Pavlov, Ivan Petrovitch.
Biography and scientific activity.

(By Victor Klimenko,  head of the Pavlov Department of Physiology  and
 Jury Golikov,  Head of the History Museum, Institute for Experimental Medicine)

(Ivan Petrovitch Pavlov was born in the priest family in the town of Ryasan on September, 26, 1849. His father Petr Dmitrievitch (1823 – 1899) was a well educated person. His mother Varvara Ivanovna (1826 – 1890) came from the priest family, too. I.P. Pavlov was the eldest son among 9 children, though 5 of them died early. Pavlov obtained contemporary education at a cleric seminary.

Pavlov was deeply influenced by the ideas of Russian democratic writers (Belinskiy, Pisarev, Tchernishevskiy, Dobrolubov) and by the studies in physiology by H. Lewis, L. Herman and, especially, by I.M. Setchenov. To pursue this new interest he entered St. Petersburg University, the faculty of mathematics and physics, the department of natural science. Pavlov’s scientific activities started at the University under the guidance of Prof. F. Ovsiannikov and Prof. I. Tsion, in the field of physiology of digestion.

In 1875 Pavlov got his Ph.D. at the University and entered Medical and Surgical Academy as a third year student (in 1881 it was turned into Military Medical Academy (MMA)). Studying at the Academy he went on with his experiments in physiology under the guidance of Prof. K. Ustimovitch. Being acknowledged as a masterful experimenter Pavlov was invited by famous Russian internist Prof. S.P. Botkin (1878-1890) to work at the Laboratory of Physiology, which was a part of the Clinic of Internal Medicine headed by Botkin. Pavlov both carried on with his scientific studies there and guided the work of a group of students.
After his cum eximia laude graduation from the Academy Pavlov was given a position at the Institute of Doctors (a part of the Academy) and later on he was sent abroad for 2 years to develop his skills and widen his knowledge.

On May, 25, 1881 Pavlov married Serafima Karchevskaia (1859 – 1947), a daughter of a navy doctor. He and his wife had 4 children, and his attitude towards the family was most serious: he insisted on all his children being well educated.
Pavlov’s wife was the only religious member of the family. Being an atheist Pavlov at the same time was very tolerant and often gave a hand to people paying no attention to the confession they belong to.
Pavlov brought his love for fine arts into family: he owned a large library and a good collection of paintings. They all liked music, and musical parties were a regular event in the drawing room of their flat.

During his two-year stay abroad ( Leipzig and Breslau) Pavlov studied theories and researches by prof. R. Heidenhain, K. Ludwig, and others. On his return to Russia he literally became the head of the laboratory at MMA. He worked in that small laboratory for 10 years. His own scientific data accumulated during this period he presented as his Doctoral Thesis “Centrifugal Nerves of the Heart” (1882). After that he turned to his study of physiology of digestion again. At the same time he delivered two lectures to the students as probation and was given a position of Private-docent at the Department of Physiology (MMA).
1886 – 1890 was a very fruitful period for Pavlov. Though he had no officially assigned assistants and was armed with new ideas and with his personal charisma only, Pavlov carried out scientific studies of a great value. He was the first to demonstrate that the heart and lungs, when taken as a whole complex from the animal, and connected with special tubes in particular sequence could not only function for quite a long time, but also could be used as a model to test effects of medicines.
On December, 1, 1888 Medical Faculty of Warsaw University awarded Pavlov with the Prize of Adam Hoinatsky for his work “Centrifugal Nerves of the Heart” based on the materials of his Doctoral Thesis. The Prize was Pavlov’s first scientific award.
In 1888 and several times later Pavlov applied for the position of a Professor, basing his request on the fact that to devote all his time to scientific research he would like to be provided for. Otherwise he had to be engaged in other medical or tutorial activities to earn his living. He was ready to head any experimental department in any Russian university. At the same time he carried on his investigations in Botkin’s clinic laboratory studying the functions of pancreas and stomach. He also started to operate on dogs using method of implanting fistulas into stomach and developed further R. Heidenhain’s method of miniature stomach.

