Engelmann, Theodor Wilhelm

(b. Leipzig, Germany, 14 November 1843; d. Berlin. Germany, 20 May 1909)

physiology.

Engelmann was the son of the well-known bibliographer and publisher Wilhelm Engelmann and his wife, Christiane Therese Hasse, daughter of the Leipzig historian Friedrich Christian August Hasse. He was very musical and graduated from the Thomas Schule in Leipzig. In the winter semester of 1861–1862 he began his studies in the natural sciences and medicine at Jena, where he was introduced to comparative anatomy by Gegenbaur, to physiology by his brother-in-law, Adalbert von Bezold, and to botany by Schleiden. He continued his studies at Heidelberg and Göttingen, but it was at Leipzig that he finished his studies and in 1867 took his doctorate under the ophthalmologist Theodor Ruete, with a dissertation on the cornea.

At the beginning of 1867 Engelmann went to Utrecht, at Ruete’s recommendation, as assistant to the physiologist and ophthalmologist Franz Cornelis Donders. In 1869 he married Donders’ daughter, Marie. Following her early death he married Emma Vick, a well-known pianist whose professional name was Emma Brandes. Engelmann became associate professor of general biology and histology at Utrecht in 1871. In 1888 he was Donders’ successor in the chair of physiology, having declined offers of appointment from Freiburg im Breisgau, Zurich, and Jena, primarily because he suffered greatly from migraine headaches. In 1877 he was rector at Utrecht. Oxford conferred an honorary doctorate on him in 1894.

In the winter semester of 1897 Engelmann became professor of physiology at Berlin, succeeding Emil du Bois-Reymond. He not unhesitatingly exchanged his contemplative existence at Utrecht for the activity of the cosmopolitan city of Berlin. Senile diabetes and failing strength forced him to retire on 14 October 1908. He died the following year from progressive arteriosclerosis.

Engelmann became scientifically oriented at an extremely early age. He was a passionate botanist and microscopist while still a schoolboy. Before his dissertation (1867) he had already published eight papers in zoology and biology, especially on Infusoria, the connection between the nerves and the muscle fibers, and the excitability of nerves and muscles under the influence of induction currents. The microscope was also his most important research tool in Utrecht. Engelmann was one of the founders of the cell physiology that was widespread in the second half of the nineteenth century. In Utrecht (1869) he investigated the flagellating movements of protozoa in great detail and described the Flimmermühle and the Flimmeruhr, physiological devices for measuring oscillatory motion.

At the same time Engelmann began his studies on the transmission of stimuli in the muscles of the ureter and on the physiology of peristalsis. He was an energetic advocate of myogenic formation and conduction of stimuli (1869). He claimed the same thing for the heart and proved his claim with the famous “zig-zag experiment,” in which the heart of a frog was dissected spirally. In spite of its nerves being cut, the strip remained capable of forming and conducting stimuli (1875). Engelmann perfected the method of lever suspension with the frog heart and analyzed the laws of extrasystoles, the refractory phase, and the compensatory pause (1892–1895). He was the first to prove the lack of current in the intact and resting heart (1878) in opposition to du Bois-Reymond’s theory of the preexistence of the electrical charge in the intact and resting muscle fiber. Earlier he had determined the velocity of the conduction of stimuli in cardiac muscle (1875). He formulated the law of conservation of the physiological stimulus period (1895). Engelmann was the first to distinguish the four types of activity of the heart nerves: isotropic, bathmotropic, chronotropic, and dromotropic (1896). This was the final prerequisite, for an improved understanding of cardiac function in general and of the excitatory processed in particular.

Engelmann’s second main area of work was the physiology of muscle contraction, in which he made much use of the microscope. He described the diminution of double refraction in the contracted muscle fiber in polarized light (1873) and believed the cause of contraction to be a shifting of fluid from the isotropic to the anisotropic substance, suspecting swelling processes to be the cause. He constructed an artificial model of the muscle fiber (a birefringent violin string) in order to elucidate the contraction process, and believed that he was able to demonstrate that heat was directly transformed into mechanical work in the course of contraction (1893). A lively conflict of scientific opinion arose from this, a battle he finally lost.

A remarkable investigation with Genderen furnished the microscopic proof that the retinal cones of the frog shift in the course of the change from light to darkness (1884) and that such movements are binocular even if only one of the two eyes is illuminated. Finally, Engelmann analyzed the sensitivity of protozoa to light and color and chemotaxis in bacteria. He had a difference of opinion with Ranvier concerning the structure of the axis cylinder of peripheral nerves, since Engelmann (1880) had incorrectly believed that the nodes of Ranvier represented a discontinuity of the axis cylinder.

Engelmann’s interests were directed very early to microscopy and cellular physiology. At first, therefore, his subjects were more biological than physiological. Only with cardiac physiology did he enter the central area of experimental animal physiology. Engelmann never expressed himself on questions of theoretical biology or natural philosophy.

