Physiology

PHYSIOLOGY, one of the main branches of biology (see), whose tasks are: the study of the regularities of the functions of living organisms, the emergence and development of functions, and transitions from one type of functioning to another. Independent sections of this science are plant physiology and animal physiology. The latter is divided into general physiology, which studies the regularities of the properties of living organisms, and comparative physiology, which studies the regularities of the functions of animals in their similarity and difference. Having a direct relationship to practical questions of medicine and animal husbandry, physiology also organically includes in its problematic the development of questions of human physiology and physiology of agricultural animals. Until very recently, physiology to a large extent included facts and conclusions concerning only a small group of laboratory animals, and therefore the possibilities of actual use of these data in the interests of medical and animal husbandry practice were limited. Hence significant errors and misconceptions arising from the insufficiently critical transfer of data from laboratory animal physiology to agricultural animals and humans. An organic part of physiology at the modern level is biological chemistry (see), which studies physico-chemical processes, as well as to some extent pharmacology (see). The existing so-called physiological disciplines are branches of physiology that have grown on very different soils. Thus, for example, the most developed branches of physiology at the present time, such as biological chemistry, biological physics (see), physico-chemical biology, differ in their basis only in the methods of studying physiological phenomena (chemical, physical, physico-chemical); electrophysiology (see), which is still distinguished as a separate section, should also be included here. In addition to the isolation of special branches of physiology on the basis of the introduction of new research methods, this process also proceeded along the line of isolating individual sections of physiology into a separate discipline (see below). Special disciplines grew from completely different foundations, such as nutrition physiology and labor physiology, which arose at the end of the 19th and beginning of the 20th centuries as areas of physiology specially developed from the needs of labor rationalization and the tasks of agriculture. Comparative physiology is one of the least developed branches of physiology and biology in general. During its existence of more than a century, comparative physiology (including comparative biochemistry) has accumulated a huge amount of material that has great significance both theoretical and practical. Comparative studies of the functions of modern organisms, studies of the functions at various stages of individual development of the same animals, comparison and juxtaposition of these data, as well as the barely begun studies of the functions of extinct animals ('paleophysiology') provide the framework on which evolutionary physiology can be built as a science of the history of the development of complex physiological acts, a science whose study is necessary for the correct use of physiological data in the interests of practice. The role of comparative physiology is especially demonstrative in the field of animal husbandry sciences, where extensive research of physiological phenomena in agricultural animals makes it possible to confidently manage the processes in these animals, and in the field of medicine, where data from laboratory animal physiology were used to a large extent without critical transfer to humans. Knowledge of the history of the development of physiological processes allows one to make conclusions about the nature of one or another function, their origin, their correlations with other functions, etc., on a reliable scientific-biological basis. Main stages in the development of physiology. In the development of physiology, three periods can be outlined in basic terms: 1) the pre-Harvey period; 2) the period from Harvey to Lavoisier; 3) the period from Lavoisier to our time. This division of course cannot be understood strictly chronologically. The periods only characterize the main stages in the development of science, covering huge historical stretches of time. First period. This period, covering about 2,000 years (from the Greeks to Harvey), contains various historical stages in the development of physiology: a) the period of the founders of Greek philosophy and science, b) the period immediately before Harvey—the second half of the 15th century, 'from which modern natural science dates' (Engels). In the ancient world, when medicine in its theoretical views was completely under the influence of philosophical speculation (see Medicine) and almost did not use experiment, physiological concepts were abstract concepts derived from one or another philosophical system, and in part were 'genious guesses' of individual observers devoid of any instruments and methods of scientific research in our modern sense. This should include: Galen's refutation of the opinion about the absence of blood in the arteries; some guesses, such as the assumption of circular circulation of blood in Hippocrates, who has the following passage: 'From one vessel many arise; where its beginning and where its end, I do not know, for when a circle is formed, there is no possibility of finding the beginning.' In the field of digestion, Aristotle knew the action of the rennet; Galen described the passage of dissolved food into the intestine through the pylorus, as well as the movements of the stomach and intestines. In the field of respiratory physiology, Aristotle tried to establish a connection between the frequency of respiration in cold-blooded and warm-blooded animals; Galen performed a series of basic experiments that revealed the mechanism of lung movement, the role of the diaphragm, the internal and external intercostal muscles and nerves. Individual observations of ancient physicians about paralysis after damage to certain areas of the central nervous system also had enormous significance. Medieval scholasticism, with its slavish reverence for the authority of ancient science, contributed nothing to physiology, until the Renaissance era, when in physiology, as in other fields of knowledge, a revolution in scientific views occurred (see Medicine). The works of Servetus, author of the treatise 'Restitutio Christianismi', in which a refutation of the ancient teaching on the mechanism of blood circulation was given, as well as the works of a number of the greatest physicians, anatomists, and physiologists (Cesalpinus, Vesalius, Fabricius, etc.) had enormous significance for the further development of science, in particular as preparatory stages for the work of Harvey, with whose name the emergence of physiology as a science is associated. This also includes the work of the outstanding physician Van Helmont, who gave the first foundations for understanding the mechanism of respiration and the concept of the chemical nature of fermentative processes; his views formed the basis of the so-called iatrochemical school, which considers processes in the organism from a purely chemical point of view. At the end of the 16th century, the first foundations of the so-called iatromechanical school were laid. Second period (from Harvey to Lavoisier). The following moments are characteristic of this period: the decisive struggle against scholastic science of the Middle Ages as a reflection of the struggle against feudal foundations and a powerful impetus to the development of experimental natural science in general and experimental physiology in particular (see Medicine). Instead of abstract speculation, experience and observation are introduced into science, a quantitative approach to the study of physiological phenomena is introduced; the problematic characteristic of the era in the field of physiology is put forward, consisting in the comprehensive introduction of mechanics into the field of physiology. The theoretical work of Descartes raised the question of animal machines; Descartes tried to interpret a number of physiological phenomena on the basis of the laws of mechanics and physics. In his book on the movement of animals, Borelli gave the most vivid examples of the use of physical laws to explain physiological phenomena (physical foundations of percussion, a model of blood circulation based on the laws of hydraulics, etc.). Finally, brilliant, unsurpassed to this day in the breadth of coverage, experimental works by Harvey appeared. In the following more than 100 years, there were no similar major physiological studies, and mainly small painstaking work on collecting individual physiological facts prevailed as a reflection of the general state of metaphysical natural science of the 17th and 18th centuries. 'In the field of biology, they were mainly engaged in the accumulation and first selection of colossal material, both in botany and zoology, and in anatomy and proper physiology' (Engels). The appearance of the major works of materialist philosophers (Descartes, Le Roy, La Mettrie, Hobbes, Diderot, etc.) gave an impetus to the further development of physiology; the mechanistic approach to explaining biological phenomena, in particular physiological ones, began to strengthen; for this era, fascination with the construction of models of living organisms is characteristic; their authors nourished the hope 'to replace the frailty of the body with the endurance of steel and copper' (Helmholtz). The idealistic teaching of the arch by Van Helmont and the development of so-called vitalism (see) had a significant influence on physiology; vitalism tried to oppose its teaching about a 'super-mechanical force' characteristic only of organisms to the teaching about the possibility of explaining life phenomena by the laws of physics. Vitalists propagated their views in the criticism of purely physical approaches to explaining physiological phenomena and relied specifically on the complexity and unavailability of physical explanation of a number of discovered and described properties of living tissues, such as the phenomena of irritability. These views were especially intensively developed by the school of Montpellier. To this period belongs the substantiation of vitalism by the French Bordeu, Barthez, and others (see Vitalism).