On April, 24, 1890 MMA Conference elected Pavlov as Professor of Pharmacology Department. Almost at the same time Prince Oldenburg suggested that he would participate in a new research institute organizing. Pavlov accepted the offer and in 1891 was appointed the Head of the Physiology Department of the Imperial Institute for Experimental Medicine (IIEM), whose founder and trustee was Prince Oldenburg.
It was only in 1895 that Pavlov, being 46 years old, became the Head of the Physiological Department of the Military Medical Academy. He occupied this position from 1895 till 1925. It is accepted commonly now, that the Department has significantly influenced the development of experimental physiology in Russia His talent was sincerely admired by students and was acclaimed by scientists all over the world. Students, doctors undergoing specification courses, adjuncts were Pavlov’s vast resource of staff and of freelance assistants. They all performed their studies in IIEM, where all conditions necessary for scientific work were provided.
Pavlov started organizing the Department of Physiology (IIEM) in January, 1891. In December of the Department’s first year report contained the results of the research which revealed a significant role of the liver in transformation into neutral compounds of those poisonous chemicals which were originated in the body during the process of food decomposition.

In October of 1893 the concern “Nobel Brothers” sponsored the IIEM with 10.000 roubles and in 1894 a two-floor stone extension to the main building was constructed. On its ground floor there were rooms for chronic experiments, on the first floor there was a superb surgery and a clinic for keep of operated dogs. It was for the first time that physiologists had under their command a surgery as good as the ones in the best clinics of that time. It was a great outcome of Pavlov’s efforts. In the IIEM where conditions for scientific work were better in comparison to MMA Pavlov, his apprentices and colleagues organized a broad front of work in the field of physiology of digestion which laid the foundation for his scientific school and resulted in a theory of digestion mechanisms. He also explained the role of vagus and sympathetic nerves in production of gastric and pancreas secretion.

The results of the study of physiology of digestion were presented in the cycle of 7 lectures delivered by Pavlov to scientific and medical community. Those lectures were an important step in systematisation of vast information on nervous regulation of the digestive glands activities, on the laws ruling the production of digestive juices, on interaction of the stomach secretion with liver, pancreas, small intestines functioning, as well as with the functioning of other parts of digestive tract.
Pavlov demonstrated that wide use of experimental surgery in chronic experiments on animals gave an opportunity to investigate interactions of the digestive glands activities and mechanisms of their functioning. It was a new line of studies in digestion: exploration of physiological mechanisms of digestive glands activities under conditions of chronic experiment on a healthy animal with integral and continuously working digestion system. All his achievements in this field Pavlov summarized in his book “Lectures on the Work of the Chief Digestive Glands” (1897). In this book he added the eighth lecture to delivered previously seven ones – “Physiological data, human instinct and medical empiricism”. A year later the book was published in German being translated by his pupil A. Valter.

By 1904 when Pavlov was awarded with the Nobel Prize he had been engaged in scientific and pedagogical activities for 25 years. His studies made a large impact on the scientific community – never had physiology helped clinic medicine so significantly. In his lectures Pavlov regarded the process of digestion as a physiological conveyer which combined separate organs of digestive tract into a system. Such approach helped to create complete picture of digestion.
Attention of the Nobel Committee played a significant role in the increase of his prestige in scientific world. Before publication in press of the announcement about Pavlov as an expected Nobel Prize winner had been a member of 6 scientific societies (including 2 foreign ones), and in 1904 he was on the lists of 32 societies. This process, of course, was facilitated by appearance of the first Nobel Prize winner from Russia. It was in 1904 that Pavlov’s 25th anniversary of scientific activities was celebrated. His teacher Prof. I. Tsion wrote in his letter of congratulation: “I especially appreciate in your scientific work that being the Head of the well-equipped laboratory in IIEM …. You stayed faithful to your conviction that only experimental physiology can serve as a foundation of scientific medicine.”
By that time Pavlov and his numerous pupils had obtained new facts which initiated further development of the main ideas of the “Lectures”, clarifying them, or even led to reconsignment of some in the light of new data.

