Nikolay W. Timofeeff-Ressovsky* (1900-1981)
An Essay on His Life and Scientific Achievements**

V. I. Ivanov and N. A. Liapunova

1. Introduction
2. Autobiographical Notes
3. Scientific Achievements
4. References

1 Introduction

Nikolay Wladimirowitsch Timofeeff-Ressovsky was an active member of the German Academy of Naturalists "Leopoldina" in Halle, an honorary member of the American Academy of Sciences and Arts in Boston, the Italian Society of Experimental Biology, the Mendel Society in Lund (Sweden), the British Society in Leeds, a founder member of N. I. Vavilov All-Union Society of Geneticists and Breeders (USSR), a member of the Max Planck Society for Promotion of Science (Germany), an honorary member of the Moscow Society of Naturalists, the USSR Geographical Society, and the All-Union Botanical Society (USSR), winner of medals and prizes of Lazzaro Spallancani (Italy), Darwin (Germany), Mendel (Czechoslovakia. Germany), and Kimber (USA). N. W. Timofeeff-Ressovsky (nicknamed Timo) achieved so much during the long years of his far from simple life that there would be enough material for a dozen scientific biographies. He paved new ways in science (patterns of gene expression in development, radiation genetics, biophysics, population genetics, and micro-evolution) and was a recognized scientist all over the world.

2 Autobiographical Notes

In his Autobiographical Notes Timo outlined very briefly the main periods of his life and work. The brevity of these notes allows us to quote them here in full:
  I was born in Moscow on September 7, 1900. My father. Vladimir Viktorovich Timofeerf-Ressovsky (1850-1913), was a railroad engineer. My mother was Nadezhda Nikolaevna T.-R. (maiden name Vsevolozhskaya, 1868-1928).
  I went to school first to the 1st Kiev Emperor Alexander Gymnasium (1911-1913) and then to Moscow Flerov Gymnasium (1914-1917), Shanyavskii Moscow Free University (1916-1917) and the 1st Moscow Stale University (1917-1925).
  I worked as biology teacher at the Prechisienka District primary school in Moscow (1920-1925), zoology teacher at the Biotcclimcul Faculty. Moscow Practical Institute (1922-1925), assistant at the Department of Zoology (Prof. N. K. Kol'tsoff), Moscow Medical Pedoiogical Institute (1924- 1925). and as a research assistant at the Institute of Experimental Biology, State Institute of Health (Director Prof. N. K. Kol'tsoff).
  Invited by the Kaiser Wilhelm Gesellschaft fur die Fordcrung der Wissen-schaftcn in Berlin and recommended by Prof. N. K. Kol'tsofIT and USSR People's Commissar (Minister) of Health N. A. Scmashko. I worked as a research worker (1925-1946) and as the director (1945) of the Department of Genetics at the Institute of Brain Research in Berlin-Buch.
  Since 1947 I worked as the head of the Biophysicai Department of an anonymous institute P.O.B.No. 0211 (1947-1955); of the Department of Radio-biology and Biophysics, Institute of Biology, Ural Branch of the USSR Academy of Sciences, Sverdlovsk (1955-1964); Department of Radiobiology and Genetics, Institute of Medical Radiology, USSR Academy of Medical Sciences, Obninsk, Kaluga District (1964-1969), and as a consultant at the Institute of Medical-Biological Problems, Moscow, since 1969.
  Having been trained as a zoologist and retaining my interest in zoology from youth (specifically, zooplankton, freshwater fish, aquatic and coastal birds of the Paleoarctics), I was engaged in the study of the hydrobiology of mid-Russian lakes in 1920-1923 and, mainly, genetics, biophysics, and problems of evolution from 1920 until now. In the field of genetics I was engaged from the 1920s, using mainly Drosophila as an object in phenogenetics, mutation processes, population genetics, and the development of some foundations of the micro-evolutionary processes.
  From the 1930s and up to the beginning of the 1960s I studied the accumulation and release of some chemical elements by. predominantly, hydro-bionts and land plants, using the method of labeled atoms (radioisotopes). This work was centered on the fate of some elements of biogcocoenoses.
  Over 18 years (from the end ofthf 1920s up to the mid-1960s), I carried out, together with a small group of collaborators, systematic-zoogeographical and experimental-genetic work with the aim of making a comprehensive estimation of intraspecific variation in a herbivorous ladybird, Epilacha chrysomelina F. This  study was related to the analysis of microevolutionary processes.
  As to more general achievements in some fields of modern science. 1 took an active part in the development of hit, target, and enhancer principles in radiobioiogy, in the development and classification of variation in phcnotypic manifestations, mostly at the late postembryonic stages, of the features determined by certain mutations under the effect of genotypicul, external, and "internal" medium in the field of phenogenetics, phenomenology of gene expression, and. finally, in the formulation of elementary materials and factors of the microevolutionary process and the relationship between micro- and macroevoiution.