By this time, through the work of Servetus, Vesalius, Malpighi, and others, clarity had been brought to the understanding of the previously confused process of blood circulation, culminating in the establishment of capillary circulation. The mechanism of respiration was already fairly well understood, and after the discovery of carbonic acid by Van Helmont, and the treatises and considerations expressed by Mayow on the identity of the respiratory process and combustion processes, conjectures were made about the chemistry of respiration, which was discovered at the end of the 18th century by Lavoisier. The foundation was laid for the doctrine of the function and structure of the digestive organs. Haller, by establishing the influence of bile on intestinal peristalsis, clarified the specific functions of the liver. The view of the digestive process as a chemical process was becoming firmly established. As early as Descartes, the significance of gastric juice had been established. Schwarz and Haller, on the basis of experiments and vivisection, sufficiently clearly outlined the character of the motor and secretory activity of the stomach. The formation of chyle and the anatomy of chyliferous vessels were studied in particular detail. In Lister's experiment, the absorption of substances from the intestine into the chyliferous vessels, and from there into the blood, was clearly demonstrated. The old views of the Galenic school on heat production in the heart, as well as Van Helmont's view of metabolism as a fermentative process, were placed on a chemical basis with the development of chemistry from the middle of the 18th century. Haller believed that heat production occurred through the nutrients entering the body with chyle, which the insightful Mayow linked to oxidative processes, combustion processes. Boerhaave, as a representative of the iatromechanical school, tended to explain heat production as the friction of blood against the walls of blood vessels. The nature of the nerve current was still unclear, although in 1743 the work of the Leipzig scientist Henssen was published, who made some assumption about the electrical nature of the nerve current, and somewhat later (1757-1765) the corresponding works of Aldani and Fontana appeared, direct predecessors of Galvani. Kratzenstein (in 1745) already used static electricity in the treatment of paralysis. Through the joint work of physicians, anatomists, and physiologists, basic knowledge about nerve fibers was established. The cranial pairs of nerve fibers were already largely described. Kaaten (1673) accurately described the anterior and posterior roots, and as is known, Descartes first introduced the concept of reflex. Cesalpinus showed the dependence between the nervous system and blood circulation, noting that the cessation of blood circulation deprives the corresponding area of sensitivity, and Van Helmont as early as the beginning of the 17th century pointed out that painful irritations are perceived by peripheral nerves. The brain and spinal cord were studied mainly by anatomists, while physicians provided valuable observations for Physiology. Haller noted disturbances of movement after brain injuries. Lorry (1760) first studied the condition of pigeons after puncturing the cerebellum. Schneider conducted the first experiments on weighing the brains of various animals. The positive role of the struggle of the revolutionary bourgeoisie at the end of the 18th century in France elevated France to the forefront with Lavoisier and especially Magendie, and it was here that the new science of Physiology of the 19th century first arose. The works of Lavoisier and Magendie thus not only completed the enormous work done by the brilliant constellation of French philosophers and scientists of the 18th century, who fought for a materialist understanding of life phenomena against any remnants of scholastic science of the feudal system, but also served as a foundation for further work in this direction. It is particularly necessary to note the role of the Paris Academy in the era of the Great French Revolution, which took the initiative in working on the strictly scientific study of a number of controversial questions in Physiology by announcing prizes. These included questions about animal heat, animal magnetism, and others. The works of Lavoisier and Laplace regarding the nature of animal heat, aimed at a chemical interpretation of physiological phenomena in the organism, formed the basis of modern concepts of metabolism and energy in animals, and the works of Magendie and especially his historical book 'Textbook of Physiology' marked the beginning of the objective experimental study of physiological processes. To the era of the Great Revolution also belongs the famous discovery of Galvani in Italy, which later provided the basis for the study of the Physiology of nerves and muscles. From France, new currents in the field of Physiology, resting on strictly scientific research of life processes, penetrated into other countries and first of all into Germany, where in the first quarter of the 19th century natural-philosophical physiology predominated and the experimental study of physiological processes was to a large extent in the background. At the end of the Great French Revolution, in an era of increasingly strong reaction, a new vitalistic direction emerged in the person of Bich (see Medicine and Vitalism). The following stages are characteristic for the third period: 1) The rapid growth of science and the extraordinary wealth of discoveries in the most diverse fields of Physiology in the era of bourgeois revolutions and the peaceful development of capitalism. 2) The return to idealism on the basis of 'physiological idealism' of the 19th century in the era of the decline of capitalism and its imperialist period as a reflection of the general 'tendency toward stagnation and decay,' characteristic of this epoch, in which 'to a certain extent the motivating causes for technical, and therefore any other, progress, forward movement' disappear (Lenin). 