Talking about Pavlov’s contribution to the development of methods used for digestive glands investigation it is necessary to emphasise that introduced innovations not only developed existing fistula methods but also created a possibility of integral exploration of physiological processes. Using a health animal, with normal interactions with environment it became possible to study either functioning of salivary or gastric glands, or work of pancreas (according to the experimental task set), or their interaction in the framework of the normal digestive process.
An important chapter in Pavlov’s school studies was devoted to the investigation of chemical agents which cause gastric glands secretion when acting from stomach cavity (stomach phase of secretion). By the time when “Lectures” were wrote Pavlov and his colleagues had been the first to demonstrate irritating effect of meat extracts and of peptone peptide (product of digestion) on gastric secretion.

While studying the effects of food components on the gastric glands functioning scientists of Pavlov’s Department revealed that fat influences it as an inhibitor. “We face a new and to a high degree acute fact: fat inhibits, slows normal energy of the secretion” – Pavlov wrote.
Fundamental facts obtained in Pavlov’s laboratories are of everlasting significance. It is even more important that discoveries made by Pavlov and his school in the field of digestion, which contributed to the glory of Russian science, gave a powerful impetus for detail exploration of the digestive tract secretion regulation both in Russia and abroad. They outlined the main directions of investigation for many oncoming years. Following them new studies showed the role of nervous system in digestive functions regulation, on the one hand, and revealed the significance of humoral mechanisms, on the other hand.

Pavlov’s works in the field of physiology of digestion gained the highest international recognition. They compose a complete cycle of systemic studies. At the same time they were a starting point for a new vast series of investigations, which laid a ground for creation of a new, never existed field of physiology: HNA (HNA), or theory of conditioned reflexes.
The scientific report of the Department of Physiology (IIEM) for 1903 reads: “Besides investigation of digestive channel secretion and of different types of digestive enzymes action, some work was directed to exploration of the experimental psychology on animals.” That was the initial name for the scientific field which later became widely known as the physiology of HNA.

Thus Pavlov expressed his desire “to assume the power over physiological phenomena”, to spread the power over all aspects of a human body activities – over vegetative, somatic and psychic spheres. Without knowledge of psyche human physiology was an incomplete picture.
Pavlov was unsatisfied with existing interpretation of experimental data; his mind was working hard to find another answer. He complained in 1900: “The problem is that we are still captured by the illusion according to which spirit and body are separate things; in the framework of the natural science such a division is impossible.” Referring to some of his experiments Pavlov concluded: “The facts presented can be conveniently encompassed in the frame of physiological thinking. Our ancient physiological reflex is stable, unconditioned, while a new reflex fluctuates and, as a consequence, is conditioned. In unconditioned reflex we have as an irritating agent those qualities of the object, with which saliva deals in physiological relations… in conditioned reflex it is vice versa: the qualities of the object which normally have no connection with physiological role of saliva, colour, for example, serve as irritating agents. These latter qualities are like signals for former ones. This is finer adjustment of salivary glands to the environment.”
These words express the idea which was often buried under a stream of new facts on the high nervous activity: biological role of the conditioned reflex is to anticipate events, to prepare in advance for reacting to stochastic changes in the environment. From the point of view of a modern cybernetics anticipating (outpost) regulation is the most reliable. Its biological form is temporary connection, conditioned reflex, in particular. Consequently regulatory processes based on conditioned reflex may be regarded as high nervous activity from cybernetic point of view.

