VALENTIN, GABRIEL GUSTAV

(b Breslau, Prussia [now Wroclaw, Poland], 8 July 1810; d. Bern. Switzerland, 24 May 1883)

embryology, general and comparative anatomy physiology.

Valentin is usually known as Purkyně’s most important student, but he early cut his ties to his teacher and worked on problems of his own choice. The only child of Abraham Valentin, a silverware merchant and assistant rabbi in Breslau, and Caroline Bloch, Valentin was equally interested in languages and science as a student at the Maria Magdalena Gymnasium. A knowledge of Hebrew enabled him also to study the Talmud. This, together with the religious traditions observed in his parents’ home, instilled in Valentin a firm conviction in the beliefs of his forefathers.

At the age of eighteen Valentin began to study medicine at the University of Breslau, where his most influential teachers were the botanist Nees von Esenbeck and the physiologist Purkyně. After four years he received his medical degree with a dissertation on the formation of muscle tissue, and he passed the state medical examination at Berlin in 1833. His father’s death obliged Valentin to begin practicing medicine immediately, in order to earn a living. He found greater satisfaction, however, in the time that he was able to devote to microscopic studies.

Perseverance, a gift for observation, and an outstanding memory were the foundations of Valentin’s wide-ranging scientific knowledge. A notable additional asset was his mathematical ability, which was of particular service to him in handling physiological problems. Valentin wrote more than two hundred papers and articles, as well as a number of books, some of which are quite long. Although his initial research centered on the formation of plant and animal tissue, he also was interested in the processes of intracellular movement in plants; and in his study of animals he was particularly concerned with embryology. he experimentally produced double malformations in chick embryos, on which he reported to the Versammlung Deutscher Naturforscher und Aerzte meeting at Breslau in 1833. The following year, Valentin undertook a study of the structure of nerve fibers in the brain and spinal cord, in particular measuring their thickness. This research, however, was hampered by a lack of sufficiently developed techniques.

In the spring of 1834, while conducting research designed to detect eggs in vertebrates, Valentin discovered the ciliated epithelium in the oviduct of rabbits; and with Purkyně he investigated its distribution in various classes of vertebrates. They also demonstrated the influence of chemical substances on the ciliary movement and ascertained that the movement is independent of the nervous system. The importance of this research was recognized in Valentin’s election to membership in the Leopoldinisch-Karolinische Deutsche Akademie der Naturforscher. Concurrently he wrote Handbuch der Entwickelungsgeschichte des Menschen … (1835) and worked on a prize question posed by the French Academy of Sciences in 1833: to determine whether the way in which animal tissues develop can be compared with that of plant tissues. In February 1835 Valentin submitted his answer to the Academy under the title “Histiogenia comparata.” This Latin manuscript runs to more than 1,000 quarto pages and includes many illustrations by the author.

In the summer of 1835 tensions developed between Valentin and Purkyně over their use of the same microscope in Purkyně’s house. Valentin thereupon sought to obtain an independent post. He received an offer from Dorpat: but there, and in Prussia, his Jewish faith proved to be a handicap. His situation soon improved, however; for in December 1835 the jury of the French Academy of Sciences awarded him the Grand Prix des Sciences Physiques for his histology manuscript. The prize, worth 3,000 gold francs, enabled Valentin to buy a large microscope and to travel to Berlin to see Johannes Müller. More important, however, he was recognized as an outstanding microscopist. He accepted a professorship of physiology and zootomy from the University of Bern, after making sure that he would not be required to abandon his religion. At the age of twenty-six Valentin became the first Jewish professor at a German-language university.

Valentin’s prize manuscript was not suitable for publication in the form in which he had submitted it, and he was asked to prepare a shortened version. He did not complete it, however, until the beginning of 1838, because of the time taken up by moving. The rapid advances in cytology during this period obliged him to take into account many new findings of other researchers, so that the shorter version no longer answered the original question; and for this reason it was not published. In fact, the essential contents of Valentin’s original manuscript were not published until more than a century later.

