Koelliker, Rudolf Albert von

(b. Zurich, Switzerland, 6 July 1817; d. Wiirzburg, Germany, 2 November 1905)

comparative anatomy, histology, embryology, physiology.

Koelliker’s father, Johannes Koelliker, was a bank officer; his early death left his widow, Anna Maria Katharina Füssli, responsible for the education of their two sons. The family was of the upper middle class, with strong ties to letters and the arts. In his memoirs, published in 1899, Koelliker was to recall his carefree youth and his affection for his mother.

Koelliker attended the Gymnasium in Zurich, receiving supplementary private tuition in foreign languages. His interest in natural sciences, particularly botany, was early manifest and led him to study medicine when he entered the University of Zurich in the spring of 1836. His teachers included the botanist Oswald Heer; Lorenz Oken, whose lectures on zoology and Naturphilosophie he attended; and Friedrich Arnold, the anatomist, who instructed him in the basic tenets of the subject that he was to make his lifework. In 1839 Koelliker studied for a semester in Bonn; then, the following autumn, he went to Berlin, where he remained for three semesters. In Berlin he was strongly influenced by Johannes Müller’s lectures on comparative anatomy and physiology and was instructed in microscopy by F. G. J. Henle. Robert Remak introduced him to the study of embryology. Koelliker was singularly fortunate in his teachers; and the course of his career was then determined.

In the fall of 1840, Koelliker, with his close friend Naegeli and two other Swiss students, undertook a journey to the islands of Föhr and Helgoland to collect and study seabirds and marine animals. He continued to do independent research; the following winter, having bought a microscope, he began to investigate the spermatozoa of invertebrates. In refutation of the parasitic theory, Koelliker recognized the origin of the spermatozoa to be in the sperm– producing cells and thereby deduced their cellular nature. For these investigations he was awarded the Ph.D. at Zurich in spring of 1841. He took the state medical examination there in the summer of the same year, and then went on to study the development of two types of fly larvae. His results on this subject formed the basis for his M. D. dissertation. He received the degree from Heidelberg in 1842.

At about the same time Koelliker became assistant to Henle, who had assumed the professorship of anatomy at Zurich in 1840; their association was to develop into a long and fruitful friendship. In summer of 1842, Koelliker made another expedition with Naegeli to investigate the flora and fauna of the Mediterranean at Naples and Messina. Returning to Zurich, he became Henle’s prosector; in 1843 a discourse on the development of invertebrates qualified him for the post of lecturer in the university. In 1844 Henle accepted an appointment at Heidelberg. His professorship in Zurich was divided between two successors, Koelliker becoming associate professor of physiology and comparative anatomy and continuing to lecture on embryology and general anatomy.

In 1844, too, Koelliker published his work on the development of the cephalopods, a continuation of his earlier investigations of Mediterranean fauna. He had also by this time begun his researches on nerve tissue and demonstrated, in a paper on relative independence of the sympathetic nerve system, that among the vertebrates certain ramifications of the nerve cells exist as medullary nerve fibers. With Henle, he studied the lamellar corpuscles, for which they introduced the name “Pacinian corpuscles.” The following year he published an important paper on single-celled animals, particularly the gregarines, and in 1846 he brought out his studies on the formation of mammalian red blood corpuscles, with special emphasis on their nucleus-bearing first stages. The latter work is notable in that there Koelliker discussed the formation of blood in the embryo, localizing the site of hematopoiesis in the liver. In 1846 he also studied the structure of the smooth muscles, he further recognized the cellular nature of such muscle fibers and ascertained their wide distribution throughout the body.

In 1847 Koelliker was called to the University of Würzburg as full professor of physiology and comparative anatomy. Before accepting this new post, he stipulated that he was also to be made professor of anatomy as soon as that chair became vacant; he duly received that appointment in 1849. He was assigned to teach courses on human tissues and organs, in preparation for the textbook, Mikroskopische Anatomie, that he planned to base on his own investigations. In 1848 he married Maria Schwarz, of Mellingen, Aargau; his mother came to join their household shortly thereafter.

