TIMIRYAZEV, KLIMENT ARKADIEVICH

(b. St. Petersburg, Russia [now Leningrad, U.S.S.R.], 3 June 1843; d. Moscow, U.S.S.R., April 1920)

plant physiology.

Timiryazev was the youngest of the seven children of Arkady Semenovich, director of the St. Petersburg customshouse, and Adelaida Klementevna, an Englishwoman. The Timiryazevs were fairly well-to-do, but after the father’s retirement their financial position changed sharply. A knowledge of foreign languages enabled Timiryazev to set himself up as a reviewer of the English press for the newspaper Golos and to help his family by doing literary translations.

Timiryazev was educated at home and in 1860 entered St. Petersburg University in the natural sciences section of the Faculty of Physics and Mathematics. In 1862 he was expelled for participating in student disorders. After a year he renewed his studies at the university, but only as an auditor. He continued his work as a translator and also published an article on Darwin’s Origin of Species (1864). For work on liverworts (1865) Timiryazev received a gold medal and the degree of Candidate of Sciences. After graduating he worked under Mendeleev in Simbirsk province, studying new methods of agrotechnology. He also carried out experiments in photosynthesis. In 1868, at the First Congress of Naturalists and Physicians. Timiryazev gave a report on air feeding and the use of artificial light. In the same year, on the recommendation of Beketov he was sent abroad “for preparation for the rank of professor.” In 1868-1870 he worked in Germany with Helmholtz, G. Kirchhoff, Bunsen, and Hofmeister; in France, he worked with Berthelot, J. B. Boussingault, and Claude Bernard. On his return to Russia, Timiryazev became a teacher of botany in the Petrov Agricultural and Forestry Academy (now K. A. Timiryazev Moscow Academy of Agriculture) defended his master’s dissertation on the spectral analysis of chlorophyll (1871), and became extraordinary professor at the academy. In 1875 he defended his doctoral dissertation on the assimilation of light by plants, and became ordinary professor. In 1877 Timiryazev was elected professor of anatomy and plant physiology at the University of Moscow.

Timiryazev’s career was marked by encounters with the government and in 1898 he was discharged as a full-time teacher from Moscow University. He did retain the management of the botanical laboratory. Only in 1917 was he restored to the title of professor at Moscow University, but because of illness he could no longer work in the department. Timiryazev ardently embraced the ideals of the October Revolution.

Timiryazev’s basic research was in plant physiology. In 1860’s he began important experimental and theoretical work on photosynthesis. In his master’s and doctoral dissertations, and also in a series of later works he first used spectral analysis to study thoroughly the optical properties of chlorophyll and the dependence of photosynthesis on those properties of chlorophyll and on various rays of the solar spectrum. Timiryazev refuted the incorrect opinion that maximum photosynthesis occurs in the yellow-green rays and showed that the process proceeds most intensively in the red part of the spectrum. He substantiated the applicability of the first law of photochemistry and the law of the conservation of energy to the process of photosynthesis.

Timiryazev developed the concept of chlorophyll not only as a physical but also as a chemical sensitizer immediately affected by the oxidation reduction transformation in the course of photosynthesis. In 1890 he was one of the first to assert the existence of the second absorption band of chlorophyll and, consequently, of the second absorption band of photosynthesis. He studied the relation between photosynthesis and the intensity of illumination (1889) and gave the present generally known graphic expression of the light saturation of photosynthesis, approximately at half of full insolation. Timiryazev stated the basic results of his thirty-five-year research on photosynthesis in the Croonian lecture “The Cosmical Function of the Green Plant,” read to the Royal Society of London in 1903. From 1874 to 1903 he prepared a number of works for publication in the collection Sun, Life, and Chlorophyll (1923). The theoretical basis he provided for the energetics of photosynthesis is still valid, even though the quantum theory of light has replaced the wave theory.

Timiryazev’s success in his research in photosynthesis is explained to a large degree by the fact that he gave much attention to the working out of new methods and the study of physiological processes in plants, for which he himself constructed a number of instruments and devices. He formulated theoretical ideas on the watering and mineral feeding of plants. Timiryazev also felt that it was necessary to apply Darwinian principles, especially natural selection, to explain physiological processes in plants. He himself undertook an experiment to give such an explanation in relation to photosynthesis and the green color of chlorophyll. The fight to introduce the achievements of plant physiology into agriculture took up a large part of Timiryazev’s time.

Timiryazev was instrumental in the defense and development of Darwinism, especially in Russia. When he was only a student, he became acquainted with The Origin of Species and was able to see in its evolutionary theory the basis of a general theory of the organic world and to understand its materialistic basis. His books “A Short Sketch of the Theory of Darwin” (1865) and “Charles Darwin and His Theory” went through fifteen editions from 1883 to 1941. The ideas of Darwin occupied a central place in the posthumous “Historical Method in Biology” (1922).

BIBLIOGRAPHY

1. Orriginal Works. Timiryazev’s writings were published as Sochinenia, 10 vols. (Moscow, 1937–1940); see I, 475–495 for a bibliography of his works on plant physiology, Darwinism, and general questions of natural science. His selected works appeared as lzhrttnnyr sochinenia, 4 vols. (Moscow, 1948–1949).

His works include “Über die relative Bedeutung von Lichtstrahlen verschiedener Brachbarkeit bei der Kohlensäurezersetzung in Pflanzen,” in Botanische Zeitung, 27 (1869), 169–175; Spektralny analiz khlorofilla (“The Spectral Analysis of Chlorophyll” St. Petersburg, 1871); “Sur l’action de la lumiére dans la décomposition de l’acide carbonique par la granule de chlorophylle,” in Atti del Congresso botanico internazionale (Florence, 1876), 108–114; “Sur le rapport entre l’intensité des radiations solaires et la décomposition de l’acide carbonique par les végétaux,” in Comptes rendus. . . de l’Académie des sciences, 109 (1889), 379–382;and “The Cosmical Function of the Green Plant,” in Proceedings of the Royal Society, 72 (1903), 424–461, his Croonian lecture.

II. Secondary Literature. On Timiryazev and his work, see (listed chronologically) V. L Komarov, N. A. Maksimov, and B. G. Kuznetsov, Kliment Arkadievich Timiryazev (Moscow, 1945), with bibliography of secondary literature, 198–211; G. V. Platonov, Mirovozzrenie K. A. Timiryazeva (“Timiryazev’s World View” Moscow, 1952), 468–478; A. I. Korchagin, Kliment Arkadievich Timiryazev. Zhizn in Ivorchestvo (“. . . Life nd Activity”), 3rd ed. (Moscow, 1957); and E. M. Senchenkova, K. A. Timirayzev i uchenie of fotosinteze (“. . . and the Theory of Photosynthesis” Moscow, 1961).

E. M. Senchenkova