In his manuscript of 1834 Valentin designated the fundamental structural units of animal tissue as granula and globuli. Less frequently he called them corpora or corpuscula, but it is possible that these names refer only to the nuclei. Terms such as the granulosa of the ovarian follicle, the “grain” (Korn) layers of the cerebellum and of the retina, and the blood “corpuscles” recall the early years of the cell theory. Valentin provided good examples to illustrate cellular structure: the rudimentary form of the hoof (the blastema of the hoof of domestic animals) and fat cells, which he called cystae et contentum oleosum. The cysta is therefore the cytoplasm surrounding the fat globules. Valentin mentioned that in cartilage and bones he had seen traces of granules, by which he sometimes meant cells and sometimes their nuclei. (Volf mistakenly alleged that Valentin used the term “cell”as early as 1835, but the passage he cited as proof was actually from the shortened version of 1838.) The manuscript of 1835 does contain clear references to certain similarities between animal and plant tissues, but Valentin did not attribute special significance to them; they simply were not important to him. He even concluded from his study that the development of plant tissue is not comparable to that of animal tissue.

At Bern, Valentin had the use of a small but adequately equipped laboratory in the new anatomical institute. He continued to publish a periodical that he had founded at Breslau, Repertorium für Anatomic und Physiologie, which appeared from 1836 to 1843. The sole contributor, he reported the results of his own studies and surveyed the latest physiological literature. For example, from 1836 he used the term “cell” in describing many types of epithelium. Among the structural elements of the conjunctiva, he found nuclei and nucleoli: but he did not apply the term “nucleolus” to the latter, calling them, rather, “a kind of second nucleus within the nucleus.”

Valentin pursued his microscopic examination of the structure of nerve tissue with great enthusiasm. Since he clung to his notion of terminal loops of nerves and refused to recognize the occurrence of gray (marrowless) nerve fibers, he became involved in controversies with Johannes Müller and Robert Remak, as well as with Friedrich Heinrich Bidder and Alfred Wilhelm Volkmann.

Valentin also made comparative studies of the sea urchin and of the structure of the electric eel. For his research he devised a double-bladed knife for preparing thin sections, and he was the first to use microincineration in the study of animal tissue (bear spermatozoa in 1839). He also made a number of good observations of the structure of the eye, including the cornea and the ganglionic cells in the nerve fiber layer of the retina. His “Grundzüge der Entwicklung der tierischen Gewebe” is still worth reading.

In relation to his teaching duties, Valentin began to do more research in physiology. He designated the glossopharyngeal nerve as the chief nerve of the sense of taste, and he correctly assessed the effect of the electrically stimulated vagus nerve and of the sympathetic nervous system on stomach contraction. He also developed a highly respected method of determining blood volume, but it proved to be inexact. In extensive experiments on himself, Valentin studied the phenomenon of perspiration insensibilis (1843). He also ventured into the unfamliar fields of biochemistry and biophysics, but in the latter discipline his results were challenged by Emil du Bois-Reymond (1848).

While traveling to Bern, Valentin had made two lifelong friends during a stop at Frankfurt: Gabriel Riesser, a pioneer in the struggle for Jewish emancipation, and the Göttingen mathematqician Moritz Abraham Stern. He made other acquaintances in 1837 while in Paris, where, through the recommendation of Humboldt, he met Pierre Flourens, François Magendie, and Gilbert Breschet. In 1839 he traveled to Nice, where his most important contacts were with Rudolf Wagner. Valentin always welcomed visitors, among whom were Jacob Henle of Zurich and Adolph Hannover of Copenhagen.

Valentin was painstaking and conscientious, but he was more critical of the work of others than of his own. The letters that survive give conflicting images of his personality. He joined the Freemasons at an early date, and he was generous and–sometimes, at least–sociable. Occasionally he was boisterous or ironic; yet he himself was very sensitive, easily offended, sometimes mistrustful, and often dissatisfied. he was self-assertive in dealing with his colleagues and co-workers, and thus his relations with them were very strained at times. Valentin served several times as dean of the medical faculty; but despite more than forty years of teaching at Bern, he was never elected rector of the university.

In 1841 Valentin married his cousin Henriette Samosch; they had three children. Over the years the couple became increasingly estranged, and the children had to be sent out to board because of domestic difficulties.