It was typical of Koelliker’ method of working that he sought to verify, if not personally study, each subject treated in his textbooks. Often before publishing a general work, he brought out individual treatises on his observations of specific details. Thus, while working on the Mikroskopische Anatomie, Koelliker in 1849 published his important findings on the formation of the skull, in which he made a distinction between the preformed, cartilaginous structure and the bony plates that develop from the connective tissue. He further continued his investigations of the central nervous system, and published an article on the course of the nerve fibers in the human spinal cord the following year. This procedure brought him a reputation for detailed research; he maintained it by being wary of hasty generalizations.

The publication of Koelliker’s Mikroskopische Anatomie oder Gewebelehre des Menschen provides a good illustration of this wariness. The second volume, bearing the separate title Spezielle Gewebelehre, appeared in three parts, between 1850 and 1854; the first volume, projected as a general treatment, was never published. That Koelliker was at this time working toward a generalization may, however, be seen in the chapter “Allgemeine Gewebelehre” of the textbook Handbuch der Gewebelehre des Menschen of 1852. This chapter might almost be considered a draft for the planned larger work, since it contains, in addition to a section on cytology, both detailed and general descriptions of ten different tissues. It is interesting to note that in the second edition, published three years later, Koelliker enumerated only five kinds of tissue, while in the third edition of 1859, he dealt with four. All the tissues he wrote of bore the names still in use, with the important exception of the epithelium, which he called Zellengewebe—cellular tissue.

Koelliker was thus one of the first to utilize the cellular elements of tissue structure descriptively. Indeed, his breakthrough lay in presenting the study of tissue in terms of the cell theory. His Handbuch was translated and had many editions; by this means his classification of tissues became known and accepted throughout central Europe.

While his microscopical work was receiving wide currency, Koelliker continued to teach and do research in physiology. Among other projects he confirmed the existence of the musculus dilator pupillae (1855). The following year he published his findings on the effect of various poisons on nerves and muscles; he also demonstrated that electric current is produced by muscle contraction. In 1857, Koelliker brought out his study on the light organs of the lamprey, in which he cited the dependence of these organs upon the nervous system. He extended his studies of the spinal cord to the lower invertebrates in 1858.

At the same time, Koelliker continued to lecture on embryology, a subject that had been of interest to him since his student days in Berlin. There he employed the cell theory in interpreting the development of the embryo, as he also did in his histological studies of tissues. His early studies of spermatozoa—in which he emphasized their cellular nature—were important in helping him to achieve this viewpoint. By 1856, in an investigation of their motility in various organic and inorganic substances, he was able to predicate that the motion of flagella and that of the sperm is essentially the same, noting in particular that both become more mobile in alkaline solutions. In a further series of studies he demonstrated that the same types of developmental processes occur in both invertebrates and vertebrates, although he based his work on an inaccurate notion of fertilization. He viewed the egg as a single cell, and correctly regarded its segmentation as a continuous production of daughter cells, which he interpreted as material for the developing tissues and organs. Koelliker thus opposed Schwann’s doctrine of free-cell formation in the cytoblast, although he did not exclude it in every instance, and fully rejected it only in 1859.

For his lectures on embryology Koelliker made himself thoroughly acqauinted with the existing literature and also had illustratory drawings made from specimens that he himself had prepared. He further drew upon the findings that he had made in regard to specific organs—as, for example, his results on the eye, ear, spinal cord, brain, and the olfactory and sex organs. In this way he came to compile a vast amount of information on the subject, which he decided to gather into as comprehensive a work as possible. His first publication, Entwicklungsgeschichte des Menschen und der höheren Thiere (1861), represented a collection of his classroom lectures. A second edition, published in 1879, was so fully revised as to constitute an entirely new book, while an abridgment for students, Grundriss der Entwicklungsgeschichte des Menschen und der hüheren Thiere, appearing in 1880, required a second edition by 1884. Here again, as in his work on tissues, Koelliker sought to incorporate all new data, subject, in so far as was possible, to his own investigation and verification.