  Theoretical analysis and organization of the data obtained us a result of experiments and observations were greatly promoted due to two factors-First, in the early 1920s, the group headed by S. S. TschetvenkotT at the Institute directed by N. K. Kol'tsoff organized a group for joint discussion of all studies and the most important literature on problems of interest. Soon, when Drosophila became the main experimental object, this group was called "Drozsoor" (from Russian), which means "joint shouting of drosophilists".
  Later, throughout my entire life, together with my collaborators and closest friends from other laboratories, I was always organizing similar, absolutely informal, and free discussions which stimulated scientific life and helped in research. Second, the-general development of my interests and the achievement of necessary strictness in formulation of the most essential biological concepts by myself and some of my colleagues were greatly influenced by a happy combination of conditions. This made it possible for me to get acquainted, in some cases become friends and, sometimes, become involved in scientific cooperation with many eminent mathematicians, physicists, chemists, geologists, geographers, and biologists, not only in this country, but also abroad-Specifically, 1 was lucky enough to participate in some seminars of the "Niels Bohr Circle" in Copenhagen and to organize, together with B. S. Ephrussi (with the financial aid of the Rockefeller Foundation), a small (about 20 members) international group of physicists, chemists, cytologists, geneticists, biologists, and mathematicians who were interested in discussing the problems of theoretical biology (this group met at the end of the 1930s, before World War II, at nice resorts in Denmark, the Netherlands, and Belgium) ..." (end of quotation, manuscript dated 1977).

3 Scientific Achievements

The beginning of the scientific activity of Timo coincided with the hard times encountered during military intervention and civil war in Russia. The relatively quiet course of academic life was repeatedly interrupted by military service or forced teaching at primary school in order to earn money. However, nothing could reduce the persistence and enthusiasm of the young From the very first steps in science until (he end of his life. science remained the m:iin locus ol Timofeeff-Ressovsky. Already in 1923, having not yet completed his university (mining, he became an educated zoologist whose opinion u'as held in high esteem by his venerable teachers. N. K. Kol'tsoff and S. S. Tscheiverikoff.
  Being a zoolugist by vocation and education, Timofeeff-Ressovskv continued the genetic and evolutionary work started by his teachers.
  The first genetic work of Timo, which started a large series of studies on the "phenomenology of gene expression" [W. Haecker(l918, 1925) termed this area "phenogenetics" and it now constitutes part of developmental genetics], was the study of the phenotypical expression of a mutation ("genovariation" according to terminology introduced and used by S. S. Tschetverikoff and his students) radius incompletus in Drosophila funebris. This study was started in summer 1923 and consisted of the genetic analysis of a newly found hereditary change in wing venation. However, already in the first publication on the phenotypic expression of this feature Timo introduced three fundamental principles of phenogenetics (Timofeeff-Ressovsky 1925a). Two of them referred to the quantitation of the realization of genetic anlagen in the features of an organism. These were phenotypical manifestation and expression of the gene. Timo defined phenotypical manifestation as "the very fact of gene manifestation in the phenotype" and phenotypical expression as "the form and degree of expression the feature assumes in individual organisms". In the paper published together with 0. Vogt in German, these notions were termed "Penetranz" and "Expressivitat" (Timofeeff-Ressovsky and Vogt 1926), and were accepted in all European languages and recognized in genetic literature.
  Experimental studies of penetrance and expressivity of radius incompletus in different strains of D. Funebris and their hybrids led Timo to the conclusion of genetic stipulation of these phenogenetic parameters. He also formulated a third fundamental principle of genetics, namely, that "a feature, even simply Mendelian, can be influenced by many genes and, vice versa, an individual gene can exert multiple effects. This creates a concept of systemic action of the genotype and the influence of hereditary constitution on penetrance and expressivity of an individual gene" (Timofeeff-Ressovsky 1925a).
  The first studies on penetrance and expressivity of radius incompletus and vti (venae transversae incompletae) were followed by a cascade of intensive research in the field. These included investigations of heterogeneous groups of genes which control the same features (Timofeeff-Ressovsky and Vogt 1926), specificity of gene expression (Timofeeff-Ressovsky 1929a), effects of temperature on gene expression (Timofeeff-Ressovsky 1928), dependence of viability of certain mutations and their combinations in D. funebris on genotypical and external factors (Timofeeff-Ressovsky 1934b), and other novel investigations in the field of experimental phepogenetics. Already in his first studies, Just as in many later ones. Elena Aleksandrovna Timofeeva-Resovskaya (Helen A. Timofeeff-Ressovsky), his lifetime companion, was his faithful collaborator and co-author.
