Bernstein, Julius

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(b. Berlin, Germany, 8 December 1839; d. Halle, Germany, 6 February 1917). phiysiology.

Bernstein was the son of Aron Bernstein, a Jewish theologian, author, and politician from Danzig. The father himself established a reputation as a popularizer of science, and it was under his influence that Bernstein early became interested in the natural sciences. While still a schoolboy he sought to solve physical and technological problems. In 1858 he began to study medicine at the University of Breslau, where his admiration for Rudolf Heidenhain turned his interest to physiology. Through the intervention of his friend Ludimar Hermann, Bernstein entered the laboratory of Emil du Bois-Reymond at Berlin, and he earned his medical degree there in 1862 with a dissertation on invertebrate muscle physiology. In 1864 Bernstein went to Heidelberg as assistant to Hermann von Helmholtz, whose sober outlook, dominated by the ideals of mathematical physics, corresponded well with Bernstein’s own temperament as a researcher. When Helmholtz was called to the chair of physics at Berlin in 1871, Bernstein became acting head of the Heidelberg Physiological Institute, but in the same year returned to Berlin. In 1872 Bernstein succeeded Friedrich Goltz as professor of physiology at the University of Halle, where he remained until his death forty-five years later.

Despite considerable difficulties, Bernstein succeeded in establishing a new physiology institute at Halle, but not a modern institution with separate departments for research and teaching. He made effective use of the very modest means at his disposal. Although it was not his ambition to form a school, he attracted the attention of many physiologists through the originality of his writings. His scientific interests and skills transcended physiology to include mathematics and astronomy.

Bernstein married the daughter of H. Levy, a Russian military physician. She took an interest in his work and shared his love of music. Their son, the mathematician Felix Bernstein, became well known in medicine for his computations of the inheritance of blood groups, Bernstein died of pneumonia at the age of seventy-seven.

During his long career Bernstein carried out important research. As creator of the “membrane theory of excitation,” he has a claim to a major place in the development of modern physiology, a fact that seems not to have been sufficiently appreciated during his lifetime. His works treated such broad areas of physiology as bioelectricity, structural problems of contractile substances, cardiac and circulatory physiology, reproduction and growth, secretion and resorption, respiration, sensory physiology, and toxicology. He was also concerned with the teaching of natural sciences. Evidence of his outstanding gifts in this area is his Lehrbuch der Physiologic des tierischen Organismus (1894; 3rd ed., 1908). Used in the training of physicians, it also influenced many young researchers in their choice of specialization.

Of particular interest are Bernstein’s contribuions to the physiology of irritable structures —that is, general nerve and muscle physiology and membrane physiology. His research in this field—to which he devoted the majority of his 135 publications—may be divided into two phases. In the earlier one, that of classical electrophysiology, he was concerned above all with perfecting techniques of stimulation and measurement. For example, an experiment demonstrating the simultaneity of the propagation of the excitation (wave) and the alteration of the electrical potential in nerves (1867) belongs to this period, So does his determination (the first) that synapse time for the neuromuscular junction is 0.3 milliseconds (1882). Bernstein also very ingeniously measured the velocity, form, and course of the excitation wave with the help of his differential rheostat. With this apparatus he was able— by employing periodic stimulation and by recording point by point small portions of the current curve-to reconstruct the entire course of the curve with the aid of his slowly reacting galvanometer. This painstaking technique permitted him to describe the real time course of the excitation process. In 1912 Bernstein recommended the use of the inertialess cathode ray for the record of bioelectrie activity, a suggestion that was taken up in physiological research, about a decade later, by Erlanger and Gasser.

Recohnizing that no further explanation of the nature of the excitation process could be expected from existing views and conventional methods, Bernstein turned to ideas and techniques of modern electrochemistry, molecular physics, and thermodynamics. The second phase of his research began with his application of these experimental tools to unresolved problems. Bernstein’s essential conceptual breakthrough was the assumption that even before stimulation, the cell membrane includes an electrically charged double layer of ions. According to this view, those ions that do not pass through are decisive in determining the differences in electrical potential between the two sides of the membrane, This idea was developed in the notion proposed by R. Höber (1873 - 1953) of selective permeability of the membrane and in his remarks on the role of salts in affecting the porosity of the membranes.

According to Bernstein, upon stimulation, the membrane’s permeability increases as a result of a chemical change, so that the excited portion becomes negatively charged with respect to the unexcited portion. That is, the membrane’s potential decreases upon stimulation. This alteration of the living substance propagates in the fiber in a wavelike manner and has a certain duration at every point along its course. It is the origin of the electric excitation wave (Aktionspotential, in Hermann’s terminology). “A consequence of this theory would be that the negative deflection (or oscillation) must attain a maximum, which would be given by the strength of the membrane’s potential, so that the latter could not be reversed during stimulation” (Bernstein, Elektrobiologie, 105). According to H. Grundfest, Bernstein thus sacrificed on the altar of his theoretical views the “overshoot” of the axon spike that he had observed as early as 1871.

