Jan Evangelista Purkyně

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Lore & Background

Purkyně was born in Libochovice in the Kingdom of Bohemia (then part of the Habsburg monarchy, now the Czech Republic). After completing senior high school in 1804, he joined the Piarists order as a monk but subsequently left "to deal more freely with science." In 1818, he graduated from the University of Prague with a degree in medicine, where he was appointed a Professor of Physiology. He discovered the Purkinje effect, the human eye's much reduced sensitivity to dim red light compared to dim blue light, and published in 1823 a description of several entoptic phenomena. He published two volumes, *Observations and Experiments Investigating the Physiology of Senses* and *New Subjective Reports about Vision*, which contributed to the emergence of the science of experimental psychology. He created the world's first Department of Physiology at the University of Breslau in Prussia (now Wrocław, Poland) in 1839 and the world's second official physiology laboratory in 1842. There he was a founder of the Literary-Slav Society. In 1850, he accepted the Physiology chair at Prague Medical Faculty, a position he held until his death. Purkyně is best known for his 1837 discovery of Purkinje cells, large neurons with many branching dendrites found in the cerebellum. He is also known for his discovery in 1839 of Purkinje fibres, the fibrous tissue that conducts electrical impulses from the atrioventricular node to all parts of the ventricles of the heart. Other discoveries include Purkinje images, reflections of objects from structures of the eye, and the Purkinje shift, the change in the brightness of red and blue colours as light intensity decreases gradually at dusk. Purkyně also introduced the scientific terms plasma (for the component of blood left when the suspended cells have been removed) and protoplasm (the substance found inside cells). He was the first to use a microtome to make thin slices of tissue for microscopic examination and was among the first to use an improved version of the compound microscope. He described the effects of camphor, opium, belladonna and turpentine on humans in 1829. He also experimented with nutmeg that same year, when he "washed down three ground nutmegs with a glass of wine and experienced headaches, nausea, euphoria, and hallucinations that lasted several days." Purkyně discovered sweat glands in 1833 and published a thesis that recognised 9 principal configuration groups of fingerprints in 1823. He was also the first to describe and illustrate in 1838 the intracytoplasmic pigment neuromelanin in the substantia nigra. He is also credited with the invention of the compressorium, a microscopy accessory to apply controlled pressure to specimens under observation. Purkyně also recognised the importance of the work of Eadweard Muybridge. Purkyně constructed his own version of a stroboscope which he called forolyt. He put nine photos of him shot from various sides to the disc and entertained his grandchildren by showing them how he, an old and famous professor, is turning around at great speed.

Reader's Guide

Jan Evangelista Purkyně was a foundational figure in several scientific fields. His coining of 'protoplasma' in 1839 helped define the basic substance of cells, a key concept in cell biology. His discoveries of Purkinje cells (1837) and Purkinje fibres (1839) advanced understanding of the nervous system and cardiac conduction. His work on sensory physiology, including the Purkinje effect and entoptic phenomena, contributed to the emergence of experimental psychology. He pioneered histological techniques by introducing the microtome and improving the compound microscope. His studies on drug effects (camphor, opium, belladonna, turpentine, nutmeg) and fingerprint classification (9 principal groups in 1823) were ahead of their time. He discovered sweat glands in 1833 and first described neuromelanin in 1838. He invented the compressorium and built a stroboscope called the forolyt. Purkyně's fame was such that letters from outside Europe addressed only 'Purkyně, Europe' reached him. His legacy includes the naming of a university in Ústí nad Labem (Jan Evangelista Purkyně University), a lunar crater (Purkyně), and an asteroid (3701 Purkyně) after him. His work remains influential in anatomy, physiology, and microscopy.

Did You Know?

• Purkyně coined the term 'protoplasma' in 1839 for the fluid substance of a cell.
• He discovered Purkinje cells in 1837 and Purkinje fibres in 1839.
• He was the first to use a microtome to make thin slices of tissue for microscopic examination.
• In 1823, he published a thesis recognising 9 principal configuration groups of fingerprints.
• He constructed a stroboscope called the forolyt, using nine photos of himself to entertain his grandchildren.