Carl Baer contribution to biology. Presentation for a lesson in biology on the topic: Biographies of scientists biologists. Carl Ernst von Baer

(1792-1876) Russian naturalist, founder of embryology

Karl Maximovich Baer was born on February 28, 1792 in the town of Pipa, Estonian province, in a poor, large family of a retired lieutenant. The boy received his primary education at home, after which he studied at high school in Reval (Tallinn), after graduating from which he entered the medical faculty of the University in Derit (Tartu). Student years Karl Baer coincided with the Patriotic War of 1812.

The young man, seized with a patriotic impulse, took part in it as a medical volunteer. In 1814 he graduated from the university with the title of doctor of medicine, having defended a dissertation on the topic of diseases common in Estonia. Considering university education insufficient for independent medical practice, Karl Baer went to Vienna, and then to Germany in order to acquire practical medical knowledge.

In 1817 he was invited to work in Koenigsberg, to Professor KF Burdakh, and in 1819 he became a professor of zoology at the University of Koenigsberg. It was here in 1819-1830. Karl Maksimovich Baer conducts his work on embryology, which has earned him worldwide fame. He begins by studying the development of the chick embryo. In less than 4 years, the scientist examined more than two thousand embryos, spreading them in water with thin needles and examining them under a magnifying glass and microscope. Later, the embryos of crustaceans, insects, and mammals are studied in the same way.

The works of Karl Baer are rich in new discoveries. Among them, first of all, is the discovery of the egg in mammals, in particular in humans, the discovery of the dorsal string in vertebrates. In addition, it was he who managed in his research to expand knowledge about the formation of germ layers in the process individual development animals.

Of particular interest in biology is the so-called law of germline similarity formulated by Baer. The essence of this law is as follows. In the early phase of development, the embryos of all vertebrates, regardless of their belonging to one class or another, are so similar to each other that it is difficult to distinguish them from each other. Later, in a certain sequence, the embryos begin to show signs of a class, order, family, and genus. Species specificity appears only at the end of embryogenesis. These conclusions, based on rich experimental material, convincingly refuted the prevailing early XIX centuries, the position that the embryos of higher animals go through stages in their development corresponding to the adult forms of lower organisms.

The law of germline similarity was adopted by Charles Darwin when substantiating the theory of evolution.

In 1834, Karl Maksimovich Baer returned to Russia, to St. Petersburg. With the move, the young academician's scientific interests and lifestyle. In a new place, he is attracted by the boundless expanses of Russia. Huge, but little explored Russia of that time required a comprehensive study. And the biologist becomes a geographer-traveler and explorer of the natural resources of the country. He leads expeditions to New Earth, islands of the Gulf of Finland, Kola Peninsula, Volga region. He studies geography, flora and fauna of the Black, Azov, Caspian Seas.

Investigating the patterns of formation of river valleys, the scientist found that the rivers flowing along the meridian always have a steeper western bank due to the fact that it is washed away by the current, which deviates under the influence of the Earth's rotation. This position is known in geography as Baer's law. Karl Baer was one of the initiators and founders of the Russian geographical society, which still exists and in which he was chosen as the first vice president.

Since the beginning of the 50s, Karl Maksimovich Baer has been fond of ethnography and anthropology, especially craniology (the study of the skull). By applying improved methods for measuring skulls, which made it possible to objectively compare the craniological features of people different races, the scientist came to important, fundamental conclusions about the nature of racial differences. His main conclusion was the assertion of the unity of origin of all human races, undoubtedly belonging to the same species. The existing racial characteristics - the color of the skin and hair, the difference in facial features and the shape of the skull, in his opinion, are of little importance and do not give grounds for dividing the human race into different species.

In 1864, the St. Petersburg Academy of Sciences, celebrating the 50th anniversary of the scientific activity of the scientist, presented him with a large medal and established Baer Prizes for outstanding achievements in the field. natural sciences. Its first laureates were the young Russian embryologists A. O. Kovalevsky and I. I. Mechnikov, the brilliant creators of comparative evolutionary embryology.

A cape on Novaya Zemlya, an island in the Taimyr Bay, a range of hills in the Caspian lowland (Baer hillocks) are named after Karl Maksimovich Baer.

The largest biologist of the first half of the 19th century, the founder of modern embryology. The great-grandson's name is Max von Lingen. He was in our city last year and participated in a seminar held by the BAN, dedicated to the memory of his great great-great-grandfather.

Carl Ernst von Baer
Karl Ernst von Baer

Karl Maximovich Baer (1792-1876) - an outstanding natural scientist, according to V.I. Vernadsky, is among the greatest minds of mankind. Throughout the world, Karl Baer is considered practically the founder of embryology - as a science. He also owns the discovery of a geographical phenomenon in the Caspian lowland, which I now call the Baer Hills. Bera Island is located in the Laptev Sea. Karl Baer was the first to establish the existence of such a phenomenon as permafrost. Entomologist and anthropologist. A researcher of the works of Homer, who proved in practice that the journey of Odysseus actually took place and passed from Ithaca to the eastern shores of the Black Sea. Historian who wrote a work about the polar expeditions of Peter the Great. Anthropologist. Entomologist. Zoologist. Botanist. Ichthyologist. Anatomist. Doctor. Darwinist before the advent of Darwin's writings. Poet. Polar explorer. One of the founders of the Russian Geographical Society.
How did it happen that the interests and, most importantly, the successes of one scientist are so diverse?

Let's start the story about him with a multiple reference about what Embryology is, to the creators of which Baer is considered.

