Leuckart, Karl Georg Friedrich Rudolf

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Leuckart, Karl Georg Friedrich Rudolf

(b. Helmstedt, Germany, 7 October 1822; d. Leipzig, Germany, 6 February 1898),

zoology, parasitology.

Leuckart, whose father owned a printing plant, attended the Gymnasium in Helmsted. His uncle, Friedrich Sigismund Leuckart, who was professor of zoology at Freiburg im Breisgau, made a strong impression on him and awakened his love for zoology. As a student he collected insects and soon decided to become a zoologist. At this, period, however, he could do so only by obtaining a medical education, since added by Democritus. But Theophrastus attributed to there were no faculties of natural science. Consequently, in 1842 Leuckart began medical studies at the University of Göttingen. He soon came into contact with the distinguished zoologist Rudolf Wagner, with whom he formed a lifelong friendship. Wagner encouraged Leuckart to undertake independent research and made him an assistant in his institute in 1845, after Leuckart had passed the state medical examination. Leuckart’s dissertation (De monstris eorumque causis et ortu), published in the same year, won a university prize; and Wagner immediately gave him an additional post as his lecture assistant. At the end of 1847 Leuckart qualified as a zoology lecturer at Göttingen with a lecture entitled “Naturgeschicte mit besondere Berücksichtigung des Menschen und der Tiere.” The following year Leuckart went on his first scientific expedition, to the German North Sea coast to study marine invertebrates. His investigations led to the establishment of the phylum Coelenterata.

In 1850, at the age of twenty-eight, Leuckart was appointed associate professor of zoology at the University of Giessen, to which Justus von Liebig and the anatomist and embryologist Theodor Bischoff were attracting many young researchers. Leuckart took his place among this illustrations company and later called his years in Giessen the happiest and most scientifically productive of his life. Here he met his wife, the daughter of a royal privy councilor, and conducted the investigations (1850-1869)on human and animal parasites that brought him world fame. In 1869 Leuckart accepted an offer from the University of Leipzig to succeed Eduard Pöppig, who had distinguished himself mainly as a geographer and world traveler. The facilities at his disposal were at first inadequate, but in 1880 he was given a new zoological institute constructed according to his plans and furnished with laboratories, a museum, and a library. Zoologists from all over the world came to the institute as guest researchers. Leuckart’s outstanding skill as a teacher and his clear delivery brought him many students who later held chairs of zoology not only at German universities but also in England, France, Italy, Sweden, Russia, Switzerland, Japan, and the United States. The Festschrift published on his seventieth birthday includes contributions by more than 130 former students and co-workers.

Leuckart was named a privy councillor by the king of Saxony and was named awarded an honorary Ph.D. by the University of Giessen in 1861. He was an honorary member of the Imperial Academy of sciences of St.Petersburg and received the highest Prussian and Bavarian orders: Pour le Mérite für Künste und Wissenschaften and maximilianorden. In 1873 he became dean of the philosophical faculty and in 1877-1878 was rector of the University of Leipzig. His powers gradually diminished, and the accidental death of his son Rudolf, a very promising chemist, and a daughter, after a long illness, pained him deeply and affected his creative ability in his later life. He died of a stroke, following an attack of bronchitis.

Leuckart’s first scientific work, which he began in 1847-1848, was the division of Cuvier’s Radiata into Coelenterata and Echinodermata (terms of his own devising). The result marked the beginning of a new period of scientific zoology, that of animal systematics based on subtle morphological investigations. His division on subtle morphological investigations. His division of the Metazoa into six principal phyla—Coelenterata, Echinodermata, Annelida, Arthropoda, Mollusca, and Vertebrata—is still considered classic, although it provoked considerable opposition when it was first proposed. For example, in 1848 the physiologist Carl Ludwig greeted with sarcasm the morphological point of view that Leuckart presented in his first book, Über die Morphologie und die Verwandtschaftverhältnisse der wirbellosen Tiere: “It would have to be considered a good sign for German science if this book found no readers.” Against this, the distinguished anatomist Heinrich Rathke wrote to Leuckart: “I hope not only that [your publication] finds many readers but also—should this happen—that it will be considered a sign of German science.”

In Die anatomisch-physiologische Übersicht des Tierreichs, published jointly with Carl Georg Bergmann in 1852, Leuckart placed greater emphasis on the physiological approach that ultimately enabled him to discover the developmental process of many parasites. He was especially interested in the sexual organs of the lower animals and in parthenogenesis, as well as in polymorphism, a term he originated. This research was summarized in the article “Zeugung” in Rudolf Wagner’s Handwörterbuch der Physiologie (IV, 1853). Leuckart’s primary interest, however, was parasitology, a subject then being established. His studies of the pentastomum, Taenia, liver fluke, and, most notably, Trichina spirals were epoch-making. In opposition to Küchenmeister’s view, Leuckart was able to show that Taenia saginata occurs only among cattle and Taenia solium only among pigs.

