Wilhelm Pfeffer

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Wilhelm Friedrich Philipp Pfeffer (9 March 1845 - 31 January 1920) was a German botanist and plant physiologist who was born in Grebenstein. He studied botany, physics and pharmacology at the University of Goettingen under Friedrich Wöhler (1800-1882), William Eduard Weber (1804-1891) and Wilhelm Rudolph Fittig (1835-1910). Afterwards, he furthered his studies at the Universities of Marburg and Berlin. At Berlin he studied under Alexander Braun (1805-1877) and was an assistant to Nathanael Pringsheim (1823-1894). He later worked as an assistant to Julius von Sachs (1832-1897) at Würzburg. In 1873 he became a professor of pharmacology and botany at the University of Bonn. He later became a professor at the Universities of Basel (1877), Tübingen (1878) and Leipzig (1887). At Leipzig, he was also director of the botanical gardens.

With Julius von Sachs, Pfeffer is considered the founder of modern plant physiology. His scientific interests included the thermonastic and photonastic movements of flowers, the nyctinastic movements of leaves, protoplastic physics and photosynthesis. In 1877, while researching plant metabolism, Pfeffer developed a semi-porous membrane to study the phenomena of osmosis. The eponymous Pfeffer cell is named after the osmometric device he constructed to determine the osmotic pressure of a solution.[1]

During his tenure at Leipzig, Pfeffer published an article on the use of photography to study plant growth. He wanted to extend the chronophotographic experiments of Étienne-Jules Marey (1830-1904), by producing a short film involving the stages of plant growth. This "movie" would be filmed over a period of weeks by frame-at-a-time exposure taken at regular, spaced intervals. Later, time-lapse photography would become a commonplace procedure.[2]

[edit] Bibliography

Physiologische Untersuchungen - 1873
Lehrbuch der Pflanzenphysiologie (Textbook of Plant Physiology).
Die periodischen Bewegungen der Blattorgane - 1875
Beiträge zur Kenntniss der Oxydationsvorgänge in lebenden Zellen - 1889
Über Aufnahme und Ausgabe ungelöster Körper - 1890
Studien zur Energetik der Pflanze - 1892
Druck- und Arbeitsleistung durch wachsende Pflanzen - 1893
Untersuchungen über die Entstehung der Schlafbewegungen der Blattorgane - 1907
Der Einfluss von mechanischer Hemmung und von Belastung auf die Schlafbewegung - 1911
Beiträge zur Kenntniss der Entstehung der Schlafbewegungen- 1915
Osmotische Untersuchungen, unveränd. Aufl. - 1921