Embryology(from Ancient Greek ἔμβρυον, germ, "embryo"; and -λογία, -logy) is a science that studies the development of the embryo. interesting History of embryology. Embryological research in India, China, Egypt and Greece up to the 5th c. BC e. largely reflected religious and philosophical teachings. However, the views that developed at that time had a certain influence on the subsequent development of E., the founders of which should be considered Hippocrates (as well as the authors of the so-called Hippocratic Miscellany adjoining him) and Aristotle. Hippocrates and his followers most attention devoted to the study of the development of the human embryo, recommending only for comparison to study the formation of a chicken in an egg. Aristotle made extensive use of observations, and in the writings “History of Animals” and “On the Origin of Animals” that have come down to us, he reported data on the development of humans, mammals, birds, reptiles and fish, as well as many invertebrates. Aristotle studied the development of the chicken embryo in most detail. The embryological views of Aristotle persisted throughout the Middle Ages until the 16th century. without significant changes. An important stage in the development of E. was the publication of the works of the Dutch scientist V. Keuter (1573) and the Italian scientist Fabricius of Aquapendente (1604), which contain new observations on the development of the chicken embryo. A significant shift in the development of ecology began only in the middle of the 17th century, when W. Harvey's work Studies on the Origin of Animals (1651) appeared, the material for which was the study of the development of the chicken and mammals. Harvey generalized ideas about the egg as the source of development of all animals, however, like Aristotle, he believed that the development of vertebrates occurs mainly through epigenesis, argued that not a single part of the future fetus "does exist in the egg actually, but all parts are potentially in it »; however, for insects, he assumed that their body arises through the “metamorphosis” of initially preceding parts. Harvey did not see the eggs of mammals, just like the Dutch scientist R. de Graaf (1672), who mistook ovarian follicles for eggs, which later became known as Graaffian vesicles. The Italian scientist M. Malpighi (1672) used a microscope to discover organs at those stages of chicken development at which it was not possible to see the formed parts of the embryo before. Malpighi joined the preformist ideas , dominant in embryology almost until the end of the 18th century; Their main defenders were the Swiss scientists A. Galler and C. Bonnet. The decisive blow to the concept of preformation, which is inextricably linked with the idea of the immutability of living beings, was dealt by K. F. Wolf in his dissertation Theory of Origin (1759, published in Russian in 1950). In Russia, the influence of Wolf's ideas was reflected in the embryological studies of L. Tredern, H. I. Pander, and K. M. Baer.

The founder of modern E. K. M. Baer discovered and described in 1827 an egg in the ovary of mammals and humans. In the classic work On the History of Animal Development, Baer was the first to describe in detail the main features of the embryogenesis of a number of vertebrates. He developed the concept of germ layers as the main embryonic organs and clarified their subsequent fate. Comparative observations on the embryonic development of birds, mammals, reptiles, amphibians and fish led Baer to theoretical conclusions, the most important of which is the law of similarity of embryos belonging to different classes of vertebrates; this similarity is all the more the younger the embryo. Baer connected this fact with the fact that in the embryo, as it develops, the properties of type appear first of all, then class, order, etc.; specific and individual features appear last.

Karl Baer, in his writings on embryology, formulated patterns that were later called "Baer's Laws":

the most common characters of any large group of animals appear in the embryo earlier than the less common characters;
after the formation of the most general signs, less common ones appear, and so on until the appearance of special signs characteristic of this group;
the embryo of any kind of animal, as it develops, becomes less and less like the embryos of other species and does not pass through the later stages of their development;
the embryo of a highly organized species may resemble the embryo of a more primitive species, but never resembles the adult form of that species.

In the book “On the history of animal development. Observations and Reflections”, published in Koenigsberg in 1837, Karl Baer came to the conclusion that “the history of nature is only the history of the continuing victory of the spirit over matter... it makes individuals and series of beings disappear from the face of the Earth and rebuilds modernity on the ruins of an exorbitant past.”

Karl Ernst, or, as he was called in Russia, Karl Maksimovich Baer, was born on February 17 (28), 1792 in the town of Pip, in the Gerven district of the Estland province. Baer's father, Magnus von Baer, belonged to the Estonian nobility and was married to his cousin Julia von Baer.

Little Carl early began to be interested in various objects of nature and often brought home various fossils, snails and the like. As a seven-year-old boy, Baer not only could not read yet, but did not know a single letter. Subsequently, he was very pleased that "he did not belong to the number of those phenomenal children who, due to the ambition of their parents, are deprived of a bright childhood."
In 1810 he entered the Dorpat (Tartu) University, from which he graduated in 1814. Baer passed the exam for a doctorate in medicine. He presented and defended his thesis "On endemic diseases in Estonia" (Dissertatio inaugurales medica de morbis inter esthonos endemicis. Auctor Carolus Ernestus Baer. Dorpat, litteris Schummanni. 1814. 88 c.).

In the bowels of the Internet, I found some interesting information about Estonians, allegedly taken from the materials of this dissertation:

« All of them, to the last, are serfs of the Germans - they are poor and boring in the use of many things ... Estonians are very greedy. Already herself northern country makes it easy to guess; however, they far surpass their neighbors at the same geographical latitude in this. Hence the reasons for the fact that from childhood they stuff the stomach unnecessarily and stretch it ... This people also strives for a more joyful mood, in order to forget for a moment the oppressive conditions of life, although their rough soul finds consolation only in wild and violent fun, and calm cheerfulness is alien to it ... As for spiritual culture, most European peoples surpass them significantly, for very few Estonians have learned to write ... Of the shortcomings, which cannot be denied in any way, I would list them: laziness, uncleanliness, excessive subservience to the strong and cruelty, savagery towards the weaker ones ... "

However, Estonians in Tartu 10 years after the death of Baer on November 16, 1886, a monument to the great scientist was erected with public money (sculptor Opekushin).

And on the 2-kroon Estonian banknote, the Estonians also depicted a portrait of Baer.

After graduating from Dorpat University, Baer went abroad, choosing to continue his medical education Vienna, where such famous people of the time as Hildebrand, Rust, Beer and others taught. In the autumn of 1815, Baer arrived in Würzburg to another well-known scientist, Dellinger, to whom he handed, instead of a letter of recommendation, a bag of mosses, explaining his desire to study comparative anatomy. The very next day, Karl, under the guidance of an old scientist, set about dissecting a leech from a pharmacy. In this way, he independently studied the structure of various animals. All his life, Baer kept the liveliest gratitude to Dellinger, who spared neither time nor labor for his education. Since then, Baer's teaching and scientific activities have entered their permanent track. He led the practical classes of students in the anatomical theater, taught courses in human anatomy and anthropology, and found time to prepare and publish special independent works.