“Psychic secretion” of digestive glands was the subject of Pavlov’s most close attention. Being a true experimenter he could not stand any unexplored spots on the “map”, feeling a strong desire to fill them in. So, he decided to uncover the psychic side of digestive glands activity. The decision was followed by 35 years of a purposeful work devoted to special reflexes of the brain which Pavlov called “conditioned reflexes”. History has shown that conditioned reflexes brought to Pavlov more success, fame and glory than his works on physiology of digestion, though it was for the latter that he received the Nobel Prize.
Endeavour to learn about organisation of the brain and about its functions is the most serious challenge to human intellect, as the brain itself is the highest and the most complex of all natural constructions. Though human knowledge about the brain functioning became broader and broader, especially in the 19th century, high divisions of cerebrum cortex and their functions, first of all psychic functions, stayed out of reach of natural science.
The first work on conditioned reflexes was carried out by I. Tolotchinov, a member of the IIEM Department of Physiology, on Pavlov’s suggestion. Under the title “Data on physiology and psychology of salivary glands” it was reported in 1902 at the Congress of doctors and scientists from North Europe which took place in Helsingfors. I.F. Tolotchinov described some of the external conditions of establishing temporary connections in the cortex and discovered the fact of natural reflex formation, the fact of its extinction and restoration, revealed existence of external inhibition of newly formed reflex. His experiments registered specific and observable components of the conditioned reflex, such as movement and salivation.

When he put the question about the mechanism of conditioned reflex (or temporary connection) formation Pavlov in fact put the main question of the brain physiology. As the result a new chapter of the central neural system physiology was created – physiology of the HNA. By 1903 Pavlov and his colleagues had collected enough new facts to deliver a report at XIV International Medical Congress in Madrid. The title of the report read: “Experimental psychology and psychopathology on animals”. In his report Pavlov justified the use of the term “reflex” in investigation of so called “psychic” activity in dogs. He also gave definitions of such notions as “unconditioned” and “conditioned” reflexes. In fact the report comprised the programme of a new scientific area development, devoted to the exploration of normal activities of cerebral hemispheres. It also outlined the perspective of “experimental psychopathology”, that is experimental pathology of HNA. Biological significance of conditioned reflexes in the struggle for existence and their biological expediency, regarding them as an act of adaptation to environment, were especially emphasised in the report.
Theory of conditioned reflexes defined the area of interest for Pavlov, his pupils and colleagues for oncoming decades. By 1906 almost all types of cortical inhibition had been discovered: internal, external, conditioned, sequential, retarding and differentiating. Basics of the conditioned reflex generalisation were laid, and conditioned trace reflexes were discovered. Under Pavlov’s guidance investigations were carried out using extirpation of different areas of cerebral cortex (in dogs) to reveal the link between conditioned salivary reflexes and cerebral cortex.

On May, 7, 1907 Military Medical Academy elected Pavlov as an Academic, on October, 24, 1907 Pavlov became an Academic of the Imperial Petersburg Academy of Science, of its Department of Physics and Mathematics, with specialisation “comparative anatomy and physiology”. He also becomes the Head of the Laboratory of Physiology in the Academy of Science.
The progress of investigations in the field of the HNA demanded a new level of technical equipment for experiments. Pavlov understood the significance of this problem and streamed a lot of energy into developing technical base of his Department in IIEM. As a result the “Tower of Silence”, tree – storey laboratory building with soundproof chambers, was built on the territory of the IIEM.

In 10 years after the first report on conditioned reflexes Pavlov delivered a report “Investigation of HNA” at the final meeting of the IX International Physiological Congress in Groningen (Holland). Such outstanding physiologists as Ch. Sherrington, E. Starling, G. Gemmeter, E. Fisher participated in the work of the Congress. In his report Pavlov substantiated his idea that analysers were special apparatus of the nervous system, and he also presented the perspective of investigation in this direction, based on the idea of unity of the centre and periphery. He also mentioned the possibility of conditioned reflexes being hereditary – the idea, which later transformed into the problem of high cerebral functions inheritance.
During World War I, during two revolutions that followed it and during the Civil War scientific work went on in the Institute. Period of 1918 – 1920 was especially difficult: the country was in ruins, as the result of starvation and cold it was impossible to experiment on dogs. In those years Pavlov paid more attention to studies in psychiatric hospital, which he started in the middle of 1890th with the aim to explore physiological mechanisms of human cerebral cortex activity.