It is worth noting, however—as E. Abderhalden stressed—that from the perspective of the history of science, Bernstein completed the conceptual and methodological restructuring of “his research at an age when most scientists are either reluctant to seek new paths or incapable of following them. His strict adherence to the methods of exact research, whether in classical electrophysoalogy or in the new thermodynamic treatment of bioelectrical phenomena, demonstrated the futility of speculative nineteenthcentury Naturphilosophie and argued strongly for what he himself called the “mechanistic theory of life” (1890).


I. Original Works. A chronologically ordered list of Bernstein’s publications (135 titles, plus 72 titles of works by his students) is in the article by A. von Tschermak (see below),


Berstein published the following books: Untersuchungen über den Erregungsvorgang im Nerven- und Muskelsystem (Heidelberg, 1871); Die fünf Sinne des Menschen (Leipzig, 1876; 2nd ed., 1889); trans. as The Five Senses of Man (New York, 1876); Die mechanistische Theorie des Lebens, ihre Grundlagen und Erfolge (Brunswick, 1890); Lehrbuch der Physiologie des tierischen Organismus (Stuttgart, 1894; 3rd ed., 1908); and Elektrobiologie. Die Lehre von den elektrischen Vorgängen im Organismus auf moderner Grundlage dargestellt (Brunswick, 1912).

His journal articles include “Über den zeitlichen Verlauf der negativen Schwankung,” in Pflügers Archiv für die gesamte Physiologie des Menschen und der Tiere, I (1868), 173-207; “Über den zeitlichen Verlauf des Poalrisationsstromes,” in Annalen der Physik und Chemie, 6th ser., 155 (1875), 177-211; “Über Ermudung und Erholung des Nerven.” in Pfüger’s Archiv, 15 (1877), 289-327; “Die Erregungszeit der Nervenendorgane in den Muskeln,” in Archiv für Anatomie, Physiologie und wissenschaftliche Medizin (1882), 329-346; “Neue Theorie der Erregungsvorgänge und elektrische Erscheinungen an der Nerven- und Muskelfaser,” in Untersuchugen aus dem physiologischen Institut der Universität Halle I (1888), 27-104; “Über das Verhalten der Kathodenstrahlen zueinander,” in Annalen der Physik, n.s.62 (1897). 415-424; “Chemotropische Bewegung eines Quecksilbertropfens. Zur Theorie der amöboiden Bewegung.” in Pfüger’s Archiv, 80 (1900), 628-637; “Untersuchungen zur Thermodynamik der bioelektrischen Ströme,” ibid., 92 (1902), 521-562, repr. in W. Blasius, I. Boylan, and K. Kramer, eds. Founders of Experimental Physiology (Munich, 1971); and “Kontraktilität und Doppelbrechung des Muskels,” in Pfüger’s Archiv. 163 (1916), 594-600.

Bernstein wrote brief evaluations of the scientific work of or, in some cases, obituaries of Paul du Bois-Reymond (1889), Helmholtz (1895, 1904), Carl Ludwig (1895), Emil du Bois-Reymond (1897), Frithiof Holmgren (1897), and Heidenhain (1897). He also became involved in polemics with Setchenov, Preyer, Engelmann, and Hermann. His “Errinerungen an das elterliche Haus” was printed in MS form in 1913.

II. Secondary Literature. See E. Abderhalden, “Dem Andenken von Julius Bernstein gewidmet,” in Medizinische Klinik 13, no. 9 (1917), 260-261; H. Grundfest,“Julius Bernstein, Ludimar Hermann and the Discovery of the Overshoot of the Axon Spike,” in Archives italiennes de Biologie, 103 (1965), 483-490; K. E. Rothschuh Geschichte der Physiologie Physiology, (Brelin-Göttingen-Heidelberg, 1953), trans. as History of Physiology, G. B. Risse, ed. (Huntington, N. Y., 1973); G. Rudolph, “Julius Bernstein (1839-1917),” in J. W. Boylan, ed., Founders of Experimental Physiology. Biographies and Translations (Munich, 1971), 249-257; A. von Tschermak, “Julius Bernsteins Lebensarbeit-zugleich ein Beitrag zur Geschichte der neueren Biophysik,” in Pfügers Archiv, 174 (1919), 1-89; and F. Verzar, “Erinnerungen an Julius Bernstein 1910/1911” (unpublished; for access to this paper write to G. Rudolph, Institut für Geschichte der Medizin und Pharamazie der Universität Kiel).

Gerhard Rudolph

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