3) A powerful impetus for the new flourishing of Physiology on new foundations created in the USSR by the practice of socialist construction and ideological struggle in the direction of the dialectical-materialist development of its problems. The following main points are characteristic for this period: 1. The greatest successes of natural science as a whole made possible the emergence of Physiology as an 'exact science.' For Physiology, the decisive significance was first, the extraordinary development of organic chemistry, second, the appearance of the microscope, and also the three great discoveries of the 19th century: the proof of the transformation of energy, the discovery of the cell, and the formulation of the theory of the development of the organic world by Darwin. The main physiological schools were formed, which became the beginning of physiological schools worldwide. These include the schools of J. Müller, Ludwig, du Bois-Reymond, Helmholtz, C. Bernard. The basic regularities of physiological phenomena were discovered and formulated, which formed the basis of modern Physiology and became an achievement of theoretical natural science as a whole. Two directions of Physiology crystallized: idealistic ('physiological idealism') and materialistic (on the struggle of these currents-see Medicine). A close connection was established between Physiology and practical disciplines-medicine and zootechny-and the restructuring of scientific disciplines in these fields in accordance with the nature of 19th-century experimental Physiology (see Pathological Physiology). These areas had enormous significance for the development of Physiology itself (the role of clinical observations in the emergence and deepening of a number of chapters of Physiology, for example, endocrinology); they also played a major role in understanding individual physiological processes and in constructing a new field-Human Physiology. 2. The development and dissemination of a number of methods of physiological research (vivisection, physico-chemical, biochemical, physical, etc.) created an arsenal of modern physiological methods, which developed rapidly in the 19th century in parallel with progress in various fields of technology. Physiology separated from anatomy, special departments of Physiology were created in higher education, and special physiological laboratories were established in a number of countries, which became the embryos of major world schools of Physiology. Special periodic literature appeared and widely developed in all major countries of the world, covering questions of Physiology and related fields. Physiological societies emerged. International physiological congresses began to be systematically convened, uniting the work of physiologists worldwide. Intensive fragmentation of Physiology occurred and a number of so-called physiological disciplines arose on the most diverse bases: the application of one or another research method (chemical, physical, physico-chemical)-biochemistry, biophysics, electrophysiology; the expansion of material in individual chapters of Physiology-endocrinology; practical tasks of hygiene, rationalization of labor, agriculture: physiology of nutrition, Physiology of labor, zootechnical Physiology (these last physiological disciplines, created under conditions of capitalist development, underwent a complete restructuring in the USSR); by objects of research-so-called comparative physiology (zoological Physiology; partly physiological embryology). In the development of scientific problems of Physiology in the 20th century, the following key moments and directions can be schematically noted. 3. Major achievements in the field of synthesis of organic substances and the study of their chemistry (Wöhler, Liebig), 'the newly created organic chemistry, which learned to obtain from inorganic substances so-called organic compounds and thereby eliminated the last remnant of mystery of these compounds' (Engels). The works of Lavoisier, Wöhler, and Liebig formed the basis for creating a special direction in the field of Physiology-a direction represented today by biological chemistry (see). Hoppe-Seyler, Bunge, Hofmeister, Fischer, Kossel, and in more recent times Euler, Gulevich.

Willstätter, Abderhalden and others became the continuers of this chemical direction, creating our modern conceptions of the chemistry of substances both entering into the composition of living substance and specific to organisms: hormones, vitamins and enzymes, and finally the chemistry of processes occurring in the organism. At the present time, not only has a huge quantity of organic substances been synthesized, but also the synthesis of substances produced by specialized animal organs has been carried out, for example the synthesis of certain hormones (adrenaline, C70 thyroxin); the chemical nature of vitamins is being revealed and their similarity to some chemically known substances (carotenes) is being established, as well as substances of a vitamin nature have been artificially obtained (ergosterol); the chemical nature of enzymes is becoming increasingly clear, and the application of the purification method makes it possible to distinguish the role of the enzyme's active group and its carrier (see Enzymes). Works begun by Lavoisier in the most important area of P.—physiology of respiration, were carried on intensively further, and thanks to a number of the latest researches (Warburg, Meyerhof, Hopkins, Bach, Tünberg, Palladin, V. I. Wieland, Kostychev and others), modern P. has a strictly scientific conception of the chemistry of oxidation processes. Particularly great role was played by the discovery of oxidizing enzymes, self-oxidizing substances (in particular the discovery by Hopkins of glutathione), the discovery of the cellular respiratory pigment—cytochrome (Keilin); the description of experiments with oxidizing models, on the one hand, and the clarification of the role of cell integrity for respiration on the other; the detailed study of anoxiobiotic and oxybiotic forms of respiration, the relationship between these types of respiration and their distribution among different animals and finally the detailed research of the blood of various animals with regard to its capacity for oxygen saturation and dissociation, with regard to the regulation of blood carbon dioxide became that foundation on which modern teaching about respiration as a physico-chemical process rests. The experiments of Lavoisier and Laplace placed on a strictly scientific basis also the study of the process of metabolism in animal organisms and the question of the so-called animal heat, which before these works was considered as a special kind of life force. These works showed the energetic role of nutrients and laid the foundations for further works on energy exchange in the organism, on the one hand, and the mechanism of respiratory processes on the other. The one-sided energetic view of nutrients was later supplemented by Liebig's teaching on the plastic role of nutrients. In the direction indicated by the works of Lavoisier and Laplace and later Liebig, intensive work was carried out by a number