cols. United States Bureau Mines Bulletin 17: 1-296.

Williamson W.C. 1871.
On the organization o the fossil plants of the coal-measures, part I. Philosophical Transactions of the Royal Society of London 159: 477-510.

Zeiller R. 1884.
cones de fructification de Sigillares. Annalse de Sciences Naturales (6) 19.