  Two "compilations" (as Timo designated the "genre" of the papers) on phenomenology of gene manifestation (Timofeeff-Ressovsky 1934d, 1940c) were of exceptional importance. The latter was a summary of the author's and other published data on the variation of expression of genes and their combinations, heterogeneous groups and pleiotropy, types of symmetry, interallelic relationships, etc. The essence of this work is represented as a schematic diagram (Fig. 1). According to this scheme, the pathway from a gene a to the final (definitive) feature A, which it controls, is mediated, as a rule, through one (or more) intermediate stages alpha. Various steps of this complicated pathway can be affected by some other genes of the same (b, c) and of other chromosomes (d-n), as well as by factors of the intraorganisrnic (x) and external (o, p, q) environment. As a result, the phenotypical feature is formed as a product of coordinated interaction of the controlling gene with a complex of factors of the genotypic, internal, and external milieu. Variation in all components of this complex process determines the ambiguity of the relationship between the gene and the feature it controls and the variation in the expression of the feature within a certain reaction norm. This is shown in the diagram by the markedly larger size of the rectangle A, as compared to the circle a.
  Extending the principle of systemic regulation from individual phenotypical features to the genetic control of development, as a whole, provides a key for constructing a general theory of ontogenesis to explain why in the development of multicellular organisms due events occur in due time and at due locations (Timofeeff-Ressovsky and Ivanov 1966: Timofeeff-Ressovsky et al. 1977)
  The foundations of the concepts of developmental genetics, laid down by Timo more than 60 years ago and put in its final form almost 50 years ago, retain their heuristic value even today. Since that time. with reaped to advances in experimental embryology, developmental physiology, and molecular biology, these general concepts, as applied to developmental processes such as segmentation in insects, hemopoiesis and immunopoiesis. were made more concrete in terms of corresponding structural and functional changes at the molecular, cytological, histological, and organismic levels.
  In parallel with phenogenetic studies, Timo carried out in the 1920-1930s a large series of investigations into population genetics and evolution. These investigations were initiated by S. S. Tschetverikoff who set [he task of examining the genotypic composition of natural populations of animals. Many of Tschetverikoff's students took part in this project, including the Timofeeff-Ressovskies. In 1927 their first mutual population-genetic study was published (Timofeeff-Ressovsky and Timofeeff-Ressovsky 1927) in which a natural population of D. melanogaster from an area in southern Berlin was analyzed. As a result of inbreeding of the collected flies, it was established that natural populations, just as laboratory cultures, contain abundant recessive mutations in a heterozygous state. This conclusion regarding the abundance of recessive mutations in populations, based on the experimental analysis, fully confirmed the theoretical prediction by S. S. Tschetverikoff( 1926) in his classical work "On some moments of the evolutionary process from the standpoint of modern genetics". This work, together with the results by J. B. S. Haldane. R. A. Fisher, and S. Wright, gave rise to modern population genetics. The general biological importance of this conclusion was enhanced by the fact that similar data were obtained by other researchers who studied the genotypical composition of natural populations of diverse organisms. According to Timo's formulation, "Populations of a species are filled up with mutations, just as a sponge with water."
  In his later studies on population genetics, Timo investigated problems of geographical variation in populations (Timofeeff-Ressovsky l932a, 1935a), viability of various genotypes (Timofeeff-Ressovsky l934b-d). radiation genetics of populations (Timofeeff-Ressovsky 1934c) and genetic polymorphisms (Timofeeff-Ressovsky 1940b). Special merit in the history of population and evolutionary genetics is to be given to a series of three communications in which the Timofeeff-Ressovskies reported on changes in the abundance and taxonomic composition of different Drosophila colonies (Timofeeff-Ressovsky and Timofeeff-Ressovsky 1940).
  Here, it is appropriate to discuss some problems related to Timo's paper "Experimental study of the hereditary load of populations" published in 1935 in a supplement to the Journal of the Society of Physicians Erbarzt (Timofeeff-Ressovsky 1935a). This work is a popular presentation of the principles of population genetics for physicians, in which an extrapolation into the field of human genetics had been made. Based on the data on animal and plant genetics, Timo drew conclusions on the importance of biological phenomena for understanding the problems of hereditary health in man. Using the terminology in German genetic literature of the time, Timo designated these problems (hereditary health of man. i.e., medical genetics) as problems of "racial hygiene". It should be noted that in prewar, German scientific literature the term "racial hygiene" included areas which were directly opposed to each other, such as the early steps of humanitarian postwar medical genetics and chauvinist racial "theory", which actually abused science.
  The concepts regarding the role of decreased selection pressure on the increase in genetic load in human populations, the role of dominant mutations and mutations influencing viability, the geographical distribution of genes. variations in genes, etc., extrapolated by Timo from animal and plant populations. anticipated the laws of human genetics, which were substantiated by direct observations only after World War II.
  With regard to Nazi racists using Timo's studies to "justify" their inhuman social politics, this accusation is as groundless as blaming Newton for airplanes crashing due to gravitation.