of 19th century physiologists (Pflüger, Zuntz, Funt, Rubner, Atwater), which led to modern conceptions of nutrients as a source of the so-called animal heat and of the connection between the energetics of physiological processes and the law of conservation of energy. These strictly scientific achievements became possible only thanks to works in the field of organic chemistry and the discovery of the law of conservation of energy, and the complication and refinement of research methods of metabolism and energy in organisms made it possible to express in exact form the energetics processes of living organisms and their heat production. The most brilliant achievements of modern P., completing this circle of research in the part of heat production in the nervous system, are the works of the school of the Englishman Hill, who reached the limit of sensitivity of modern delicate instruments in determining heat production in muscles and nerves. The achievements of physiology in the 19th century forever decided the problem of animal heat in favor of its materialistic interpretation. The question raised by the latest idealists about the impossibility of an energetic, thermal evaluation of the work of the nervous system (Bunge) was clarified by modern works on the special chemical transformations in the nervous system during its work. The energetic direction in the study of metabolism processes somewhat pushed aside the study of the qualitative role of nutrients, which was begun mainly at the end of the 19th century (discovery of vitamins, clarification of the role of individual nutrients, in particular proteins, etc.); it is this side that is the central problem of metabolism in modern P. along with further research in the field of energetics of metabolism. In Germany, a prominent role belongs to J. Müller. His activity is connected with the end of the so-called natural-philosophical period in P. in the first quarter of the 19th century in Germany. This was to a large extent facilitated by the penetration from France of new ideas of experimental P., which was conducted by Magendie. The natural philosophers, engaged mainly in verbal, logical discussion of a number of physiological categories, thereby pushed the experimental method in P. to the background, and in their interpretation physiological phenomena appeared in a mystified, incomprehensible form (analogizing animal organs with individual lower animals; interpretation of animal magnetism in the teaching of polarity, etc.). But Engels rightly noted that although in the old natural philosophy 'there are many absurdities and extravagances, however, no more than in modern non-philosophical theories of empirical naturalists, and alongside this it contains much that is serious and reasonable, as has been recognized since the spread of the theory of development. Thus, Haeckel with full right recognizes the merits of Treviranus and Oken. The latter in his teaching on the original slime and the first bubble put forward as a postulate of biology what was later discovered in the form of protoplasm and cell'. The German natural-philosophical school undoubtedly had a positive significance in the setting of a whole series of theoretical problems of biology. It is this positive side that had its influence on J. Müller, this greatest physiologist-thinker. He managed on a broad basis to develop enormous experimental work both in the field of P. and in other fields of biology and on this basis created a school from which came all the most prominent founders of P. of the 19th century. Being a philosophical follower of Kant, J. Müller, proceeding mainly from the law of specific energy of senses formulated by him, created a system of the latest idealism in P., the so-called physiological idealism, against which L. Feuerbach polemicized. The idealism of Müller consisted in that, in investigating the mechanism of our sense organs in their relation to sensations and pointing out for example that the sensation of light is obtained from various kinds of effects on the eye, he was inclined to deny that our sensations are images of objective reality. This tendency towards 'physiological idealism', i.e. towards an idealistic interpretation of known results of physiology, L. Feuerbach grasped extremely aptly. 'The connection of physiology with philosophical idealism, predominantly of the Kantian type, was for a long time afterwards exploited by reactionary philosophy' (Lenin). This side of the teaching of J. Müller played an enormous role in the further development of idealistic tendencies in P. up to our time, which is especially vividly represented in the works of the modern idealist physiologist Ikschul. J. Müller in his concrete work showed the whole importance of comparative-physiological researches, becoming the founder of this direction in modern P. He compiled a two-volume textbook of human physiology, which played a major role in the history of P. The pupils of J. Müller—Du Bois-Reymond, Helmholtz, Ludwig, Virchow—set out on the path of physical and physico-chemical direction in the investigation of physiological phenomena and achieved enormous results in this respect. To the period of activity of these scientists belongs the formulation of the law of conservation of energy by R. Mayer-Helmholtz; the discovery of the cell, the study of the basic properties of the neuromuscular system; the beginning of works in the field of P. of sense organs on the basis of physical laws of optics and acoustics and others. Du Bois-Reymond and Helmholtz created modern electrophysiology. In France, the continuer of the line begun by Magendie was Claude Bernard, who laid the foundation for the wide application of the vivisectional direction. Being a brilliant experimenter, he made a number of greatest discoveries in the field of physiology. The works of these greatest scientists, having enormous positive significance in their concrete historical situation, determined however for a long period the purely mechanical direction in the analysis of physiological processes, and this together with the energetic approach to the study of metabolism in the organism and the study of physiological processes of isolated parts of the organism created that theoretical level of P., which characterizes P. of the second half of the 19th century and the bearer of which were the so-called vulgar materialists (Büchner, Vogt, Moleschott and others). 'After the regime of Hegelian diadochi, which led—writes Marx—to the domination of pure phrase, naturally came the epoch in which the positive content of science again outweighed its formal side.'