In 1864 Koelliker gave up the chair of physiology at Würzburg. Two separate departments were organized for the teaching of anatomy and embryology, one comprising systematic and topographical anatomy, and the other, comparative anatomy, microscopy, and embryology. Koelliker and his co-workers taught alternate courses in macroscopic and microscopic anatomy, including related lectures on ontogeny.

As part of his work on the development of the embryo Koelliker was led to consider the origin of species and the laws of heredity. Although he carried out no special researches in this field, he had, as early as 1841, suggested that a particularly important function of the cell nucleus—in addition to its participation in the metabolism of the cell—was its agency in the transmission of inherited characteristics. In 1864, Koelliker made known his objections to Darwinian natural selection, which he thought too teleological. He pointed out that variations in certain characteristics are more apt to appear suddenly than gradually, and he emphasized the significance of such abrupt changes, thereby closely foreshadowing De Vries’s theory of mutations.

Koelliker returned to his study of nerve tissue with a treatise on nerve endings in the cornea in 1866. His work on the central nervous system took a new direction after 1884, when he heard of Golgi’s discoveries and adopted his methods of research, extending them to a study of parts of the brain. Koelliker was thus able to make important contributions toward substantiating the doctrine of the neuron as the basic unit of the nervous system. (Some of his results were to be incorporated into the sixth edition of the Handbuch der Gewebelehre.)

In 1873 Koelliker took up the study of the processes involved in the absorption of bone. He identified the large multinucleated cells that are active in osseous absorption and removal and named them “osteoclasts.” His findings were published, with illustrations, in his memoirs (pp. 315-323). In 1884, the same year in which he espoused Golgi’s work on nerve tissue, Koelliker also rejected His’s embryological theories. Having stated his objections to His’s parablast theory, Koelliker lived to see himself proved correct. He took further exception—again correctly—to His’s notion that the processes involved in the formation of the embryo might be understood through the mechanical model of an unevenly stretched elastic plate.

In 1897 Koelliker retired from teaching, but not from research. In 1899 he demonstrated the presence of uncrossed fibers in the optic chiasm, while in 1902 he made further exact studies of the nuclei (which he named for his anatomy demonstrator Hofmann) of the avian spinal cord. In 1903, when he was eighty-six years old, Koelliker conducted investigations into the origin of the vitreous body of the eye. He had teatined his post as director of the microscopical institute until fall of 1902; three years later he died of a lung infarct.

In addition to his textbooks, Koelliker published about 300 separate items during his lifetime. A list of these appears in Ehlers’ memoir of him (“Albert von Koelliker. Zum Gedächtnis,” pp. x-xxvi); it is arranged chronologically, but lacks fully adequate documentation. Koelliker himself mentioned almost all his published works in his Erinnerungen aus meinen Leben of 1899. He was also the founder and, with Theodor von Siebold, the editor of the Zeitschrift für wissenschaftliche Zoologie, which has been issued continuously from 1848 to the present.

Koelliker was instrumental in the founding of the Physikalisch-Medizinische Gesellschaft of Würzburg; he was active in the Anatomische Gesellschaft, of which he was the first chairman and later honorary president; and he worked ceaselessly to promote the international cooperation of scientists. He was, as Waldeyer wrote (in “Albert von Koelliker zum Gedächtnis,” p. 543), a “member of all the learned societies for which his knowledge qualified him,” and received international recognition in the form of honorary degrees from the universities of Utrecht, Bologna, Glasgow, and Edinburgh, as well as numerous medals and special awards. He was also a knight of the Maximiliansorden für Wissenschaft und Kunst and thereby personally ennobled.

The effect of Koelliker’s work was widespread and long lasting. His books set high standards for subsequent texts in histology and embryology, and his students included Haeckel and Gegenbaur. During his tenure, Würzburg became an important center for medical education. He was the first to recognize the cellular nature of tissue and extended the cell theory into new areas; his extensive investigations of histogenesis and comparative tissue theory helped to establish histology as an independent branch of science. Cytology too became a subject for separate study after Koelliker pointed out the significance of the nucleus in the physiology of the cell and began to study cell structure in detail.