  The culmination of Timo's studies in population genetics was a cascade of publications in 1939-1941 (Timofeeff-Ressovsky 1939a,b, 1940a. 1941) in which the fundamental concepts of the genetic foundations of the evolutionary process (theory of microevolution) were outlined ever more distinctly from communication to communication. These concepts were largely the same as the ones developed by Th. Dobzhansky. The essence of this theory was later presented bv Timo in his classical paper Microevolution published in Russia (Timoleeff'-Ressovsky 1958). In earlier papers he consistently developed the concept that populations comprise elementary objects of the process of microevolution and a stable change in their genotypical composition is an elementary evolutionary event. The latter is based on mutations whose appearance and fate in a population are determined by the combined effect of such factors as the mutation process, drastic fluctuations in the size of populations ("waves of life" according to S. S. Tschetverikoff), isolation, migration, and selection.
  This analysis of the microevolutionary process is interesting in one more respect: it distinctly showed the methodology of scientific reasoning characteristic of its author. In a phenomenon of Nature to be interpreted, Timo distinguished its elementary material basis, the main factors whose influence on the elementary material constitutes the mechanism of the phenomenon, the main conditions determining the course of the process, and, finally, elementary events which are the result of the effect of all the factors on the elementary material under particular natural-historical conditions. Timo used to say that this methodological approach appeared as a result of his participation in Niels Bohr's Copenhagen colloquia. This seems to be true but it should be added that general theoretical views of physicists found in him a very diligent student.
  Later, Timo returned once more to the problems of evolutionary theory and population biology and gave a comprehensive followup in two books written together with N. N. Vorontsov and A. V. Yablokov (Timofeeff-Ressovsky et al. 1969) and with A. V. Yablokov and N. V. Glotov (Timofeeff-Ressovsky et ai. 1973).
  An everlasting interest in the mutation process can be followed during the entire scientific career of Timo. Already in 1925 he published his observation made in autumn 1924 on the appearance of a heterozygous normal male in a homozygous culture of radius incompletus (ri) in D. funebris (Timofeeff-Ressovsky 1925b). Having analyzed the progeny of  the crosses of this male with ri and ri + females, Timo came to the conclusion that this male originated as a result of reverse genovariation (mutation, in current terms) to gene ri. Later. Timo broadened this problem and studied not only the appearance of direct and reverse mutations, but also of mutations of certain luci in several different directions, especially in a series of multiple alleles of the white locus in D. melanogaster (Timofeeff-Ressovsky 1929b). Already at the earliest stages of this research Timo started to apply X-irradiation to flies in order to accelerate the mutation rate. similarly to the just recently discovered radiation mutagenesis (Muller 1927). The data concerning relative frequencies of forward and back mutations of the white locus in D. melanogaster are described most fully in the Proceedings of the VI International Congress of Genetics in 1932 (Timofeeff-Ressovsky 1932b).
  Timo himself believed at that time that the main importance of his observations consisted in the experimental confirmation of the reversibility of point mutations. However, modern data suggest that among the point mutations induced by X-rays, only some are reversible, since most of them are micro-deletions. Another aspect of these studies appears to be more important today: they represented the first systematic study of quantitative and qualitative patterns of radiation mutagenesis and this allowed one already in the 1930s to propose the first theories on the nature of the mutation process and the structure of the gene.
  It was successively established that:
- mutations can arise both in germ cells and in somatic cells (Timofeeff-Ressovsky 1929c);
- there is no aftereffect of irradiation in radiation mutagenesis (Timofeeff-Ressovsky 1930a);
- the yield of gametic mutations is higher following irradiation of mature sperm of Drosophila than after irradiation of earlier stages of spermatogenesis (Timofeeff-Ressovsky 1930b);
- the mutability of "normal" alleles of the same loci from geographically distant populations can be different (Timofeeff-Ressovsky 1932a);
- the yield of mutations induced by X-rays is linearly related to radiation dose and is dependent on the type of radiation, dose rate, and temperature (Timofeeff-Ressovsky 1934a);
- all types of ionizing radiations and of fast particles tested reaching the chromosomes of the cells whose progeny is studied for induced mutations are genetically effective (Wilhelmy et al. 1936; Zimmcr and Timofeeff-Ressovsky 1936; Timofeeff-Ressovsky 1937a, b; Timofeeff-Ressovsky and Zimmer 1938 and other publications);
- unlike the linear dose-effect relationship for point mutations, the dose-effect relationship for chromosome mutations is nearly quadratic (Timofeeff-Ressovsky 1939c).

  Taken together, these and related data in radiation genetics made up the sic phenomenology for a theory on the genetic effect of radiation (Timofeeff-Ressovsky 1934f). Most of these data are still valid today, although some of ;m, e.g., concerning the lesser effectiveness of fast neutrons as compared to rd X-rays, were revised by various authors.