But at the same time, Germany threw itself with exceptional energy into the study of natural sciences, which corresponded to its powerful bourgeois development since 1848; and as these sciences came into fashion, in which speculative direction never achieved great importance, the old metaphysical manner of thinking also spread again, up to the most extreme limits of Wolffian vulgarity. Hegel was forgotten, a new natural-scientific materialism developed, which theoretically differs in no way from the materialism of the 18th century and has for the most part only the advantage that it has at its disposal a richer natural-scientific, namely chemical and physiological, material. We find brought to the greatest plane of reproduction this organic philistine way of thinking of the pre-Kantian period in Büchner and Vogt; and even Moleschott, who blindly believes in Feuerbach, gets amusingly tangled up in the simplest categories every minute. The clumsy draft horse of ordinary bourgeois reason of course stops in perplexity before the ditch separating essence from phenomenon, cause from effect, but when they go hunting with hounds in a field extremely furrowed with ditches of abstract thinking, then one cannot exactly sit on draft horses. By the end of the 19th century, purely thermodynamic approaches to understanding physiological processes were widely used, the incorrectness of which Engels timely signaled. 'It seems that some scientists would not be averse to transferring the thermodynamic category of work back into political economy, as is done in the Darwinian struggle for existence, and in the end only nonsense would result. Let them try to express some skilled labor in kilogram-meters and try to determine on this basis the wage. From a physiological point of view, the human body contains organs which can be considered in their aggregate as a thermodynamic machine that receives heat and converts it into motion. But, assuming the conditions of the other organs of the body to remain unchanged—the question is, can the physiological work produced—even the work of lifting—be exhaustively expressed simply in kilogram-meters. After all, internal work is taking place in the body at the same time, which does not manifest itself in the external result, after all the body is not simply a steam machine experiencing only friction and wear. Physiological work is possible only with the presence of constant chemical transformations in the body itself and it also depends on the process of respiration and the work of the heart. With each contraction and relaxation of the muscle, chemical transformations take place in the nerves and muscles which cannot be equated with the transformations of coal in a steam machine. Of course one can compare two physiological works occurring under otherwise equal conditions, but one cannot measure the physiological work of a human being according to the work of some steam machine etc.; one can compare their external results, but not the processes themselves, unless one makes serious reservations in this connection' (Engels, Dialectics of Nature, pp. 38-39).-Du Bois-Reymond, having done enormous work in the struggle against idealism, then slid into agnosticism, proclaiming the famous 'Ignorabimus'. Helmholtz, 'the greatest figure in natural science, was inconsistent in philosophy, as was the vast majority of natural scientists. He inclined toward Kantianism, but even from this point of view he could not hold consistently in his gnoseology'. Helmholtz's doctrine of sensations as signs or symbols having no resemblance to things played a major role in the further struggle of the idealistic and materialistic directions in gnoseology (see Lenin, Materialism and Empiriocriticism). The works of I. M. Sechenov played an enormous role in the materialist understanding of this question, and at the present time, in view of the exceptional acuteness of the question, the questions of the physiology of sense organs are one of the most pressing problems of modern P. and especially Soviet P. Created by the works of Du Bois-Reymond and Helmholtz on the basis of the works of Galvani, Volta, Matteucci, the electrophysiological direction in P. at the present time has achieved enormous results in terms of the fineness of research, as well as in terms of the large amount of factual material collected. Thanks to the works of major physiologists of the 19th century (Pflüger, Fick, Hermann, Fletcher, Engelmann, Bernstein) '73 the chapter on the physiology of muscles and nerves was comprehensively developed, and the foundation was laid for the study of the physiology of the act of movement as a whole. Modern P. seeks more and more adequate biological stimuli for stimulation, understanding the limited significance of electric current as a source of stimulation; more and more are being revealed the specific features of the processes taking place in the nerve fiber and muscles, and besides electrical phenomena, the chemeodynamics of nerve conduction and muscle contraction are studied (see Muscles, Nerves). Through the works of Lucas, Lapique, Vvedensky and Ukhtomsky, the intimate sides of the processes of excitation in the nervous system are revealed, in the modern doctrine of chronaxy (see), in Vvedensky's theory of parabiosis (see), in the law of 'all or nothing' (see), in the doctrine of decrement etc. The experimental-vivisectional direction, brilliantly begun by the French physiological school, received worldwide development and is represented in modern P. by a whole series of new methods for investigating the living: the method of isolated organ survival (Kravkov), the method of tissue cultures (Carrel), methods of microscopic research of physiological phenomena in living organs and tissues etc. A special place is occupied by the further development of the proper vivisectional direction, which thanks to the works of Heidenhain and especially I. P. Pavlov grew into a new surgical direction, allowing the investigation of processes in the normal, recovered from operation animal. Pavlov's discovery of conditioned reflexes placed the study of the physiology of higher nervous activity on a completely new basis. Thanks to the works of Bayliss, Starling and Pavlov, the problems of neuro-humoral regulation in the organism were raised. The most complex problem of the integrative role of the central nervous system was posed and developed thanks to the works of Sherrington, Pavlov, Magnus (see Magnus-Klein reflexes). Finally, it is necessary to specially note that with chronological delay, it was only in the 19th century that questions were first posed in the direction of the evolutionary development of P. In studying the regularities of function in the 19th century, P. fought for the knowledge of the physics and chemistry of life processes, but, being historically a necessary progressive stage in the development of P., this period at the same time contained the germ of a delay in the development of science in the future, which expressed itself in the divergence of the paths of P. and morphology, P. and evolutionary science, which has not yet been overcome to the present day. Only _: from the beginning of the 20th century are questions of general comparative P. and comparative P. of farm animals systematically developed; questions of P. and biochemistry in the ontogenesis of animals are intensively developed; questions of a new field of P.—'paleophysiology', P. of extinct forms (Ya. Samoylov, 1917; Wilser, 1932), are raised, and finally a number of major biologists-morphologists and physiologists pose the problem of evolutionary P. (Severtsov, Lucas), in the direction of which concrete research is being carried out by some workers only in recent years. All these characteristic 20th-century physiological problems are problems of a synthetic order, in contrast to the prevailing analytical direction of 19th-century P. The processes of the organism as a whole in their connections, in their individual and historical development stand in the field of view of modern P. On a truly scientific materialist basis, these tasks are posed and resolved by Soviet physiologists. This ensures the USSR and in the future a leading place in world P., achieved by the works of Acad. I. P. Pavlov. Physiology in the USSR. The roots of Soviet P. go back to a number of physiological schools of the 19th and early 20th centuries in Russia. The founder of Russian P., which rose to the level of European science, is undoubtedly I. M. Sechenov, he was also the creator of a group of major student-professors of P. (V. V. Pashutin, Voroshilov, Tarkhanov, N. E. Vvedensky, N. P. Kravkov, S. S. Salazkin, M. N. Shaternikov, A. F. Samoylov). In the creation of the Leningrad physiological school, the role of F. Tsion—teacher of Acad. I. P. Pavlov—must be noted; of the Kazan school—G. I. Kovalovsky. The historical role in the development of Russian P. belongs to Acad. I. P. Pavlov, who created a numerous school of physiologists who are the leading workers of Soviet P. (I. S. Tsitovich, L. A. Orbeli, V. V. Savich, N. A. Rozhansky, G. V. Folbort, P. S. Kupalov, K. M. Bykov, I. P. Razenkov, A. I. Smirnov). Through the works of Sechenov, Tsion, Kovalovsky and especially Pavlov, the first physiological laboratories in Russia were created, by them the foundation was laid for the scientific-experimental development of questions of P. (vivisectional, physico-chemical, physiologo-chemical) in contrast to Russian P. of the first quarter of the 19th century with its low level. Basically, being students of the great figures of the German physiological school (Ludwig, Du Bois-Reymond, Heidenhain), they transferred to Russia the best sides of the exact experimental direction in the development of P. in Europe.