In 1923 Pavlov set the task to “investigate psychotic syndromes and mental diseases”. That is why he could not be content with fractional observations in the hospital and felt a necessity to observe and explore patients systematically. To reach that purpose, in 1931 Pavlov initiated the organisation of two clinics with specialisations in neurology and psychiatry - they served as bases for the Department of Physiology. Each clinic could treat 25 patients. According to Pavlov’s plans investigators focused their attention on neuroses – neurasthenia, hysteria, psychasthenia, as well as on narcolepsy, schizophrenia, maniacal-depressive psychosis. Types of human high nervous activity in connection with different nervous diseases were investigated. Data obtained in clinics were used to analyse pathophysiological mechanisms of the abovementioned diseases, to develop experimental therapy for neuroses and psychoses. From November 1931 till February 1935 Pavlov carried out scientific sessions in the clinics – “clinical Wednesdays”. Materials reported at those meetings were published in 1954 – 1957. “Wednesdays” were known for their atmosphere of free discussion. At the meetings participants analysed clinical observations and medical histories from the physiological point of view. However, Pavlov called for care in introduction into practical medicine of the results gained in experiments on animals.
In 1919 – 1920 the situation in Petrograd (St. Petersburg) was very difficult. In March of 1919 the Council of State Institute for Experimental Medicine (former IIEM) was informed that Pavlov was seriously ill as the result of “lack of firewood and heating”. But it was not only cold, starvation and household difficulties. The time was shadowed with frisks and arrests which took place all over the city and did not miss many of Pavlov’s colleagues from the Institute. It was not the best atmosphere for scientific work, and Pavlov applied to Narcompross (the organisation with the functions that are usually fulfilled by the Ministry of Education) and to Sovnarcom (the Government) of the Russian Federation for permission to go to Sweden with his family by the invitation of the Swiss Red Cross. It coincided with the governmental decision to provide Russian leading scientists with conditions more comfortable for their work. Pavlov was included in that elite group. But he refused an assigned rich food ration and asked for conditions in his laboratories to be made enough comfortable for scientific work. Apparently he was satisfied with the fact that the Government recognized the importance of his studies as they ensured material and technical basis for his work, so he never again applied for permission to leave the country.

In 1921 – 1923 scientific work in the Department of Physiology gradually came to normal, investigations were renewed. In his report “Normal activity and general constitution of cerebral cortex” delivered in 1922 at the meeting of the Society of Finnish Doctors in Helsingfors Pavlov distinguished 6 types of events which “embraced the whole HNA without residue”. He included in those 6 types the excitation, inhibition, movement (irradiation and concentration), mutual induction, connecting and disconnecting, and, finally, analysis. It was a report which summarized the most important results of his two-decade work. In 1923 Pavlov’s book “Twenty Years Experience in Objective Study of Higher Nervous Activity (Behaviour) of Animals” was published. It comprised his articles, reports, lectures and speeches presented in chronological order, so that it reflected the course of development of the theory of conditioned reflexes. Emphasising special significance of the sixth edition (the last one published during his lifetime) of the “Twenty Years Experience” Pavlov wrote in January of 1936 that the book was enriched “abundantly” – 12 new works were added to it. According to Pavlov those works clearly demonstrated “how immensely the horizon of research has extended… Physiology, pathology with therapy of cortex of the brain and psychology with its practical applications start to join, to merge, so that they become the same field of scientific work, and, judging by the results, to their mutual benefit.”
In 1925 – 1927 much attention was paid to investigation of nervous system types, to studying different kinds of internal inhibition and their mutual induction. In 1927 Pavlov’s book “Lectures on the Work of Large Hemispheres of the Brain” was published. In the same year he suggested that nervous system types would be studied on dogs, and while researching other problems the type should be taken into consideration.
Most generally the results of researches in Pavlov's laboratories were concerned with systematic investigations of experimental neuroses, development of the conception of nervous system types, a problem of coordination in brain hemispheres functioning, genetics of the HNA, study of the nervous mechanism of normal and hypnotic sleep. The extensive experimental material became a basis of the new point of view on reflexes. All reactions of an organism were referred to the latter group without exception, if they were caused by excitation of the nervous terminals and carried out with the participation of nervous system. The conception of the conditioned reflexes, giving the possibility to explain the mechanism of connections of an organism with an environment formation, became a starting point of organism functions study in their dependence on activity of cerebral cortex under various life conditions. The problem of neuroses dramatically facing the clinics became a subject of investigation and, undoubtedly, has influenced the direction of HNA fundamental studies, and also the development of evolutionary-genetic researches.
Studies of anthropoids’ behavior were highly important for the development of the investigations of HNA physiology. In particular, significant development of orienting-research activity in apes was established, for example, the ability of chimpanzee to form the long sequences of motional conditioned reflexes for realization of problem tasks was revealed, etc. In connection with results of these researches Pavlov offered the conception on classification of temporal connections to conditioned, sensor and signal. The latter was contemplated to be anthropoid’s ability to establish the causal-consequential relations between subjects and the phenomena. He also expressed the opinion on impossibility of highly developed animal's behavior treatment only on the basis of the conditioned reflex mechanism.