  For many years of comprehensive studies in radiation genetics, the main members of the Berlin-Buch team formed by Timo included E. A. Timofeeva-Ressovskaya. K. G. Zimmer, M. Delbriick, H. J. Born, A. Katsch. and others. iis team played the key role in the progress in understanding the nature of mutations in the 1930-1940s.
The paper by N. W. Timofeeff-Ressovsky, K. G. Zimmer, and M. Delbruck published in "Nachrichten von der Gesellschaft der Wissenschaften zu Gottingen" under the title "Uber die Natur der Genmutation und der Genstruktur" (Timofeeff-Ressovsky et al. 1935) was of primary importance for the development of both radiation and molecular genetics. This paper, known among scientists as the "Grunes Pamphlet" (due to the color of the cover), is an example of  the productive cooperation of three scientists who complemented each other.K. G. Zimmer, assumed to be the most accurate person at that time (according  to the testimony of Timo), performed radiation dosimetry in radiation-genetic experiments. M. Delbruck developed elegant mathematical solutions of problems concerning the size of effective volumes to be hit in order to induce a single munation event. Timo was not only the leader of the whole project, performing all the crosses and looking for mutations himself, but he also contributed to this work the ideas of his teacher N. K. Kol'tsoff concerning "hereditary molecules"(Kol'tsoff 1928). Apparently, Timo's participation in Copenhagen's "Bohr Circle" was also important. Taken together, all these circumstances led not only to the formulation of the foundations of modern radiation genetics, but also to the determination (in the "premolecular" era) of the probable size of an individual gene: approximately 300 atomic radii for the spherical model, which corresponded to the macromolecular size of genes. One can judge the role of this work in the development of molecular genetics from the fact that after half a century one of the leading authorities in this field, the Nobel prize winner M.Perutz (1987), said that the everlasting importance of the well-known book by E. Schrodinger "What is Life?" (1944) consisted in popularization of the contents of the "Grunes Pamphlet".
  Development of radiation-genetic, radiobiological, and biophysical lines of research continued in Timo's subsequent studies and new data and generalizations were given in every new "compilation" (Timofeeff-Ressovsky 1937b, 1940d: Timofeeff-Ressovsky and Zimmer 1939). In 1947 the book by N. W. Timofeeff-Ressovsky and K. G. Zimmer Biophysik. Vol. 1, Das Treffer-Prinzip in der Biologie was published in Leipzig (Timofeeff-Ressovsky and Zimmer 1947). At that time, the authors carried out their studies far from Leipzig in the southern Urals.
  Later, during the Obninsk period of his life (1964-1981), Timo and his collaborators published one more "compilation" (Timofeeff-Ressovsky et al.1966) and two books summing up the biophysical line of research: Application of Hit Principle to Radiobiology (Timofeeff-Ressovsky et al. 1968) and Introduction to Molecular Radiobiology (Timofeeff-Ressovsky et al 1981).
  Timo's radiobiological research was not limited to the study of biological effects of irradiation on organisms. Already, since his early studies in the field (Born et .al. 1941. 1942), he was concerned with the problems of the turnover of radioactive substances in organisms. These publications were among the earliest studies employing the method of labeled isotopes in biology. Further progress regarding physiological and, especially, ecological aspects led to the publication of numerous studies on the fate of microelements in the biosphere. During the last 30-35 years of Timo's scientific activity, this was one of his main topics of research. From the very beginning Timo approached these problems on the basis of biogeochemical and biogeocoenological concepts. It suffices to cite here only a few (out of many) of his publications in this field (1957-1962) to point out what important problems were raised and developed by him: "Application of radiation and radioactive substances in experimental biogeocoenology" (Timofeeff-Ressovsky 1957), "Effects of radioactive substances on the biomass and structure of terrestrial, soil and freshwater biocoenoses" (Timofeeff-Ressovsky et al. 1957), "On desactivation of water by soils and aquatic coenoses" (H. A. Timofeeff-Ressovsky et al. 1960), "On radioactive pollution of the biosphere and the measures of the pollution control", "Some problems in radiation biogeocoenology" (Timofeeff-Ressovsky 1962 a, b). The latter paper is a review and an analysis of a large series of studies on the processes of distribution, concentration, and scattering of radioactive substances in natural and model biogeocoenoses. In this work, the experimental data were considered within the framework of an original version of the concept of multilevel organization and functioning of live systems, rather than a formal descriptive treatment of the topic. General theoretical concepts of  Timo are given also in a small but extremely interesting publication "On some principles of classification of biohorological units" (Timofeeff-Ressovsky 1961).
  These studies demonstrated the deep devotion of  Timo to the traditions of Russian naturalists developed by V. V. Dokuchaev, V. I. Vernadsky, V. N. Sukatschev - traditions of comprehensive studies (on the basis of quantification) of natural phenomena as a unity and of their interrelations and interdependences (in a systemic manner, according to the current terminology). In his biogeocoenological studies Timo investigated the natural phenomena not only as a biologist, soil scientist, or geochemist, but, first of all, as a naturalist. And it is quite understandable that he gave special credit to V. I Vernadsky as one of the great naturalists of this century.