In 1860 Leuckart and Friedrich Albert von Zenker simultaneously discovered the Trichina, and an unpleasant priority dispute began. Although Leuckart’s publication did appear shortly before Zenker’s there is no doubt today that Zenker made the decisive discovery first. Both works, following the initiative of Rudolf Virchow, led to the world’s first meat inspection law. Leuckart carried out fundamental investigations of the Acanthocephalata and of Onchocerca volvulus, an organism responsible for onchocerciasis, which is still epidemic in central Africa. Leuckart also established the protozoan class Sporozoa and the order Coccidia. Many of his conclusions, derived from detailed investigations, were not confirmed until after his death; among these was the course of development of the roundworm Ascaris lumbricoides and the tapeworm Diphyllbothrium latum, which was first clarified in 1916 but have been correctly predicted by Leuckart.

The fruit of Leuckart’s research in parasitology, the two-volume Die menschlichen parasiten und die von ihnen herrührenden Krankheiten, was never completed; the aging Leuckart did not find the strength to finish it. Nevertheless, it has become a classic of parasitology, along with Berichte über die Leistungen der niederen Thiere (founded by Carl Theodor von Siebold), which Leuckart edited from 1848 to 1879 and which is a valuable source of information for mid-nineteenthcentury zoological literature. Summing up his life work, Leuckart wrote: “It is not possible for man, as a thinking being, to close his mind to the knowledge that he is ruled by the same power as is the animal world. Like the despised worm he lives in dependence upon external commands, and like the worn he perishes, even when he has shaken the world through the power of his ideas.”


I. Original Works. A list of the 115 zoological species, genera, and orders that Leuckart named, as well as a complete bibliography of his scientific publications, is in O.Taschenberg, “Rudolf Leuckart,” in Leopoldina (1899) 63-66, 89-94, 102-112. His most important works are Beirtäge Zur Kenntniss wirbelloser Thiere written with Heinrich Frey ; Über die Morphologie and die Verwandtschaftsverhältnisse der wirbellosen Thiere (Burnswick, 1848); “Ist die Morphologie denn wrirklich soganz unberechtigt?” in Zeitschrift für wissenschafttilche zoologie,2 (1850), 271-275; Über den polymorphismus der Individuen oder die Erscheinugen der Arbeiitsteilung Überschit des Thierreiclrs (Stutgart, 1852), written with C.G. Bergmann; Die Blasenbandwürmer und ihre Entwicklung (Giessen, 1856); Untersuchungen über Trichina spiralis (Leipzig-Heidelberg, 1860; 2nd ed., 1866); Die menschlichen Parasiten and die von ihnen herrühenden Krankheiten, 2 vols. (Leipzig-heidelberg, 1863-1876; 2nd ed., 1879-1894 [completed by Gustav Brandes]; 3rd ed., 1886-1901), also translated into English (Edinburgh-Philadelphia, 1886); “Organologie des Auges. Vergleichende Anatomie,” in C.F. von Graefe and E.T. Saemisch, eds. Handbuch der gesamten Augenheilkunde, II (Leipzig, 1875),pp. 145-301; and “Zur entwickklugegeschichte des Leberegels,” in Archiv für Naturgeschichte,48 (1882), 80-119.

II. Secondary Literature. See R.Blanchard, “Notices biographiques: Rodolphe Leuckart,” in Archives de parasitologie,1 (1898), 185-190; O.Bütschli, “Die wichtigsten biographischen Daten aus dem Leben Rudolf Leuckarts,” in Zoologisches Zentralblatt,6 (1899), 264-266 ; J. V. Carus, “Zur Erinnerung an Rudolf Leuckart,” in Sitzungsberichte der K. Sächsischen Gesellschaft für Wissenchaften, Mathphys. K1. (1898), 49-62; C. Grobben, “Rudolf Leuckart,” in Verhandlungen der Zoologische-botanischen Gesellschaft in Wien48 (1898, 241-243; L.Grosse, “Leuckart in seiner Bedeutung fur Naturund Heilkunde,” in Jaheresberichte der Gesellshaft für Natur-und Heilkunde in Dresden (1898). 93-96; R. von Hanstein, “Rudolf Leuckart,” in Naturwissenschaftliche Runsschau,13 (1898), 242-246; A Jacobi, “Rudolf Leuckart,” in Zentrablatt für Bakteriologie Parasitenkunde, infektionskrankheiten und Hygiene, 1st Section, 23 (1898),1073-1081; H.A. Kreis, ’ Rudolf Leuckart, der Begrgünder der modernen parasitologie,’ in CIBA-Zeitschrift (Basel), 5 (1937), 1755-1757; G. Olpp, Hervorragende Tropenärzte in Wort und Bild (Munich, 1932), pp. 236-240, an sepecially detailed biography; and the unsigned “Rudolf Leuckart,” in Nature,57 (1898), 542.

H. Schadewaldt