In 1819, he became an extraordinary professor of zoology at the University of Königsberg with an assignment to take up the organization of the zoological museum at the university. In general, this year was a happy one in Baer's life: he married one of the residents of Koenigsberg, Augusta von Medem. Gradually, in Königsberg, Baer became one of the prominent and beloved members of the intelligentsia - not only among professors, but also in many families that had no direct relationship to the university.

Excellent command of German literary language, Baer sometimes wrote German poetry, moreover, very good and smooth. “I must repent,” Baer says in his autobiography, “that one day it really occurred to me that there was a poet in me. But my attempts made it clear to me that Apollo was not sitting by my cradle. If I did not write humorous poems, then the ridiculous element nevertheless involuntarily crept in in the form of empty pathos or a tearing elegy.

In the autumn of 1829 Baer went to Russia. But after a short stay in St. Petersburg, which made an unfavorable impression on him, the scientist again settled in Königsberg, to the great joy of his family and friends. His situation continued to improve: the government allocated funds for the construction of a new building for the zoological museum, in which Baer was given an apartment.

Baer continued his scientific studies with extraordinary zeal. He sat at the microscope for days on end and, in the end, greatly upset his naturally strong health. While Baer was thinking about how he could change his position, an unforeseen event led to a new turn in his career. The elder brother Ludwig fell ill and died; the family estate in Estland he managed was burdened with debts and required good management, which could not be expected from anyone else except from Karl. Thus, Baer had to go back to Estonia.

He decides to send a request to the St. Petersburg Academy of Sciences: will there be a free place for him in it? The Academy responded by electing Baer again as a member, and thus the final resettlement of Baer to Russia was decided. At the end of 1834, Baer was already living in St. Petersburg.

From the capital, in the summer of 1837, the scientist traveled to Novaya Zemlya, where no naturalist had ever been before. Baer was delighted with the abundance and novelty of the impressions made on him by this poor and brutally harsh country.

This journey entailed the desire for new similar enterprises. In 1839, Baer made a trip with his eldest son Karl to explore the islands of the Gulf of Finland, and in 1840, together with the future famous traveler Middendorf, he visited the Kola Peninsula. Thus, Baer became more and more involved in the study of geography, and from 1840 he began to publish, together with Gelmersen, a special journal at the academy, called Materials for the Knowledge of the Russian Empire.

His travels, however, were interrupted for a time by the new duties assigned to him. Since 1841, the scientist was appointed ordinary professor of comparative anatomy and physiology at the Medico-Surgical Academy. But the position of professor, although it significantly increased the content, so burdened him, leaving at the same time no convenience for independent zoological work, that Baer resigned this title in 1852.

In 1851, Baer submitted to the Academy of Sciences a large article "On Man", intended for Semashko's "Russian Fauna" and translated into Russian.

Since 1851, a series of Baer's travels began in different places Russia, undertaken for practical purposes and involving Baer, in addition to geographical and ethnographic research, in the field of applied zoology. He led expeditions to Lake Peipsi and the shores of the Baltic Sea, the Volga and the Caspian Sea. His "Caspian studies" in eight parts are very rich in scientific results. In this work of Baer, the eighth part is most interesting - “ On the universal law of the formation of river channels». It's about about a remarkable phenomenon, which later received the name of Baer's law, under this name it entered the textbooks of geography. Baer, during his many travels, could not fail to notice that the right bank of Russian rivers (if you look in the direction of the river) is usually high, and the left is low. Thinking about the cause of this phenomenon, he came to the following theory. If a flowing water is directed approximately parallel to the meridian, from the equator to the pole, then due to rotation the globe from west to east, the water, bringing with it a greater speed of rotation than in the northern latitudes, will press with particular force on the eastern, that is, the right bank, which therefore will be steeper and higher than the left.

K.M. Baer is also known as one of the greatest anthropologists of his time, as an organizer of anthropological and ethnographic research in Russia. Of particular interest is his work "On the Origin and Distribution of Human Tribes" (1822), which develops a view of the origin of mankind from a common root, that the differences between human races developed after their settlement from a common center, under the influence of various natural conditions in their habitats. Perhaps, this work for the first time is not just a collection of anthropological information, and is not reduced to a simple postulation of some idea, but is an attempt at a demonstrative logical conclusion of a certain hypothesis. In 1824 K.M. Baer published his lectures on anthropology. Of the three parts conceived by the author, only the first was printed - an anthropography, outlining the basics of human anatomy and physiology. The other two parts were to be devoted to the comparison of man with animals, his position in the system of the animal world, as well as a description of the differences within mankind, the question of subdivisions within the species, the influence of climatic factors and living conditions on the structure of man. Unfortunately, the completed work never saw the light of day. Partially his ideas K.M. Baer outlined in a number of popular articles published in the 50-60s. In Petersburg.
Since 1842 K.M. Baer heads the Anatomical Cabinet of the Academy of Sciences in St. Petersburg, where a small craniological collection, the famous Petrovsky collection of freaks and anatomical preparations purchased by Peter I from the Dutch anatomist Ruysch. Thanks to Baer, this cabinet becomes the basis of a future major museum. Baer supervised it and devoted a lot of energy to replenishing and systematizing, first of all, his craniological collections. In the process of studying them, Baer published a number of articles on craniology. The first of them refers to 1844 and is devoted to the description of the Karagas skull, which he compares with the Samoyed and Buryat skulls. This is not only the first craniological work in Russia, but, undoubtedly, one of the first craniological studies, in which many methodological and general issues anthropology.
By 1859, an article by K.M. Baer "On the Papuans and Alfurs", which details his views on the origin of the human races. He also owns special works - about deformed skulls, about the craniological type of the Slavs and a number of others. K.M. Baer was the founder of the study of the anthropological type of the Kurgan Slavic population of Russia and a direct predecessor of the outstanding works of A.P. Bogdanov in this area.
Special mention should be made of Baer's merits in the development programs and methods of anthropological, primarily craniological research. Already in the works of the 40s and 50s, he points to the need to develop uniform principles for measuring the human body (primarily the skull). K.M. Baer was the initiator of the Congress of Anthropologists, which took place in Göttingen in 1861. The methodology and program of craniological research proposed by him at the congress formed the basis for further work. craniologists both in Russia and abroad.
From theoretical problems anthropology, K.M. Baer was attracted by questions of the origin of human races, factors in the emergence of racial characteristics. The main position that he developed in his works is that differences, both in the physical type and in the culture of peoples, are due to the peculiarities of the geographical environment, the influence of climate and terrain (the tradition of J.B. Lamarck). He consistently develops the hypothesis of a single origin of mankind and its settlement from a single center (the theory monocentrism). These views stemmed from the recognition of the variability of forms in the animal kingdom and the common origin of related species. Throughout his activities, K.M. Baer held the theory transformism.