Expansion of a research sphere in physiology of animal HNA has led Pavlov to create in 1924 of Biological station near village Koltushi under the aegis of Department of Physiology, being the subdivision of IIEM up to 1939.
It is necessary to note, that in 1925, being retired from MMA, Pavlov has headed the Institute of Physiology of USSR Academy of Science organized under his initiative on the basis of Physiological Laboratory of the USSR Academy of Science, over which he had supervised being the academician from 1907. The staff of this laboratory included only of 2 employees. Organization of Institute of Physiology on 5.12.1925, for the furnishing and staff expansion of which the USSR Academy of Science has marked significant funding, has allowed Pavlov to essentially expand a spectrum of scientific work. All researches which were carried out in the Department of physiology IIEM and in Institute of Physiology of the USSR Academy of Science were conceptually indivisibly interconnected and developed in a framework of creative plans of their head.
Pavlov by virtue of his scientific biography characterized by exclusive bias for a determinism and a nervism, and also due to interest to a nature of human mentality, appeared in him in his youth, under I.M. Sechenov's influence, speculated within the framework of the scientific ideology essentially differed from behaviorism. He, naturally, has wended his way to search for brain mechanisms providing adaptation of an organism to an environment. In a Pavlov's terminology these are the mechanisms of forming of a conditioned reflex or of temporal connection. This approach to investigation of brain functioning has allowed him to solve the problem of how the brain works, organizing and controlling the interaction of an organism with world around, what nervous mechanisms provide this activity of it, which shortly can be designated as training.

The question on the mechanism of training has stated before Pavlov from the very beginning of his work with conditioned reflexes. The first attempt of physiological interpretation of nervous mechanisms of conditioned reflex formation was made by him in already mentioned Madrid speech in 1903. He has presented these mechanisms as "attraction" of excitation from accidental receptors activation (subsequently named "indifferent excitation, a signal") to the salivary gland center.
What is the importance of this experimental - theoretical conception? Solving the problem of mechanisms of conditioned reflex links formation to the extent, corresponding to the theoretical and experimental opportunities of his time, Pavlov and his school transferred brain mechanisms of training in the spatial (material) form, what was never made by the psychologists, who had the non-spatial mentality, a nature of consciousness and reason in the form of accumulation of subjective experience resulting from training (thinking) as the subject. In other words, Pavlov with his physiological approach to studying of mental activity has returned a science investigating the brain functioning, on firm ground of materialism.
As a result a new chapter of central nervous system physiology of the - physiology of the HNA was created, which subject was presented by Pavlov in his speech on general meeting of the Society of the Moscow scientific institute on 24.03.1913. In this speech he again has addressed to the term "mechanism", speaking about the mechanism of temporal connections - a conditioned reflex, about mechanisms of analyzers (sense organs), about the nervous mechanism of a subjective phenomenon of affect, about the internal mechanism of nervous activity of a dog etc.
The main feature of the functional organization of the developed nervous system is the dynamism of connections of cells forming it, without what it might not carry out its peculiar functions: to connect all systems of the organism providing perception of the external and internal environment, and also its own condition, the consulting of the former experience of interaction with environment, an estimation of the current needs and formation of proper responses and behavior in certain conditions, in integral continuous activity. All this demands especially flexible, plastic and at the same time steady functional (working) connections between nervous cells. Elucidation of these connections mechanisms is the main problem, and it is possible to tell, the subject of modern neuroscience.
Great scientific and scientific - organizational work of Pavlov in IIEM cannot be separated from his extensive activity covering problems of development of a domestic science, perfection of preparation and education of highly skilled physicians, and various aspects of public life of Russia also.