The works of Sechenov and Pavlov outlined the specific features of the development of Physiology in Russia. This was, first and foremost, in the field of theory—a clear, uncompromising struggle against idealism in the study of problems of behavior; thanks to this, the foundation was laid for a strictly scientific Physiology of the central nervous system, and in the field of practice, an organic connection was established between Physiology and clinical medicine, with the development of physiological questions in connection with the tasks of medicine. The significant role in the further development of Physiology in various centers of Russia was played by N. E. Vvedensky (Leningrad), A. N. Mislavsky (Kazan), and A. Ya. Danilevsky (Kharkov). The creation of distinctly expressed schools, developing their own special problems, is associated with the names of these scientists. It is particularly necessary to note the role of N. E. Vvedensky, who gave a great impetus to the in-depth development of problems of neuromuscular Physiology not only in Russia but also beyond its borders. A direct continuer of Vvedensky's work is A. A. Ukhtomsky—the head of the physiological school of Leningrad University, developing the fundamental problems of neuromuscular and central nervous system Physiology. One of Pavlov's oldest students, L. A. Orbeli, created a whole series of works in the field of Physiology, little developed in Russian Physiology before him (vegetative nervous system; excretion; central regulation of coordinated acts, etc.), laying the foundation for one of the leading schools of Soviet Physiology. A major role in the development of the most precise methods for studying muscles and nerves was played by A. F. Samoylov. Work in the field of gas exchange and Physiology of nutrition was established and developed by M. N. Shaternik and his students. New areas of research in Soviet Physiology were outlined and developed by L. S. Stern in the Institute of Physiology of the People's Commissariat for Education (Narkompros) organized by her (the problem of oxidation, the problem of the hemato-encephalic barrier). Independent significance belongs to the works of P. S. Beritov and his school, working on problems of the Physiology of the nervous system and animal behavior. The works of V. Yu. Chagovets and P. P. Lazarev laid the foundations for the physico-chemical development of physiological problems, in particular problems of excitation (see Ionic theory of excitation). The enormous group of questions raised and posed by Pavlov is further developed by his closest students: questions of digestion (Razenkov, Folbort), questions of trophics (Orbeli, Speransky), questions of conditioned connections in the organism (Anokhin, Andreyev, Asratyan, Bykov, Nikitin, Petrova, and others). In the time since the October Revolution, Physiology in the USSR has achieved enormous success in both theoretical work and scientific organization. The tasks of socialist practice (socialist livestock breeding, Soviet medicine) have opened up completely new areas, previously undeveloped in Russia: zootechnical Physiology (M. and B. Zavadovsky, Krzhishkovsky, and others), questions of Physiology of labor and Physiology of nutrition; Soviet science has posed before Physiology a number of new theoretical problems, which stimulated the development of new sections of Physiology, such as comparative, embryonic, and evolutionary Physiology (Orbeli, Koshtoyants), the problem of human Physiology, questions of Physiology of the sense organs, questions of genetics of higher nervous activity, questions of thermodynamics and chemodynamics of muscles and nerves, etc. On the territory of the USSR, many specialized physiological scientific research institutes were opened, which in old Russia numbered only a few. Extensive measures for the training of graduate students created a large number of new physiologists. Thus, at the I Congress of Physiologists in 1917, there were only several dozen participants, while at the V Congress in 1934, there were about 700. In addition to the central schools and laboratories mentioned above, scientific work in physiological institutions of a number of cities of the Union was organized and is intensively developing. The opening of a wide network of physiological laboratories of the Institute of Livestock Breeding of the Lenin Academy of Agricultural Sciences, the development of a vast network of physiological and related laboratories in the VIEM, special resolutions and measures to ensure the work of Academician I. P. Pavlov and his staff constituted the organizational basis on which the flourishing of Physiology in the USSR became possible, activated by the theory and practice of socialist construction. Physiological congresses, congresses, conferences. International congresses. Starting from 1888, at intervals averaging 3 years, international physiological congresses have been held, uniting the work of physiologists, biochemists, and pharmacologists. From 1888 to the present, 15 congresses have taken place in various centers of Europe and America. The last (XV) international congress was held in Leningrad and Moscow in August 1935. International physiological congresses are the most authoritative and numerous among other biological congresses. At the XIV Congress (1932, Rome), there were 1,200 participants, and at the XV Congress (1935, USSR), the number of participants reached 1,600 people. The number of participants from the USSR at the congresses increases from congress to congress. International physiological congresses have enormous significance as an organization facilitating acquaintance and mutual discussion of individual questions developed by various scientists in the most diverse countries of the world. The proceedings of the congresses, which usually appear in the form of a special issue of a physiological or biological journal of the given country, are of great importance. The supreme body of international physiological congresses is a permanent organizational committee with representatives of some countries (USA, France, England, Germany, Italy, Sweden, USSR) numbering 7 people. A representative of the USSR—Academician I. P. Pavlov—is included in its composition. The question of the place of the congress is decided by the plenum of the congress. For specific work on the organization and conduct of international congresses in the respective countries, a special organizing committee for convening the given congress is elected from physiologists of that country. Congresses and conferences in the USSR. On April 6-8, 1917, the I Congress of Russian Physiologists named after I. M. Sechenov was held in Leningrad. At this congress, a decision was made to work on the newly organized Society of Russian Physiologists named after I. M. Sechenov, and elections for the board of this society were held (see below); a decision was made to publish a new journal—the 'Russian Physiological Journal named after I. M. Sechenov'—and the regulations for this journal were approved. In addition, the I Congress of Physiologists adopted a special resolution on the report of Prof. B. I. Slovtsov 'The participation of physiologists in questions of population nutrition,' in which the necessity was noted of 1) creating a commission for the collective development of questions of nutrition and 2) 'establishing a scientific institute for the planned development of questions of nutrition.' The II Congress of Physiologists was also held in Leningrad in 1925; the III Congress—in 1928 in Moscow; the IV Congress—in 1930 in Kharkov; the V Congress—in 1934 in Moscow. The