In 1835 K.M. Baer, in addition to his main activity at the Academy, showed a desire to engage in the Library. He was appointed director of the Foreign Department of the academic library and remained in this post until his retirement in 1862.

The largest measure to improve the organization of book collections and catalogs was the creation of a new scientific library classification, thanks to which library collections began to be formed and arranged in accordance with the level of development of the exact natural sciences and humanities. In accordance with this scheme, all foreign books and magazines were encrypted and distributed until 1929. Currently, this fund is part of the main foreign fund of the BAN and is called the Baer Fund, being an active, actively used book collection.

Baer made a huge contribution to the solution practical tasks on the study and rationalization of fisheries on Lake Peipus, on the Caspian and Azov Seas. For 4 years (1853-1856) he spent expeditions on the Caspian Sea. The predatory fishing by private industrialists in the mouth of the Volga and in the Caspian Sea, the main region of fish production of then Russia, led, as today, to a catastrophic drop in the catch of fish and threatened with the loss of this main fishing base. In order to accomplish the task, Baer decided to conduct a preliminary detailed study of the hydrological and hydrobiological features of the Caspian Sea, which had not been studied at all before him. Wherein. he furrowed the Caspian in several directions from Astrakhan to the coast of Persia. He established that the reason for the decline in the catch was not at all the impoverishment of nature, but the acquisitive and selfish interests of private fishermen, the predatory methods of fishing and the irrational primitive methods of processing it, which he called "the insane waste of the gifts of nature." It is impossible to catch fish before spawning and during it, it is impossible not to engage in the reproduction of fish by artificial methods: nature is not a bottomless barrel. Baer demanded the introduction of state control over the protection of fish stocks and their restoration.

A unique edition was discovered in the depths of the Internet: Baer, Karl Maksimovich "Drawings for the study of the Caspian fishery". Published by the Ministry of State Property. St. Petersburg, in the printing house of V. Bezobrazov, 1861. Numerous color and tone lithographs, in addition to scientific, also have artistic significance. Rarity!

Although Baer enjoyed general respect and had no shortage of friendly society, he did not particularly like life in Petersburg. Therefore, he was looking for opportunities to leave Petersburg and go somewhere to live out the rest of his life in peace, devoting himself exclusively to his scientific inclinations, without any official duties. In 1862 he retired and was elected an honorary member of the academy.

On August 18, 1864, a solemn celebration of his anniversary took place at the St. Petersburg Academy of Sciences. The emperor granted the hero of the day a lifetime annual pension of 3,000 rubles, and the Baer Prize was established at the Academy of Sciences for outstanding research in the natural sciences.

Baer was very witty, and his well-aimed, merrily mild humor shone through both in his speeches and in his writings, sometimes even in articles of a special nature. For an example of this humor, it is not out of place to quote the following excerpt from his speech, said in response to Middendorf's greeting during the celebration of the fiftieth anniversary of Baer's scientific activity:

"In closing," Baer said, "let me once again thank everyone here for their participation and try to repay them for it." new theory. Death, as everyone knows, has been proven by experience, and this experience has been repeated very often, but the necessity of death has still not been proven in the least. The lower organisms often live only for one particular season of the year, and their life does not extend beyond these limits, unless they leave behind the germs of new individuals; such are, for example, annual plants. But for organisms that survive winter and summer and have the means to accumulate food materials, that these organisms must necessarily die, I repeat, this has not been proven. The famous Harvey once dissected a man who died at the age of 152, and found all his organs perfectly healthy, so that this man probably could have lived even longer if he had not been moved from the village, for the sake of better care behind him, to the capital, where he died from too good care. I am therefore inclined to regard death as a mere manifestation of imitation, as something like a fashion, and a fashion completely unnecessary. In this conviction, I am strengthened by the philosophy of Schopenhauer, which considers everything that exists as a manifestation of the will. If a stone falls, it is only the effect of its inherent will, which causes it to fall, just as I walk as a result of my will, which makes me walk. And so I set myself the task of not wanting death, and if my organs do not want to fulfill their duties, then I will oppose my will to their will, to which they will have to obey. I advise everyone present to do the same and invite you all to my second doctoral jubilee in 50 years at the same place, and I only ask you to do me the honor of allowing me to accept you as guests, as a host.

These words, coming from the mouth of a 72-year-old man, amaze as much with their witty humor as with their cheerfulness, which can rarely be found in young man. They eloquently testify to the fullness of spiritual strength and clarity of mind, characteristic of Baer even in his advanced years!

Karl Baer belonged to those scientists whose inspiration makes science related to poetry.

After the anniversary, Baer considered his St. Petersburg career finally completed and decided to move to Dorpat, since, having gone abroad, he would have been too far from his children. Baer's family by this time was greatly reduced: only daughter his Maria married Dr. von Lingen in 1850, and of his six sons only three survived; Baer's wife died in the spring of 1864. In the early summer of 1867 he moved to his native university town.

