Johann Nathanael Lieberkühn
Biography of Johann Nathanael Lieberkühn
Johann Nathanael Lieberkühn was the son of Johannes Christianus Lieberkühn, a goldsmith. In order to comply with his father's wish that he pursue a career in theology, he attended the Halle Magdeburg Gymnasium, before entering the academy in Jena, where he studied mathematics, mechanics, and natural philosophy. Influenced by the physician-iatromathematician G. E. Hamberger (1697-1755), he went on to study chemistry, anatomy, and physiology with Hermann Friedrich Teichmeyer (1686-1744) and Johann Adolph Wedel (1675-1747).
Lieberkühn left Jena in 1733 and joined his brother in Rostock as a candidate to become preacher. However, it took him but a few sermons to choose further studies into what most interested him. His aptitude for scientific studies was recognised by Johann Gustav Reinbech (1683-1741), a Protestant theologician, who introduced him to the Prussian king, Friedrich Wilhelm I (1688-1740). The king released Lieberkühn from the career set by his father, who had died in the meantime, so that he could devote full time to science and medicine.
As a result of his earlier work at Jena, he was elected fellow of the Berlin Academy of Sciences before he returned to Jena in 1735. After his second period at Jena, Lieberkühn travelled and studied in other centres, including the Imperial Natural Sciences Academy in Erfurt, where its president, A. E. Buchner, made him a fellow. He then pursued further medical study, especially of anatomy and chemistry, at Leiden under Hermann Boerhaave (1668-1738), Bernard Siegfrid Albinus (1697-1770), Hieronymus David Gaubius (1705-1780), and Gerard van Swieten (1700-1772).
En route to Leiden, Lieberkühn had visited Amsterdam, where he saw a solar microscope similar to the one Gabriel Daniel Fahrenheit (1686-1736) made in 1736. In 1738 Lieberkühn invented a microscope to be used in illuminating opaque objects. It was based on the principle of Fahrenheit’s solar microscope, consisting of a small, concave, highly polished silver speculum, later termed a Lieberkühn, that provided intense reflection of the sun’s rays directly upon the object. The noted English microscope maker John Cuff (ca. 1708-1772) later adapted Lieberkühn’s model by adding a mirror to it which provided better control by reflecting the sun’s rays to the speculum and then to the object.
In 1739, Lieberkühn obtained his medical doctorate at the University of Leiden. He subsequently spent some time in London and, as a result of his excellent demonstrations of the intestinal contents of an experimental animal before the members of the Royal Society of London, Lieberkühn was made a fellow in 1740. That year he settled in Berlin, where he practiced medicine until his death at the age of 45.
In De fabrica et actione vollorum intestinorum tenuium hominis (1745), Lieberkühn for the first time described, in greatest detail, the structure and function of the numerous glands attached to the villi, appropriately called Lieberkühnian glands, as well as the structure and function of the villi found in the intestines. All of these were made comprehensible by the meticulous and skilful injections of a mixture of a wax, turpentine, and colophony or dark resin.
In order to explore the circulatory vessels, Lieberkühn devised special microscopes to view in greater detail the intricacies of fluid motion within the living animal. His microscopes were called "Wundergläser" by his contemporaries and in some cases were designed specifically for a given preparation. One of these was the anatomical microscope used for viewing the circulation in frogs. The specimen was attached to the body of the microscope, which consisted of two thin silver plates between which was placed a small lens and around which were arranged hooks to hold and manipulate the animal. The part of the animal to be observed was fixed over the lens.
His most significant contribution during his last sixteen years, when he lived in Berlin, grew out of his desire to expose and preserve the vascular tissues of various animals. He assembled a collection of over 400 items which consisted of three main types of anatomical preparations: those preserved in a transparent liquid; dry specimens injected and hardened; and injected preparations of minute pieces of tissue (especially lung) to be viewed under the microscope. After his death this collection was advertised by a Paris dealer named Mettra and eventually was broken up and sold to several museums, as were other instruments he had constructed, including pneumatic pumps, pyrometers, and air guns.
Lieberkühn combined a gift for observation with technical facility, enabling him to perfect the instruments and injections required to explore the most minute vascular structure of both living and preserved. He was survived by his wife, the former Catherine Dorothy Neveling, and a son and a daughter.