number of participants at the congresses sharply increases from congress to congress: thus, at the III Congress there were about 450, and at the V Congress—about 700 participants. A number of major foreign scientists participated in the All-Union Congresses of Physiologists. The proceedings and materials of the congresses (II, III, IV, and V) were published in a special edition in the form of 'Proceedings.' At the III Congress (1928), the Statute of the All-Union Association of Physiologists was adopted. At the V Congress (1934), the Board of the All-Union Society of Physiologists was elected. Regional congresses. In addition to all-union congresses of physiologists, congresses of physiologists of individual republics and regions are also convened. Thus, in 1929, the I All-Ukrainian Congress of Physiologists was held, in which about 200 members participated. The congress, in addition to hearing and discussing special reports, paid great attention to discussing problems of Physiology in connection with the tasks of public nutrition. The work of the congresses of Caucasian physiologists is particularly intensive (since the end of 1926 there have already been five). The last (VI) congress was convened in Erivan in October (October 11-17) 1934. This congress brought together many workers from the RSFSR and Ukraine and to a large extent exceeded the size and significance of a regional congress. Conferences on specific questions. In addition to the periodic convening of all-union, republican, and regional congresses, discussing a number of questions, conferences on specific physiological problems are also convened. These include conferences on questions of labor physiology; conferences on questions of nutrition (1928); conferences on the problem of protein and protein metabolism (1933); on carbohydrate metabolism (1933); the 1st meeting on problems of comparative Physiology (1934) and many others. Societies of Physiologists. There are a number of specialized physiological societies in major countries of Europe, America, and Asia. The statute of the first Society of Russian Physiologists named after Sechenov was approved on November 16, 1916. The Society of Russian Physiologists named after Sechenov, which published its works ('Proceedings of the Society of Russian Physiologists named after I. M. Sechenov'), existed as such until 1930, after which, in connection with the development of activities of local physiological societies in major centers, republics, and regions and the decision of the III All-Union Congress of Physiologists to organize branches of the republican society, it continues to work as the Leningrad Society of Physiologists named after Sechenov. A large, intensively working Society of Physiologists, Biochemists, and Pharmacologists was organized in 1928 in Moscow. There are societies in Ukraine (with a network of branches), in Byelorussia, Transcaucasia, in the North Caucasus, and others.

After the V Physiological Congress, the work of local societies is united by the board of the All-Union Society of PHYSIOLOGISTS.

X. Koshtoyants. Physiology of labor—a differentiated branch of general physiology, as well as labor hygiene, studying the physiological changes in the human body caused by the process of labor, and setting as one of its tasks the organization of labor in accordance with the requirements of physiology. The subject of its research is all types of labor, primarily labor with a predominance of muscular activity, causing greater shifts in the physiological functions of the body than so-called mental labor. The competence of labor physiology includes mainly industrial labor, then construction, agricultural, military, etc. Departments of labor physiology are distinguished either by systems of the body: physiology of circulation and respiration, energetics of labor, physiology of sense organs, central nervous system, physiology of labor movements and biomechanics, or by the problems studied. In particular, it studies the problems: physiological professional selection, professional training and training, performance and fatigue, physiology of rest. The role of age, typological and individual differences is studied in all departments. Labor physiology is closely adjacent to a number of sciences, in particular to labor psychology or psychotechnology (see), since with the increasing mechanization and automation of labor processes, the role of the central nervous system, especially the cerebral cortex, increases at the expense of the direct activity of muscles, cardiovascular, respiratory and other autonomic systems. Labor physiology is inextricably linked with labor hygiene (in particular, in medical schools it is taught in the latter's course), since all labor processes must be organized so as to give maximum productivity with the complete absence of harmful effects on health and with the maximum development of all physical abilities inherent in man. In technology, the conclusions of labor physiology are used in technical standardization, safety engineering, and partly in mechanical engineering. The medical clinic is very interested in labor physiology, since many diseases of the circulatory, musculoskeletal and nervous systems are the result of improper organization of labor, overload, overwork. The connection of labor physiology with medical sciences is constantly growing as labor physiology itself develops. As an example, one can point to the importance of the physiology of labor movements and biomechanics for anatomy, orthopedics, surgery, neuropathology, etc. The history of labor physiology can be traced back to the early years of the 20th century, when I. M. Sechenov published his famous "Outline of Labor Movements of Man", but even before that he wrote a number of works in which the role of sense organs in the process of labor was analyzed. Generally speaking, before Sechenov, professional labor did not attract the attention of physiologists, and only walking and marching were studied from a biomechanical (Braune and O. Fischer) and energetic (Zuntz and Schumburg) point of view. In 1905-15, professional labor interested the Frenchmen Imbert and Amar, who systematized in their book "Le moteur humain" a significant part of the facts obtained by physiology up to that time. The term "labor physiology" appeared later, when labor physiology itself took shape as an independent discipline with its own methods, problems and approaches. An institute of labor physiology was created in Berlin by E. Atzler and G. Lehmann, which was later moved to Dortmund, closer to the Ruhr area, the industrial center of Germany, where it now serves the interests of large industrialists, by whom it is mainly maintained. Interest in labor physiology from industrialists in all countries arose during the war, when the issues of intensification of labor were particularly acute in connection with the unprecedented demands of the fronts, and when women, the elderly and adolescents were attracted to factories and plants. In England, the "Committee for the Study of Industrial Fatigue" (Vernon and others) was organized; in France, on smokeless powder plants, the research of Marcel Frova and his colleagues was conducted, and the disabled war veterans were studied by Amar using dynamometric and energetic methods. After the end of hostilities, the issues of professional selection and retraining of demobilized persons arose with particular sharpness, but labor physiology proved unprepared for their scientific resolution. The capitalist rationalization of industry, caused by competition between states and within them, set before labor