The elderly scientist continued to be interested in science here, at rest. He prepared his unpublished works for publication and, as far as possible, followed the progress of knowledge. His mind was still as clear and active, but his physical forces began to betray him more and more. On November 16 (28), 1876, Baer died quietly, as if he had fallen asleep.

Naturalist. Born in Estonia. In 1810 he entered the medical faculty of Dorpat University, after which he defended his doctoral dissertation “On endemic diseases in Estonia” (original in Latin). After that, K. M. Baer left for Austria, and then to Germany. From 1817 he was the prosector of the University of Königsberg, from 1819 he was a professor of zoology, and from 1826 he was a professor of anatomy and head of the anatomical institute and the zoological museum of the same university. In 1826, Baer was elected a corresponding member, and in 1828, an ordinary member of the St. Petersburg Academy of Sciences. In 1830-34. was an honorary member of the Academy. In 1834, upon his return to Russia, K. M. Baer was again elected an ordinary academician. Since 1862, K. M. Baer is an honorary member of the St. Petersburg Academy of Sciences with the right to attend meetings of the Academy and with the right to vote on them. Working at the University of Koenigsberg (1817-34), K.M. Baer taught a practical course in comparative anatomy of invertebrates, taught courses in human anatomy and anthropology. Of the comparative anatomical studies of Baer of this period, it should be noted the work on the anatomy of the sturgeon, dolphin, elk, camel and various invertebrates. K. M. Baer studied L. Oken's "Naturphilosophy" and saw in it only "vague uncertainty." Baer's studies of the embryonic development of animals are best known. Interest in these works arose from K. M. Baer as early as 1818, when he received from his friend X. I. Pander his dissertation "Materials for the history of the development of a chicken in an egg." In 1827, Karl Maksimovich discovered the egg of mammals and humans, correcting the misconception that the entire ovarian vesicle is an egg. The work "On the Origin of the Egg of Mammals and Man" (1827) Baer published in the form of a message to the St. Petersburg Academy of Sciences.

Baer is the founder of embryology. His classic work On the History of the Development of Animals (1828-37) is replete with a great deal of factual material, comments and generalizations. K. M. Baer discovered the dorsal string (primary internal skeleton of vertebrates), traced the development of fetal membranes, described the formation of the brain from bubbles, as well as the development of the eye, heart and other organs. He showed the presence of an early stage of embryonic development in the form of a blastula. In addition to a detailed study of the development of the chicken, he studied the embryonic development of reptiles, amphibians, fish and mammals. Comparative embryological studies on vertebrates led K.M. Baer to important theoretical generalizations. He established that in the process of embryonic development, the most general signs first appear, in particular, the type to which the animal under study belongs, then the signs of a class, order, family, genus, species, and, finally, individual signs of an individual are sequentially isolated.

The facts discovered by Karl Maksimovich were of great importance in the fight against preformism - the doctrine that prevailed in the 17-18 centuries, about the transformation of organisms in the germ cells of parents. Recognition of the process of evolution for Baer was, as he himself put it, "a postulate of reason." In interpreting the process of evolution of living nature, Baer will tend to the idealistic theory of autogenesis: driving forces evolution, he considered some special "internal causes". Rejecting the theory of the constancy of species, he also objected to evolutionary theory Darwin, especially against the theory of natural selection.

Having moved to Russia (1834), KM Baer participated in several expeditions: in 1837 he was on Novaya Zemlya, in 1839 he visited the islands of the Gulf of Finland, in 1840 he traveled around Lapland. very important practical value had his expeditions to study and rationalize fishing on Lake Peipus, on the Caspian and Azov Seas. direct economic importance These expeditions were expressed, in particular, in the proposal to eat Caspian herring, which was previously caught only for rendering fat. The scientific results of the Baer expedition were a thorough geographical description of the Caspian Sea, a special series of publications on the graphic arts of Russia, etc. He expressed (1857) a position on the erosion of the right banks of rivers in the northern hemisphere and the left ones in the southern ("Baer's law"). KM Baer is one of the founders of the Russian Geographical Society. He also developed issues of anthropology, was a supporter of the recognition of the species unity of the human race and an opponent of polygenists.

As a professor at the Medico-Surgical Academy (1841-52), he pointed to the low scientific level of foreign doctors - teachers of the academy, tirelessly advocated the training of Russian specialists.

In 1862, K. M. Baer left Petersburg Academy Sciences and soon moved to Dorpat (Tartu), where he died. In honor of Baer, on the anniversary of the 50th anniversary of his scientific activity, a bronze medal was knocked out, and the Academy of Sciences established a prize named after. Baer (1864).

The following are named after Baer: the mountains of Baera (Taimyr, the coast of Kh. Laptev), the island of Baera (Taimyr Bay), Cape Baera (Novaya Zemlya).

K. M. Baer is an academician, one of the most remarkable naturalists of the 19th century. And the versatility of Baer's interests and the fame of his work in various areas knowledge was so great that one day Baer, who arrived in London, was asked: “You are Baer, but which of the Baers: a zoologist, a geographer or an anthropologist?” Embarrassed Baer replied: "I'm only Baer ... and all together." Baer was a remarkable embryologist (the founder of modern embryology) [in 1826 he discovered the egg of mammals and humans. Further, Baer first gave an idea of the germ layers and established the first stages of laying the notochord, brain, heart and other organs in vertebrates (1828-1837)] and an evolutionary biologist, Darwin's predecessor [Darwin in historical essay evolutionary views in his book "The Origin of Species" emphasized that Baer's evolutionary views are based "mainly on the laws of geographical distribution"], an oceanologist and founder of the science of fisheries.

Baer is also known as a geographer and traveler who did a lot to understand the geography of Russia, a geomorphologist who studied the causes of the asymmetry of river valleys and the origin of the Caspian hillocks, called Baer, and finally a major historian of geography. Baer was one of the founders of the Russian Geographical Society.

