Ilia Faddeevich Tsion

(also Cyon, Elie de). Born Mar. 13 (25), 1842, in Panevezhis, now in the Lithuanian SSR; died Oct. 23 (Nov. 5), 1912, in Paris. Russian physiologist.

Tsion graduated from the University of Berlin in 1864. He became a professor at the University of St. Petersburg in 1870 and at the St. Petersburg Medical and Surgical Academy in 1872. Tsion directed the studies of I. P. Pavlov, the first physician to graduate with a specialization in physiology. In 1875, Tsion was forced to leave the academy because his extremely reactionary views brought him into conflict with the professors and students. That same year, upon C. Bernard’s invitation, Tsion moved to Paris, where he continued his work in physiology.

Tsion’s principal works deal with the physiology of blood circulation and the nervous system. He and his brother M. Tsion demonstrated experimentally the accelerating influence of sympathetic innervation on the heart. Tsion and the German physiologist K. Ludwig discovered the centripetal (depressor) nerve that proceeds from the arch of aorta and demonstrated that irritation of the nerve’s central ending causes a drop in blood pressure as a result of dilatation of the blood vessels (1866). Tsion discovered the nerves that accelerate the heartbeat, and he studied the influence of temperature changes, oxygen, and carbon dioxide on the rhythm and force of the heartbeat. Tsion also studied the changes in the excitability of the anterior radices of the spinal cord after the posterior radices have been severed. In experiments on an isolated liver he determined the organ’s role in the synthesis of urea and lipids. Tsion was the author of one of Russia’s first physiology textbooks (A Course in Physiology, vols. 1–2, 1873–74).