  During the last period of his research activities, Timo paid special attention to the global problem which he designated "Biosphere and Mankind" (see, for example, the publication under this title; Timofeeff-Ressovsky 1968). While reading now his discourses on this topic published more than 20 years ago, one is fascinated by the insight with which he posed tasks in the field of protection and rational utilization of natural resources (the tasks of real development of biosphere into noosphere, after Vernadsky 1944). These problems are now fully recognized but are as yet poorly solved.
  Timo was both an inquisitive and indefatigable naturalist and inspired teacher or, rather, a preacher for whom the transmission of knowledge to any audience was a life demand rather than duty. When Timo moved to Berlin and settled there for 20 years, he began to form a team of his associates and followers. Besides his faithful lifetime companion. Elena Aleksandrovna. a number of zoologists and botanists, physicists and physicians, chemists and geneticists, and many others worked with him. All of them were sure that Timo was the spirit of he party rather than simply the leader.
  As a brilliant and erudite man of indefatigable energy and as ardent polemist, Timo, wherever he lived, in Moscow, Berlin, Sverdlovsk, or Obninsk, regularly organized lectures, seminars, and home "tea parties", where not only current research was discussed, but also the general problems of science, art, and history: "from astronomy to gastronomy", according to him.
  The present essay has only outlined, rather than considered in any detail, the results of  N. W. Timofeeff-Ressovsky's research in different fields of genetics and biology. Even such a brief essay can show what a broad-minded scientist, a true naturalist in the best traditions of science, Timo was. His rich scientific heritage, represented by many, sometimes, hardly accessible publications, contains many ideas and facts which have not only retained their importance, but have acquired new depth and significance with time.

Acknowledgement. The authors are grateful to Dr. S. G. Vasetlsky for his invaluable discussions and help with the preparation of the English version of the manuscript.


Born HJ, Timofeeff-Ressovsky NW, Zimmer KG (1941)
  Anwendungen der Neutronen und der kunstlichen
  radioaktiven Stoffe in Chemie und Biologic.Umschau 6:2-6
Born HJ, Timofeeff-Ressovsky NW, Zimmer KG (1942)
  Biologische Anwendungen des Zahlrohres.
  Naturwissenschaften 30:600-603
Haecker W (1918) Entwicklungsgeschichtliche
  Eigenschaftsanalyse (Phanogenetik).Fisher,Jena
Haecker W (1925) Aufgaben und Ergebnisse der
  Phanogenetik. Bibliographia Genedka, 1, 93
Kol'tzoff NK (1928) Physico-chemical bases of morphology.
  In: Proc 3rd Russian Congr of Zoology, anatomy and
  histology. Leningrad, pp 39-41 (in Russian)
Muller HJ (1927) Artificial transmutation of the gene. Science
Perutz MF (1987) Physics and the riddle of life. Nature
  326:555-558 Schrodinger E (1944) What is life? The
  physical aspect of the living cell. Cambridge University
  Press, Cambridge
Timofeeff-Ressovsky HA, Timofeeff-Ressovsky NW (1927)
  Genctische Analyse einer freilebenden Drosophila
  melanogaster Population. Wilhelm Roux" Arch
  Entwicklungsmech Org 109:70-109
Timofeeff-Ressovsky HA, Agafonov BM, Timofeeff-Ressovsky NW (1960)
 On desactivation of water
  by soils and aquatic coenoses. In: Proc Inst Biol Ural
  USSR Acad Sci 13:35-48 (in Russian)
Timofeeff-Ressovsky NW (1925a) On phenotypic
  manifestation of a genovariation in Drosophila funebris. In:
  Proc 2nd Russ Congr Zool. Moscow, pp 159-161 (in
Timofeeff-Ressovsky NW (1925b) Back genovanriation in
  Drosophila funebris. J Exp. Biol.Ser.A 1:143-144 (in
Timofeeff-Ressovskv NW(1928) Effect of temperatureon the
  formation of transverse veins in wings of a genovariation in
  Drosophila funebris. J Exp Biol Ser A 4:199-214 (in
Timofeeff-Ressovsky NW (1929a) The phenotypic
  realization  of the gene vti in Drosophila funebris In:Proc
  Russ Congr on Genetics selection, seed production and
  animal breeding, vol 2. Leningrad, pp 483-488 (in Russian)
Timofeeff-Ressovskv NW(1929b) Ruckgenovariationen und
  die Genovariabilitat in verschiedenen Richtungen. Wil'helm
  Roux Arch Entwicklungsmech Org 115:620-635
Timofeeff-Ressovsky NW (l929c) The effect of X-rays in
  producing somatic genovariations of a definite locus, in
  different directions in Drosophila melanogaster Am Nat
Timofeeff-Ressovsky NW (l930a) Is there an "aftereffect" of
  Rontgenization on the process of genovariation? J Exp Biol
  Ser A 6:79 -83 (in Russian)
Timofeeff-Ressovskv NW (1930b) On the problem of gene
  action in germ cells. J Exp Biol Ser A,6:181-l87(in Russian)
Timofeeff-Ressovsky NW (1932a) Verschiedenheit der
  normalen Allele der white-Serie aus zweigeographisch
  gelrennten Populationen von Drosophila melanogaster.