BIBLIOGRAPHY

I. Original Works.Koelliker’s most important scientific publications are Beiträge zur Kenntnis der Geschlechtsverhältnisse und der Samenflüssigkeit wirbelloser Thiere … (Berlin, 1841), his doctoral diss.; Observationes de prima insectorum genesi… (Zurich, 1842), his M.D. diss.; “Beiträge zur Entwicklungsgeschichte wirbelloser Thiere I. Uber die ersten Vorgänge im befurchteten Ei.” in Müller’s Archiv für Anatomie, Physiologie und wissenschaftliche Medicin (1843), 66-141; Entwicklungsgeschichte der Cephalopoden (Zurich, 1844); Die Selbständigkeit und Abhängigkeit des sympathischen Nervensystems… (Zurich, 1844); “Die Lehre von der tierischen Zelle,” in Zeitschrift für wissenschaftliche Botanik (1845), 46-102; “Ueber die Struktur und die Verbreitung der glatten oder unwillkür–lichen Muskeln,” in Mitteilungen der Naturforschenden Gesellschaft in Zürich,1 (1847), 18-28; “Uber den Faser– verlauf im menschlichen Ruckenmarke,” in Sitzungsberichte der Phsikalisch–mediznischen Gesellschaft zu Wurz– burg,1 (1850), 189-207; Mikroskopische Anatomie oder Gewbelehre des Menschen, II, Spezille Gewebelehre, 3 pts.(Leipzig, 1850-1854), vol. I never published; Handbuch der Gewebelehre des Menschen (Leipzig, 1852; 2nd ed., 1855; 3rd ed., 1859; 4th ed., 1863; 5th ed., 1867; 6th ed., 1889- 1902), translated into French (Paris, 1856;1872), English (London, 1853-1854; philadelphia, 1854), and Italian (Milan, 1856); “Experimenteller Nachwies von der Existenz eines Dilatator pubillace,” in Zeitschrift fur wis – senschaftliche Zoologie, 6 (1855), 143; “Physiologische Studien über die Samenflüssigkeit,” ibid.,7 (1856), 201-273; “physiologische Untersuchungen über die Wirkung einiger Gifte,” in virchows Arcdhiv für pathologische Anatomie, 11 (1856), 3-77; “Ueber die Leuchtorgane von Lampyris,” in Verhandlungen der pathologisch-medizinischen Gesellschaft zu Würzburg,8 (1857), 217-224; “Vor–laufiger Bericht uber den Bau des Rüekenmarkes der niederen Wirblthiere,” in Zeitschrift fur wissenschaftliche Zoologie,9 (1858), 1-12; Entwicklungsgeschichte des Menschen und der hoheren Thiere (Leipzig, 1882); 2nd ed., 1879), also translated into French (Paris, 1882); Grundriss der Entwicklungsgeschichte des Menschen und der höheren Thiere (Leipzig, 1880; 2nd ed., 1884); “Uber das Chias– ma,” in Anatomischer Anzeiger,16 supp. (1899), 30-31; “Weitere Beobachtungen uber die Hofmannschen Kerne am Mark der Vögel,” ibid.,21 (1902), 81-84; and “Uber die Entwicklung und Bedeutung des Glaskörpers,” ibid.,23 , supp. (1903), 49-51.

His autobiography, Erinnerungen aus meinem Leben (Leipzig, 1899), contains a bibliography and analysis of his works on pp. 188-396.

II. Secondary Literature. See E. Ehlers, “Albert von Koelliker. Zum Gedächtnis,” in Zeitschrift für wissen–schafitliche Zoologie,84 (1906), i–xxvi, with bibliography on pp. x-xxvi; and Wilhelm Waldeyer, “Albert von Koelliker zum Gedächtnis,” in Anatomischer Anzeiger,28 (1906), 539-552.

Erich Hintzsche