He lived a simple, modest, and retiring life. He loved music and musicians. His house in Utrecht and later in Berlin was frequently a meeting place for well-known musicians. He was an avid cellist and a close friend of Johannes Brahms, who dedicated the Quartet in B Major op. 67 to him. His correspondence with Brahms was published in 1918.

BIBLIOGRAPHY

l.Original Works. His publications usually appeared both in Dutch, in the archives in the Netherlands, and in German, particularly in Pflügers Archiv für die gesamte Physiologie and later in Archiv für Anatomie und Physiologie, of which he was editor from 1900 to 1909. Of his 245 publications (see the bibliography in Kingreen) only the most important can be listed here.

Engelmann’s books and surveys include Zur Naturgeschichte der Infusionsthiere (Leipzig, 1862); Über die Hornhaut des Auges (Leipzig, 1867), his inaugural dissertation;Über die Flimmerbewegung (Leipzig, 1868); “Physiologie des Protoplasma und der Flimmerbewegung,” in Hermanns Handbuch der Physiologie, I (Leipzig, 1879), 434–408; Uber den Ursprung der Muskelkraft (leipzig, 1892);Tafeln und Tabellen zur Darstellung der Ergebnisse spektroskopischer Beobachtungen (Leipzig, 1897); and Das Herz und seine Thatigkeit im Lichte neuerer Forschung (Leipzig, 1904).

His journal articles include the following, all in Pflügers Archiv für die gesamte physiologie: “Zur Physiologie der Ureter,” 2 (1869 243–293; “Die Hautdrüsen des Frosches,” 6 (1872), 97–157; “Mikroskopische Untersuchungen über die quergestreifte Muskelsubstanz,” 7 (1872), 33–71, 155–188; “Contractilität und Dopperbrechung,” 11 (1875), 432–464; “Über die Leitung der Erregung im Herzmuskel,” ibid., 465–480; “Flimmeruhr und Flimmermühle. Zwei Apparate zum Registrieren der Flimmerbewegung,” 15 (1877), 493–510; “Über das elektrische Verhalten des thätigen Herzens,” 17 (1878), 68–99; “Über die Discontinuität des Axenzylinders und den fibrillären Bau der Nervenfasern,” 22 (1880), 1–30; “Zur Anatomie und Physiologie der Flimmerzellen,” 23 (1880), 505–535; “Neue Methode zur Untersuchung der Sauerstoffausscheidung pflanzlicher und thierischer Organismen,” 25 (1881), 285–292; “Über Licht-und Farbenperception niederster Organismen,” 29 (1882), 387–400; “Über Bewegungen der Zapfen und Pigmentzellen der Netzhaut unter dem Einfluss des Lichts und des Nervensystems,” 35 (1885), 498–508; “Beobachtungen und Versuche am suspendirten Herzen. I,” 52 (1892), 357–393 (Suspensionsmethode); II, 56 (1894), 149–202 (Erregungsleitung); III, 59 (1895), 309–349 (Physiol. Reizperiode); and “Über den Ursprung der Herzbewegung...,” 65 (1897), 109–214.

Also see “Über die Wirkungen der Nerven auf das Herz,” in Archiv für Anatomie und Physiologie (1900), pp. 315–361; “Über die bathmotropen Wirkungen der Herznerven,” ibid. (1902), supp. 1–26; and “Über den causalen Zusammenhang zwischen Kontraktilität und Doppelbrechung (und ein neues Muskelmodell),” in Sitzungsberichte der Preussischen Akademie der Wissenschaften zu Berlin (1906).

II. Secondary Literature. Obituaries include Deutsche medizinische Wochenschrift, 35 (1909), 1110; R. du Bois-Reymond, in Berliner klinische Wochenschrift, 46 (1909), 1097–1099; Nederlands Tijdschrift voor Geneeskunde, 22 (1909), 1786–1790; H. Piper, in Münchener medizinische Wochenschrift, 56 (1909), 1797–1800; M. Rubner, in Verhandlungen der Physiologischen Gesellschaft zu Berlin, 34 (1910), 84–90; and M. Verworn, in Zeitschrift für allgemeine Physiologie10 (1910), i-vi.

Details of his life and assessments of his work may be found in Biographisches Lexikon der hervorragendsten Arzte..., I (Vienna-Berlin, 1932), 367; H. Kingreen, “Theodor Wilhelm Engelmann (Biobibliographie),” unpub., inaugural diss. (Münster, 1969); K. E. Rothschuh, Geschichte der Physiologie (Berlin-Göttingen-Heidelberg, 1953), pp. 213–214; and M Stürzbecher, “Beitrag zur Biographie von Th. W. Engelmann,” in Berliner medizinische Wochenschrift, 27 (1958), 470–474; and the article on Engelmann in Neue deutsche Biographie, IV (Berlin, 1959), 517–518.

K. E. Rothschuh