As a traveler, Baer is especially famous for his expeditions to Novaya Zemlya and the Caspian Sea.

Baer was the first scientist to visit Novaya Zemlya, who actually discovered its flora and fauna for science, and pioneered its geological and geographical study. Along with the valuable collections brought from Novaya Zemlya, Baer's remarkably expressive characteristics of the nature of Novaya Zemlya deserve to be noted. They portray him as a complex thinker-geographer who was able to identify deep connections organic world with the environment.

During the Novaya Zemlya expedition, Baer collected marine fauna in the throat of the White Sea and near the coasts of Novaya Zemlya, noted the richness of the fauna of these areas and established 70 different species in the collected materials, creating the first faunal list for the Barents Sea.

Three-year studies of the Caspian and its fauna, primarily the fish fauna, allowed Baer to draw up "Proposals for the best organization of the Caspian fishery", containing a presentation of the first rational foundations of fisheries, measures to protect fish from predatory fishing and to protect their spawning grounds.

One of Baer's practically important contributions to National economy was a recommendation to them to use the Caspian herring as a food product.

Baer was the first to give a number of valuable generalizations for understanding the phenomena of biological productivity in marine waters. In the course of his research, Baer described the Krasnovodsk Bay and Cheleken Island, significantly developing the then ideas about the geography of the eastern shores of the Caspian Sea.

He gained great fame for his Caspian studies, in which Baer, along with a broad hydrological survey of the Caspian, expressed considerations that glorified him in geography about the reasons for the asymmetry of river valleys and a hypothesis about the origin of "Baer's hillocks".

Baer was born an Estonian nobleman, was born on February 17, 1792 in the family estate of Pina in the Ierven district of the Estland province. In 1807, he was assigned to a noble school in Revel, and after graduating in 1810, he entered the Medical Faculty of Derpt University. In 1812, he decided to be a physician in a detachment of the Russian army, which was stationed near Riga. With the retreat of Napoleon's army, he returned to Dorpat and in 1814 completed his course of study, defending his doctoral dissertation in Latin: "On endemic diseases among Estonians." Upon graduation, Baer went to Vienna to complete his education. Here, under the influence of a Dorpat comrade, Parrott became interested in mountain excursions and natural science. Soon he leaves Vienna, goes on foot through Linz, Walzburg, Munich, Regensburg and Nuremburg to Würzburg. Since the autumn of 1815, he began to study with prof. Dollinger comparative anatomy of animals.

Already in his first articles and reports (“How Life on Earth Developed”, 1822, “On the Kinship of Animals”, 1825, etc.), Baer expressed a number of profound evolutionary ideas, created a family tree of animal development, and wrote about the “gradual improvement” of organisms ( starting from microorganisms) as a result of “changes earth's surface". Later, in 1834, in the article "The Universal Law of Nature, Manifested in All Development", Baer directly stated that everything in nature develops and is "in a transient state."

In 1816, Baer received an invitation from the University of Königsberg to take the place of a prosector (assistant professor), from 1822 he became an ordinary professor, and from 1826 - director of the anatomical institute. Baer has developed scientific activity and, while studying the embryology of birds, and then the history of the development of other vertebrates, in 1826 he made a brilliant discovery: he first found the egg of mammals (first in a dog) and reported this to the Academy of Sciences. The following year, a continuation of this work appeared, which constituted an era in embryology.

In 1827, Baer received an offer from the Academy of Sciences to take the vacant seat of an ordinary academician. Baer had a desire to return to his homeland. In 1829 he arrived in St. Petersburg, but he did not like the work environment there, and in 1830 he returned to Konigsberg. Four years later, he finally resolutely left Koenigsberg and moved with his family to St. Petersburg.

At the Academy of Sciences, he changed his former specialty and became interested in geography, anthropology and ethnography. For research in these areas, he repeatedly traveled through the vast expanses of Russia. The reasons for this change were, on the one hand, the lack of a suitable environment at the Academy for the continuation of his previous work, and on the other hand, the advice of doctors to change the ten-year Koenigsberg sedentary image life on a more mobile to restore shaken health.

In 1837, the Academy of Sciences organized an expedition to Novaya Zemlya on two small ships (the schooner "Krotov" and the boat "Saint Elisey"), the conductor of the corps of naval navigators A. K. Tsivolka was appointed commander, and the head of the expedition was K. M. Baer, and with him six people of service personnel. On June 19, 1857, the expedition departed from Arkhangelsk.

Having visited the shores of the Kola Peninsula, the expedition reached Matochkin Shar on July 19 and studied both banks of the strait in geological, botanical and zoological terms. Having overcome the ice in Matochkin Shar with great difficulty, the scientists on karbas reached the Kara Sea, but, caught in bad weather, almost died and, having experienced great hardships, returned to their ships. The purpose of the expedition - the description of the north-eastern coast of Novaya Zemlya - remained unachieved. On the other hand, Baer visited a number of points on the western coast of Novaya Zemlya and achieved significant success in his description. Baer established the presence of 135 plant species on Novaya Zemlya (over the next 100 years, this number was increased by only 13 species). Many valuable comprehensive observations have been made on the climate and its effects on vegetation. Baer's faunistic studies and the large collections he collected were of great importance. Baer's satellite Leman made valuable geological surveys.

The expedition stayed on Novaya Zemlya for six weeks, after which it set off on the return journey and on September 12, 1837 returned to Arkhangelsk. Baer was the first scientist to visit those places. He studied them in geological, topographical, meteorological, botanical and zoological terms, explained the continental origin of Novaya Zemlya and the landscape features inherent in it. Baer made a major mistake by making a hasty conclusion about the inaccessibility of the Kara Sea for navigation, and this view, due to its authority, lasted in science for over 30 years, until it was refuted by facts.

In 1839, Baer and his eldest son sailed through the islands and skerries of the eastern Gulf of Finland in order to study traces of the movement of the glacier and the question of the level of the Baltic Sea.