In 1844 Valentin published the two-volume Lehrbuch der Physiologie des Menschen, an undertaking for which his previous study of the specialized literature for the Repertorium had prepared him well. A novel aspect of the Lehrbuch was the frequent attempt to treat problems mathematically. For example, Valentin mentions the then unknown diastasic property of pancreatic juice and reports his observations on the magnitude of the respiratory pressure (see Rothschuh [1952], pp. 13, 51). A second edition of the textbook soon proved necessary (1847-1850), and in it Valentin demonstrated the existence of the threshold of taste (Rothschuth [1952], p. 105). Valentin’s Grundriss der Physiologie des Menschen (1846), designed for both independent study and use with courses, went through four editions by 1855 and, like the Lehrbuch, appeared in several translations. These textbooks were replaced after about a decade of popularity by Carl Ludwig’s Physiologie des Menschen (1852-1856). Another important source for Valentin’s positions on contemporary problems was his reviews of the physiological literature in Canstatt’s Jahresberichte ü die Fortschritte der gesammten Medicin in allen Ländern (1844-1865).

The respect that Valentin enjoyed in Bern is evident in his becoming the first Jew to be granted citizenship by that city. His scientific standing is revealed not only in the visits by Henle and others but also in Alfonso Corti’s six-month stay at Bern in 1849 in order to learn microscopy from him. Corti, moreover, continued to consult with him until 1854.

As director of the Bern Anatomical Institute from 1853 to 1863, Valentin sought to make permanent the provisional arrangement under which it functioned, even though the trend elsewhere was toward a separation of anatomy and physiology. Younger colleagues, working under his supervision, took over part of the teaching in anatomy; but they were more held back than encouraged. Valentin had undoubtedly assumed too heavy a load of responsibilities, and he attempted to lighten his teaching duties in the laboratory courses by composing a pamphlet for students entitled Die kunstgerechte Entfernung der Eingeweide des menschlichen Körpers (1857). Of greater scientific significance were the studies he began at this time on the hibernation of the marmot (“Beiträge zur Kenntnis des Winterschlafes der Murmeltiere”), which merit an examination with the aid of the more exact techniques now available. Valentin’s Untersuchung der Pflanzen- und der Tiergewebe in polarisiertem Licht (1861) was subjected by W. J. Schmidt to a thorough analysis that will be of interest to specialists in the field. Schmidt also points out that Valentin made a number of innovations that contributed to the development of the microscope.

In January 1863 Valentin’s wife died after a long illness. At about the same time, the medical faculty sought to put an end to the union of the chairs of anatomy and physiology that he had imposed. Valentin, who was dean at the time, sought to maintain the status quo by appealing to higher authority, and he did not shrink from threats. The government, however, confined his responsibilities to physiology and named Christoph Theodor Aeby professor of anatomy. When the medical faculty declared in December that Valentin still had its support as dean, he allowed himself to be mollified and remained in office.

Until the fall of 1881, when a heart attack rendered him incapable of working, Valentin continued his scientific research, devoting these years primarily to polarization and spectroscopic studies. The results are recorded in “Histologische und physiologische Studien” (1862–1882). The series, which includes forty-five publications, was completed by four “Beiträge zur Mikroskopie” (1870-1875). Parallel with this research, Valentin made seven studies on the effects of curare and other arrow poisons, especially on muscles and nerves (“Untersuchungen über Pfeilgifte” [1868–1873]). The last fruits of his long research career are presented in twelve “Eudiometrisch-toxikologische Untersuchungen” (1876–1881).

Such extensive activity naturally brought Valentin many honors. In addition to being a member of the Leopoldinisch-Karolinische Deutsche Akademie der Naturforscher, he was a foreign corresponding member of the Académie Royale de Médecine de Belgique, of which he became honorary member in 1862. He was also a corresponding member of the Académie de Médecine of Paris; associate member of the Académie Royale des Sciences, des Lettres et des Beaux-Arts de Belgique: and honorary member of the medical societies of Stockholm, Erlangen, Hamburg, Budapest, Turin, Heidelberg, and Copenhagen, and of several scientific societies. The philosophy faculty of Bern awarded him an honorary doctorate, and he was presented with Festschriften on his jubilee dates.