 Biol Zentralbl 52:468-476
Timofeeff-Ressovsky NW (1932b) Mutations of the gene in
  different directions. In: Proc 6th lnt Congr Genet, vol 1. pp
Timofeeff-Ressovsky NW (l934a) Einige Versuchc
  Drosophila melanogaster iiber die Beziehungen zwischen
  Dosis und Art der Rontgenbestrahlung und der dadurch
  ausgelosten Mutationsrate. Strahlentherapie 49:463-478
Timofeeff-Ressovsky NW (1934b) Uber den Eintflus-des
  genotypischen Milieus und der Aubenbedingungen auf die
  Realisation des Genotyps Genmutation vti bei Drosophila
  funebris.Nachr Ges Wiss Gottingen. Biol 1:53-106
Timofeeff-Ressovsky NW (1934c) Uber die Vitalitat einiger
  Commutationen und ihrer Kombinationen bei Drosophila
  funebris und ihre Abhangigkeit vom genotypischen und
  vom  auberen Milieu. Z Indukt Abstammungs Vererbungsl
Timofeeff-Ressovsky NW (1934d) Verknupfung von Gen
  und Aubenmerkmal (Phanomenologie der
  Genmanifestierung). Wiss Woche Frankfurt 1 92 115
Timofeeff-Ressovsky NW (1934e) Auslosung von
  Vitalitatsmutationen durch Rontgenbestrahlung bei
  Drosophila melanogaster. Strahlentherapie 51:658-663
Timofeeff-Ressovsky NW (1934f) The experimental
  production of mutation,. Biol Rev 9:411-457
Timofeeff-Ressovsky NW (1935a) Uber geographische
  Tempera turrassen bei Drosophila funebris. Arch
  Naturgesch 4:.245-257
Timofeeff-Ressovsky NW (1935b) Experimentelle
  Untersuchungen der erblichen Belastung von Populationen.
  Erbarzt 2, (8):117-118.
Timofeeff-Ressovsky NW (1937a) Zur Frage uber einen
  "direkten" oder "mdirekten" Einflub der Bestrahlung auf den
   Mutationsvorgang. Biol Zentralbl 57:233 248
Timofeeff-Ressovsky NW (1937b) Experimenlelle
  Mutationsforschung in der Vererbungslehre. Theodor
  Steinkopf, Dresden
Timofeeff-Ressovsky NW (1939a) Genetik und Evolution Z
  Indukt Abstammungs Vererbungs 76:158-218
Timofeeff-Ressovsky NW (1939b) Genetica ed evoluzione.
  Sci Genet 1:278-281
Timofeeff-Ressovsky NW (1939c) Zur Frage der
  Beziehungen swischen strahlenausgelosten Punkt und
  Chromosomenmutationen bei Drosophila. Chromosoma
  (Berl) 1:310-316
Timofeeff-Ressovsky NW (1940a) Mutations and
  geographical variation. In: Huxley J (ed) The new
  systematics. Cambridge, pp 73-136
Timofeeff-Ressovsky NW (1940b) Zur Analyse des
  Polymorphismus bei Adalia hipunctata L. Biol ZenlralbI
Timofeeff-Ressovsky NW(1940c) Allgemeine Erscheinungen
  der Gen-Manifestierung. In Just G(ed) Handbuch der
  Erbbiologie des Menschen. Bd 1. Springer. Berlin, pp
Timofeeff-Ressovsky NW(1940d) Allgemeines uiber die
  Entstehung neuer Erbanlagen. In Just G (ed) Handbuch der
  Erbbiologie des Menschen. Bd 1. Springer. Berlin, pp
Timofeeff-Ressovsky NW(l941) Mutationen als Material der
  Rassen  und Artbildung. Gesundheitsfuhrung 3:90-97
Timofeeff-Ressovsky NW (1957) Application of radiation
  and radioactive substances in experimental
  biogeocoenology. Bot J 42:161-194 (in Russian)
Timofeeff-Ressovsky NW (1958) Microevolution. Primary
  events, material and factors of the process of
  microevolution.   Bot J 43:317-336 (in Russian)
Timofeeff-Ressovsky NW (1961) On some principles of
  classification of biohorological units. In: Proc Inst Biol Ural
  Branch USSR Acad Sci 17:23-28 (in Russian)
Timofeeff-Ressovsky NW (l962a) On radiactive pollution of
  the biosphere and measures of the pollution control. In:
  Proc  Inst Biol Ural Branch USSR Acad Sci 22:7 16 (in
Timofeeff-Ressovsky NW (1962b) Some problems in
  radiation biogeocoenology Thesis, Univ Sverdlovsk
Timofeeff-Ressovsky NW (1968) Biosphere and the