His attitude to February revolution in Russia Pavlov has publicly promulgated earlier, speaking on 28.03.1917 in Petrograd Medical Institute for Women at the organizational assembly of a society "Open association for development and diffusion of positive sciences". "Russia is experiencing now the quivering period of liberating, the period of free hands: make from yourself anything you want and anything you can, - has declared Pavlov in his speech, - but now, all of us urgently need to be infiltrated by dispassionate consciousness, that after has descended on - and so easily - completely rotted building of the old state system, all of us bear overwhelming by its grandness, even frightening task - to found correct basis of a new building of fair, happy and strong Russia".
Several years after Pavlov have tried to apply the theory of conditioned reflexes to an explanation of e public life events. In 1924 he has come out with public lecture "Several applications of new brain physiology to life". Referring to observations of a dog in which only long hunger period has suppressed a so-called reflex of freedom, Pavlov has declared, that dictatorship of proletariat is accompanied by terror and it may result in tragic consequences: "Terror, moreover accompanied by famine, completely suppresses a reflex of freedom, the nation will be bullied, decried as slaves".
However a culmination of Pavlov's civic courage became his letter to the USSR Sovnarcom (Government), written three weeks after Sergey Kirov's murder, on 21.12.1934. Explaining the reasons which have induced him to remain in Russia and his attitude to "world revolution" in it, Pavlov wrote :"We lived and we live under an indefatigable regime of terror and violence. If our common being would be reproduced entirely without exception, with all daily details, there would be the horrifying picture, the tremendous impression from which for normal people hardly probable would be considerably attenuated, if we would put near to it other our picture with wonderfully growing cities, Dneprostroys, giant factories, countless scientific and educational institutions. When the first picture fills my attention, most of all I see similarities of our life to life of ancient Asian despotism. And we refer to it as republics. How it can be understood? Maybe, it is provisionally. But it is necessary to remember, that to the person who was developed from an animal, it is easy to fall, but it is difficult to rise. It is hardly possible to remain the beings feeling and thinking humanly for both, those who spitefully sentence to death masses of people and with satisfaction put it into effect, as well as for those, who are violently habituated to participate in it. On the other hand, it is hardly possible to become beings with feeling of human self-respect for those who are transformed into bullied animals. When I see new cases from a negative zone of our life (it is a legion of them), I am tormented with a poisonous reproach that I stayed and stay among it. Not only I think and feel so? Spare the native land and us".

During the XV International physiological congress which was taking place in Leningrad and in Moscow in 1935, on which Pavlov was proclaimed as "father of physiologists of the world" and the Biological station in Koltushi has got the world popularity as the "capital of conditioned reflexes".
Pavlov died on 27.02.1936. Last time he visited the Department of physiology of IEM on February 18, which is certified by the sheet of a desk calendar on his desk in the study which is the memorial now. By the decision of the Government his name was given to the Department of Physiology of IEM headed by him, to 1-st Leningrad Medical Institute (nowadays the St.-Petersburg State Medical University named after. I.P. Pavlov), to Physiological Institute of the USSR Sci Academy (nowadays Institute of Physiology named after I.P. Pavlov of the Russian Sci Academy), and also to many other research and educational medical institutions.