BIBLIOGRAPHY

I. Original Works. Valentin’s earlier writings include Historiae evolutionis systematis muscularis prolulsio (Breslau, 1832), his dissertation: “Entdeckung continuierlicher, durch Wimperhaare erzeugter Flimmerbewegungen, als eines allegemeinen Phänomens in den Klassen der Amphibien, Vögel und Säugethiere,” in Johannes Müller’s Archiv für Anatomie, Physiologie, und wissenschaftliche Medicin, 1 (1834), 391–400, written with Purkyně Handbuch der Entwickelungsgeschichte des Menschen mit vergleichender Rücksicht der Entwickelung der Säugethiere und Vögel (Berlin, 1835): “De motu vibratoira animalium vertebratorum,” in Verhandlungen der Leopoldinisch-Carolinischen Akademie der Naturforscher, 17 Abt. 2 (1835), 841–854, writtten with Purkyně “Über den Verlauf und die letzten Enden der Nerven,” ibid., 18 Abt. I (1836), 51–240; De functionibys nervorum cerebralium et nervi sympathici libri quatuor (Bern– St. Gallen, 1839); and “Über die Spermatozoen des Bären,” in Verhandlungen der Leopoldinish-Carolinisschen Akademie der Naturforscher19 Abt. 1 (1839), 237–244.

Subsequent works are Valentin’s edition of “Hirn-und Nervenlehre,” in S. T. von Sömmering, Vom Baue des menschlichen Körpers, IV (Leipzig, 1841); “Beiträge zur Anatomie des Zitteraales (Gymnotus electricus),” in Neue Denkschriften der allgemeinen Schweizerischen Gesellschaft für die gesammten Naturwissenschaften, 6 (1842), 1–:74; “Grundzüge der Entiwicklung der tierischen Gewebe,” in Rudolf Wagner, ed., Lehrbuch der speziellen Physiologie (Leipzig, 1842); Lehrbuch der Physiologie des Menschen, 2 vols. (Brunswick, 1844) 2nd ed., 1847–1850); Grudriss der Physiologie des Menschen (Brunswick, 1846; 4th ed., 1855), translated into English as A Textbook of Physiology (London, 1853); Die kunstgerechte Entfernung der Eingeweide des menschlichen körpers (Frankfurt, 1857); and Die Untersuchung der Pflanzen-und der Tiergewebe in polarisiertem Licht (Leipzig, 1861).

Later works include “Beiträge zur Kenntnis des Winterschlafes der Murmelliere,” in Untersuchungfen zur Naturlehre des Menschen und der Tierre, 1–13 (1857–1888); “Histologische und physiologische Studien,” in Zeitschrift für rationelle Medicin, 3rd ser., 14–36 (1862–1869) and in Zeitschrift für Biologie, 6–18 (1870–1882); “Untersuchungen über Pfeilgifte,” in Pflüger’s Archiv für die gesammte Physiologie, 1–7 (1868–1873); “Beiträge zur Mikroskopie,” 581–597, 7 (1871), 140–156, 220–238, and 11 (1875), 661–687; and “Eudiometrisch-toxikologische Untersuchungen,” in Archiv für experimentelle Pathologie, 5–13 (1876–1881).

The MS of “Histiogenia comparata” is in the archives of the Paris Academy of Sciences. It has been published by M. B. Volf, in Věstnik Československé zoologické Společnosti, 6–7 (1938–1939), 476–512; and E. Hintzsche in Berner Beiträe zur Geschichte der Medizin und der Naturwissenschaften (Bern), no. 20 (1963).

II. Secondary Literature. See Erich Hintzche, “Gustav Gabriel Valentin (1810–1883),” in Berner Beiträe zur Geschichte der Medizin und der Naturwissenschaften (Bern), no. 12 (1953), with complete bibliography of Valetin’s writings; Bruno Kisch, “Gabriel Gustav Valentin,’ in “Forgotten Leaders in Modern Medicine,“in Transactions of the American Philsophcal Society, n.s. 44 (1954), 142–192; W. J. Schmidt, “Gabriel Gustav Valentin,” in Hugo Freund and Alexander Berg, eds., Geschichte der Mikroskopie, II (Frankfurt, 1964), 413–422; and Karl E. Rothschuh, Entwicklungsgeschichte physiologischer Probleme in Tabellenform (Munich-Berlin, 1952).

Erich Hintzsche