  mankind. In: Sci Proc Obninsk Banch Geoaraph Soc
  USSR   1:3-12 (in Russian)
Timofeeff-Ressovsky NW. Ivanov VI (1966) Some
  problems  of phenogenetics. In: Actual problems in modern
  genetics. Moscow University Press, Moscow, pp 114-130
  (in Russian)
Timofeeff-Ressovsky NW. Timofeeff-Ressovsky HA (1940)
  Populationsgenetischc Versuche an Drosophila Teil 1-3. Z
  Indukt Abstammungs Vererbungs 79:28-49
Timofeeff-Ressovsky NW. Vogt 0 (1926) Uber
  idiosemantische Variationsgruppen und ihre Bedeutung fur
  die Klassifikation der Klassikheiten. Naturwissenschaften
Timofeeff-Ressovsky NW. Zimmer KG (1938) Auslosung
  von Mutationen an Drosophila malanogaster durch Li + D -
  Neulronen. Naturwissenschaften 26:108-109
Timofeeff-Ressovsky NW. Zimmer KG (1939)
  Strahlengenetik. Strahlentherapie 66:684-711
Timofeeff-Ressovsky NW, Zimmer KG (1947) Biophysik,
  Bd 1. Das Treffer-Prinzip in der Biologie Hirzel. Leipzig
Timofeeff-Ressovsky NW. Zimmer KG. Delbrueck M
  (1935) Uber die Natur der Genrnutation und der
  Genstruktur. Nachr Ges Wiss Gottingen, Biol 1:189-245
Timofeeff-Ressovsky NW, Poryadkova NA,Sokurova EN,
  Timofeeff-Ressovsky HA(1957) Effects of radioactive
  substances on the biomass and structure of terrestrial, soil
  and freshwater biocoenoses. In: Proc Inst Biol Ural Branch
  USSR Acad Sci 9:202-251 (in Russian)
Timofeeff-Ressovsky NW. Glotov NV. Ivanov VI (1966)
  Some problems in radiation genetics. In Actual problems in
  modern genetics. Moscow University Press, Moscow, pp
  412-433 (in Russian)
Timofeeff-Ressovsky NW. Ivanov VI. Korogodin VI (1968)
  Application of hit principle to radiation biology. Atomisdat.
  Moscow (in Russian) (German version: VEB Gustav
  Fischer. Jena 1972)
Timofeeff-Ressovsky NW. Vorontsov NN, Jablokov AV
  (1969) A brief review of the theory of evolution. Nauka,
  Moscow (in Russian) (German version: VEB Gustav
  Fischer. Jena 1975)
Timofeeff-Ressovsky NW. Jablokov AV, Glotov NV
  A review of the theory of populations. Nauka. Moscow (in
  Russian)(German version: VEB Gustav Fischer.Jena 1977)
Timofeeff-Ressovsky NW. Ginter EK. Ivanov VI (1977) On
  some problems and goals in phenogenetics. In: Problems in
  experimental biology, Nauka, Moscow, pp 186-195 (in
Timofeeff-Ressovsky NW. Savich AV. Shalnov MI (1981)
  Introduction to molecular radiobiologv Medicina. Moscow
  (in Russian)
Tschetverikoff SS (1926) On some moments of the
  evolutionary process from the standpoint of modern
  genetics. J Exp Biol Ser A 2:3-54 (in Russian)
Vernadsky VI (1944) A few words on noosphere. Adv Biol
  18:113-120 (in Russian)
Wilhelmy E, Timofeeff-Ressovsky NW. Zimmer KG (1936)
  Einige strahlengenetische Versuche mit sehr weichen
  Rontgenstrahlen an Drosophila melanogaster.
  Strahlentherapie 57:521-531
Zimmer KG. Timofeeff-Ressovsky NW (1936) Auslosung
  von Mutationen bei Drosophila melanogaster durch
  alpha-Teilchen nach Emanationseinatmung. Strahlentherapie

Research Centre for Medical Genetics, Russian Academy of Medical Sciences, Moskvorechie Str. I 115478 Moscow, Russia
* Spelling is according to that found in publications by N. W. Timofeeff-Ressovsky.
**In this essay some parts of the papers published in the Russian Journals Priroda 1990 No. 9 (V. I. Ivanov, "No prophet is accepted in his own country") and Biol Nauki (Sci. reports of high school) 1990 No. 4 (V. I. Ivanov, "Nikolay W. Timofeeff-Ressovsky: a scientist and teacher") are used with the kind permission of the respective editors.