Since 1839, Baer began to publish together with Acad. G.P. Gelmersen special journal on German at the Academy of Sciences under the title "Materials for the knowledge of the Russian Empire and neighboring countries of Asia."

In 1840, Baer was again in the north, visiting the shores of the White Sea and the Kola Peninsula.

In 1845, Baer took part in a circle of our academicians (V. Ya. Struve, G. P. Gelmersen, P. I. Koeppen, A. F. Middendorf), which greatly contributed to the establishment of the Russian Geographical Society, and then took an active part in the newly opened Society (member of the council, chairman of the ethnography department, member of the meteorological commission, compiler of instructions, etc.).

In 1851 and 1852 made several trips to the shores of the Baltic Sea, to the Aland Islands and to Lake Peipus (Chudskoye) to study the reasons for the decrease in fish catches. The result of these trips was the "Research on the state of fisheries in Russia", which formed the basis of Russian fishery protection legislation.

In 1853, the Russian Geographical Society and the Ministry of State Property, by mutual agreement, decided to send a scientific expedition to the Volga and the Caspian Sea for a comprehensive scientific research sea and its fauna, on the basis of which it would be possible to draw up fishing rules. The reason for the expedition was the complaints of fishermen about the scarcity of fish. Baer was put at the head of the expedition, the other members were: the Russian naturalist N. Ya. Danilevsky and A. Schultz. On June 14, 1853, they left for Moscow, Nizhny Novgorod, and from there, partly by water, partly along the coast, they headed along the Volga to Astrakhan; excursions to fish gangs, to the Mangyshlak peninsula, to the fortification of Novopetrovskoye.

In 1854 they visited Sarepta, Kamyshin, Astrakhan, Novopetrovsky, the islands and the mouth of the Ural River, went again to Astrakhan, then to the western shore of the Caspian Sea, the Black Market at the mouth of the Terek and the Astrakhan salt lakes.

In 1855 they went by steamer to the mouth of the Kura, then by boat to Lankaran, from there to Baku; we examined oil sources, went to Shemakha, climbed up the Kura, to Lake Sevan and to Tiflis.

In 1856, they arrived in Astrakhan in the spring, here Baer fell ill with a fever, but within a month he cured himself and went to the Manych valley, from where he sailed across the Caspian Sea in the summer on a steamer with the Astrakhan governor; In the fall I went back to the Black Market. In 1857, Baer returned to St. Petersburg, leaving N. Ya. Danilevsky and D. Schultz to continue research.

The result of the work was a series of articles published in the "Bulletins" of the Academy of Sciences in German and French with the author's additions entitled "Scientific notes on the Caspian Sea and its environs" (this is "Kaspische Studien"), which sets out the hypothesis of a catastrophic decrease in the level from the formation of sand mounds on the area freed from water, which later received the name "Baer mounds". In addition to presenting the results of studying the banks, beds, temperatures, water salinity, etc., in the same “Notes” Baer explains the reason for the asymmetry of the banks of Russian meridionally flowing rivers - this is the well-known so-called “Baer's law”. This law was formulated too narrowly by Baer (it applied only to meridional flowing rivers), although in reality rivers of any direction are subject to it. Obviously, Baer did not know the works of the French physicists Coriolis (1835) and Babinet (1849). In addition, the phenomenon of asymmetry of river banks is very complex and, as science has now established, cannot be explained by one reason.

In 1861, Baer was again on an expedition, this time on research Sea of Azov. It seemed to the authorities of the Novorossiysk Territory that the sea was becoming clogged with ballast thrown out by ships, and was becoming catastrophically shallow. As a result, it was proposed to apply for a ban on navigation by sea for large ships. The Russian Geographical Society and the Academy of Sciences jointly equipped an expedition to study this issue. Baer was put at the head of the expedition, who invited the naturalist G. I. Radde to help him. Together they went through Moscow, Kharkov, Yekaterinoslav [Dnepropetrovsk] and along the Dnieper to Nikolaev, then Odessa, Sevastopol, Balaklava, Inkerman, Kerch, Taganrog, along the arms of the Don to Rostov and Novocherkassk. From here, Radde traveled alone to Manych, and then both to Berdyansk, Mariupol [Zhdanov], Yeisk, Genichesk; they visited the northern, western, partly southern shores Sea of Azov and Rotten Sea. As a result of observations at so many points, Baer came to the conclusion that the shores of the Sea of \u200b\u200bAzov, especially the Taganrog Bay, are subject to sand deposits, mainly near the coast, which does not threaten navigation at all, either now or in the future. Subsequent detailed expedition of 1864-1865. N. Ya. Danilevsky fully confirmed Baer's conclusions.

In addition to expeditionary research work, Baer was also interested in the history of geography and published a number of works on this subject (“Biography of I.F. Kruzenshtern”, “On the merits of Peter the Great in the spread of geographical knowledge”, “Bering and Chirikov”, etc.).

Until the end of his life, Baer remained a convinced evolutionist, or, as they said then, a transformist. In a report on the New Guinean tribes on April 8, 1859, that is, the year Darwin's On the Origin of Species was published, he continued to develop evolutionary ideas and spoke of changes in the organic world "in the sequential order that paleontology indicates to us."

Shortly before his death, the 80-year-old Baer also expressed critical remarks about Darwin's teachings, believing that the struggle for existence and natural selection are not sufficient for the constant emergence of new forms of organisms, and continuing to see their variability mainly as a result of the influence of the environment. At the same time, Baer by no means denied the importance of Darwinism and, not without reason, attributed to himself "the preparation of the Darwinian doctrine."

In 1867, Baer moved to the quiet city of Derpt, where he died on November 16, 1876. A monument was erected to him there.

The name of Baer was given to a cape on the northern island of Novaya Zemlya and an island in the Taimyr Bay, and as a term it was included in the name of "Baer hillocks" in the Caspian Sea.