physiology the task of maximizing the productivity of the worker. From this point of view, many studies were conducted in Germany and England, and from this point of view are connected the mechanistic views of man as a machine and the ignoring of the social aspect in labor. In England, the USA and France, there are no special laboratories for labor physiology, and besides Germany, only Japan has a special institution in the center of the textile industry, in Kurashiki, where psychological and physiological research is conducted. In Russia, the first institute of labor (Society of Scientific Institute) was established as early as 1916 as part of the economic and physiological (headed by Prof. V. A. Anri) departments. From here came the first labor physiologists. After the 22 October Revolution, the issues of labor physiology began to be developed at the Moscow Psychoneurological Institute (1920-25), at the Central Institute of Labor of the All-Union Central Council of Trade Unions (1921-25), at the Institute of Labor Protection (from 1925), in institutes of hygiene and pathology of labor in Moscow, Leningrad, Kharkov and other cities of the Union, and in numerous laboratories and institutes (NKPS, NKZdr., NKSO, military department, etc.). The Institute of Nutrition (Prof. M. N. Shaternikov and O. P. Molchanova) carried out enormous experimental and systematic work, developing and collecting a number of standards for food rations and data on energy expenditure in various types of industrial work (metal processing, construction work, chemical industry, agricultural work, etc.). Among the known workers in the field of labor physiology, the following should be mentioned: N. A. Bernstein, who created an original school of biomechanics and developed a number of interesting methods for studying movements; M. I. Vinogradov (Leningrad University), who trained a large number of young labor physiologists; E. M. Kagan, head of the physiological laboratory of the All-Ukrainian Institute of Hygiene and Pathology of Labor; S. I. Kaplun, theorist of labor physiology, organizer of the Central Institute of Labor Protection; K. X. Kekechev, head of the department of labor physiology at the All-Union Institute of Experimental Medicine; M. E. Marshak, whose attention is mainly directed towards the study of the environment and its influence on the labor process; E. Simonsen, a German physiologist who has been working in the Ukrainian SSR for many years; and D. I. Shatenshtein, head of the physiological laboratory of the NII RKKA. Thus, Soviet labor physiology is the strongest both in terms of the number of research institutions and workers, and in terms of the number of publications, and the breadth of problem-setting and the depth of research by Soviet physiologists distinguish them, as shown below, from foreign scientists. Labor physiologists do not have their own independent scientific society; in the USSR they are united in sections of labor physiology or human physiology of the corresponding republican or regional branches of the All-Union Society of Physiologists. At all-union congresses of physiologists (1926, 1928, 1930 and 1932), large sections of labor physiology worked, and dozens of special reports were read, testifying to intensive research work in the USSR. At the International Congress of Physiologists in Leningrad in 1935, a section of labor physiology worked, where out of 8 reports, 7 belonged to Soviet delegates. Teaching of labor physiology. In medical schools, there is a small theoretical and practical section of labor physiology in the course of labor hygiene; at biological faculties in Moscow and Leningrad, special departments operate, where pedagogical and research work with graduate students is also conducted. The question of the profile of a labor physiologist specialist has not yet been finally resolved: should he necessarily be a doctor, or can he become a labor physiologist only after graduating from a biological faculty. The current state of labor physiology is determined ideologically by the refusal of Soviet physiologists to adopt mechanistic approaches, which prevail abroad and which still recently existed in our USSR. The view of the working person as a machine, a mechanism, the attempt to regulate his labor on the basis of energy data and the coefficient of efficiency, the ignoring of the social nature of human labor, the underestimation of psychological and social factors determining a person's capacity and performance, the misunderstanding of the role of the Stakhanovite movement and socialist competition—all these are the errors that were inherent in almost all workers in labor physiology until 1931 and which have been basically overcome by Soviet labor physiology. Abroad, however, due to the bourgeois nature of this science and the corresponding social orders and the complete helplessness of labor physiologists in the field of philosophy, mechanistic or idealistic views are often encountered. Methodology and problematics are closely related here, and therefore in the USSR the approach to the problems of labor physiology is fundamentally different than abroad.

The main problem is the problem of work capacity and labor standardization, which in its physiological interpretation is closely related to the problem of fatigue (see). The problem of work capacity and fatigue is most closely related to the problem of rest and physiological recovery processes in the body (the effect of rest on a fatigued person, passive and active rest, the role of emotions, dosage of rest, work and rest schedules, etc.). The problem of typical and individual variations in work capacity is only just beginning to be outlined in the physiology of labor due to the underdevelopment of differential physiology. Its significance for the physiology of labor is enormous, since people of different constitutional types and personalities react quite differently to various types of labor. Also little studied is the so-called physiological professional selection; similar in content to it are the psychotechnical and medical professional selection and professional orientation, which have been developed more or less in detail (see Professional selection). In connection with the problems of typical and individual variability and the problems of physiological trainability and work methods stands the problem of the 'quality' of work; physiologists studying this problem aim to identify the physiological causes of production defects and ways to improve product quality, taking into account socio-domestic factors in their analysis. Finally, one of the most important problems of the physiology of labor is the problem of learning, considered from a physiological perspective—trainability (see). The process of acquiring skills is currently studied only from psychological and pedagogical points of view, yet the education of movements and corresponding vegetative systems, and the training of the organism, almost entirely fall within the competence of the physiology of labor. Accelerating the learning process and better fixation of acquired skills are of great interest to schools where professional labor training is conducted. Finally, the problem of the workday schedule, rest, and labor standardization, one of the most difficult and complex problems in the physiology of labor, is currently at the center of its attention. From what has been presented, it is clear that all the problems of Soviet labor physiology are very relevant from the point of view of the interests of socialist construction, and at the same time represent a very great theoretical interest.