The Era of the Light Microscope

A comprehensive historical survey is found in WODEHOUSE (1935) and especially in DUCKER and KNOX (1985). Only the most important scientists can be mentioned here; the list is not exhaustive.

It was Nehemiah GREW who as early as 1662 in his famous work "The Anatomy of Plants" described the constancy of pollen form within the same species; in other words, he founded pollen morphology and was the first to recognize that all plants have "their" pollen. Carl von LINNÉ (1751) first used the term pollen (in Latin). During the 18th and the early 19th centuries there was considerable progress on pollen and the understanding of pollination. For example, Joseph Gottlieb KOELREUTER (1766), together with Christian Konrad SPRENGEL, the founder of flower ecology, perceived the importance of insects in flower pollination and found for the first time that the pollen grain has an important part in determining the characters of the offspring.

SPRENGEL (1793) was the first to recognize pores and furrows in the pollen wall; he also demonstrated the effects of cross pollination, of dichogamy, and distinguished between entomo- and anemophily.

Johannes PURKINJE (1830) and Franz Andreas (Francis) BAUER, among others, also made substantial contributions. BAUER is famous for his fine and exact drawings and watercolors of pollen, now held in the Botanical Library of the Natural History Museum, London. Only a few facsimiles have been published, e.g., in KESSELER and HARLEY (2004). Robert BROWN (1828, 1833) reported and confirmed BAUER's earlier work, and gave the first description of the origin of the pollen tube.

New and better microscopes enabled Hugo von MOHL (1834) and Carl Julius FRITZSCHE (1837) to separate clearly the principal layers of the pollen wall and to publish surveys on pollen morphology of many angiosperm families. The terms pollenin, exine and intine go back to FRITZSCHE. Johann Heinrich Robert GOPPERT (1837) and Christian Gottfried EHRENBERG (1838) were the first to describe and depict fossil pollen grains. Eduard STRASBURGER (1882) achieved ground-breaking insights into the development and internal structure of pollen. Hugo FISCHER (1890) was the first to summarize the arguments for the phylo-genetic value of pollen characters. Pollen statistics represented a first step towards an applied field of science and in 1916 Lennart von POST published the first pollen diagram (pollen profile).

The 20th century up to ca 1960 was dominated by the skilful use of the LM, with many new findings;for example, the LO-analysis, a method for analyzing patterns of exine organization by light microscopy: focusing at different levels distinct features appear bright (L = Lux) or dark (O = Obscuritas). Textbooks by Roger WODEHOUSE (1935), GunnarERDTMAN (1943, 1952, 1969), or Knut F^GRI and Johannes IVERSEN (1950) summarized the knowledge on pollen at that time and to a great extent have maintained their value.

In the first half of the 20th century paly-nology as a predominantly basic science "went applied", giving rise to a series of diversifications. Applied fields, worldwide in use, include aeropalynology, biostratig-raphy, copropalynology, cryopalynology, forensic palynology, iatropalynology, melisso-palynology, paleopalynology, pharmaco-palynology, among others.

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