Bibliography

Biographical dictionary of figures of natural science and technology. T. 1. - Moscow: State. scientific publishing house "Great Soviet Encyclopedia", 1958. - 548 p.
Bondarsky M. S. Karl Maksimovich Baer as a geographer / M. S. Bondarsky, Yu. K. Efremov // Domestic physical geographers and travelers. - Moscow: State Educational and Pedagogical Publishing House of the Ministry of Education of the RSFSR, 1959. - S. 214-221.

Karl Maksimovich Baer(Karl Ernst) (1792-1876) - naturalist, founder of embryology, one of the founders of the Russian Geographical Society, foreign corresponding member (1826), academician (1828-30 and 1834-62; honorary member from 1862) of the St. Petersburg Academy of Sciences. Born in Estonia. Worked in Austria and Germany; in 1829-30 and from 1834 - in Russia. Opened the egg in mammals, described the blastula stage; studied chick embryogenesis.

Karl Baer established the similarity of the embryos of higher and lower animals, the consistent appearance in embryogenesis of signs of type, class, order, etc.; described the development of all major organs of vertebrates. Explored Novaya Zemlya, the Caspian Sea. K. Baer - editor of a series of publications on the geography of Russia . He explained the pattern of river bank erosion (Baer's law: rivers flowing in the direction of the meridian in the Northern Hemisphere wash away the right bank, in the Southern Hemisphere - the left. It is explained by the influence of the daily rotation of the Earth on the movement of water particles in the river.).

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Carl Ernst von Baer Teacher of biology Kuzyaeva A.M. Nizhny Novgorod

Karl Ernst von Baer (February 17, 1792 - November 28, 1876) Karl Ernst von Baer, or, as he was called in Russia, Karl Maksimovich Baer, one of the founders of embryology and comparative anatomy, academician of the St. Petersburg Academy of Sciences, president of the Russian Entomological Society, one of the founders Russian Geographical Society. Ichthyologist, geographer, anthropologist and ethnographer.

Baer was born on February 28, 1792 in his father's estate Pin, Estland province (Tartu, Estonia); Baer's father, Magnus von Baer, belonged to the Estonian nobility. Home teachers worked with Carl. In August 1807, the boy entered the noble school in Revel. in 1810 - 1814 he studied medicine at the University of Dorpat and in 1812 - 1813 he had the opportunity to do it practically in a large military infirmary in Riga. In 1814, Baer passed the examination for the degree of doctor of medicine.

To improve in the sciences, Karl Baer went to Germany, where, under the guidance of Dellinger, he studied comparative anatomy in Würzburg; met Nees von Esenbeck, who provided big influence to his mental direction. Since 1817 Baer has been Burdakh's prosector in Konigsberg. In 1819 he was appointed extraordinary, and shortly thereafter, ordinary professor of zoology. In 1826 he was appointed ordinary professor of anatomy and director of the anatomical institute. In the same year, Baer discovered the mammalian egg. In 1828, the first volume of the famous "History of the Development of Animals" appeared in print. In 1829 he was invited as an academician and professor of zoology at the St. Petersburg Academy of Sciences. Johann Dellinger Nes von Esenbeck

In the summer of 1837 he traveled to Novaya Zemlya, where no naturalist had ever been before. In 1839, Baer made a trip to explore the islands of the Gulf of Finland. In 1840 he visited the Kola Peninsula. Baer from 1840 began to publish, together with Gelmersen, a special journal at the academy, called "Materials for the Knowledge of the Russian Empire."

Since 1841, Baer was appointed to the chair of comparative anatomy and physiology at the Medico-Surgical Academy, which was specially founded for him, as an ordinary professor. Cheny works together with the surgeon N.I. Pirogov. In 1851, Baer submitted to the Academy of Sciences a large article "On Man", intended for Yu.I. Simashko and translated into Russian. K. Baer N.I. Pirogov

Since 1851, the system of Baer's travels across Russia began with practical purposes and carried, in addition to geographical and ethnographic research, in the field of applied zoology (to Lake Peipus, the shores of the Baltic Sea, the Volga and the Caspian Sea). In the spring of 1857, the scientist returned to St. Petersburg and became interested in anthropology. He commissioned and enriched the collection of human skulls in the anatomical museum of the Academy of Sciences. In 1862 he retired and was elected an honorary member of the Academy. On August 18, 1864, a solemn celebration of his anniversary took place at the St. Petersburg Academy of Sciences. After the anniversary, Baer considered his career in St. Petersburg irrevocably completed and decided to move to Dorpat. In the early summer of 1867 he moved to a nearby campus.

Baer's Laws The most general characters of any large group of animals appear in the embryo earlier than the less general characters; after the formation of the most general signs, less common ones appear, and so on until the appearance of special signs characteristic of this group; the embryo of any kind of animal, as it develops, becomes less and less like the embryos of other species and does not pass through the later stages of their development; the embryo of a highly organized species may resemble the embryo of a more primitive species, but never resembles the adult form of that species.

The law of germline similarity Karl Ernst von Baer showed that the development of all organisms begins with the egg. At the same time, the following patterns are observed that are common to all vertebrates: at the early stages of development, a striking similarity is found in the structure of the embryos of animals belonging to different classes (in this case, the embryo higher form does not look like an adult animal form, but like its embryo); in the embryos of each large group of animals, common characters are formed earlier than special ones; in the process of embryonic development, there is a divergence of signs from more general to special.

On November 16 (November 28), 1876, Baer died quietly, as if he had fallen asleep. In November 1886, a monument to Baer was erected in Tartu. Monuments are also installed at the entrance to the Zoological Museum of the Zoological Institute of the Russian Academy of Sciences and in the Library of the Academy of Sciences (BAN) in St. Petersburg. In 1864, the prize was approved to them. Baer. K. Baer on the Estonian banknote of 2 kroons Karl von Baer is depicted on the banknote of two Estonian kroons.

Karl Ernst Baer (Karl Ernst von Baer, or, as he was called in Russia, Karl Maksimovich Baer, was born on February 17, 1792 in the town of Pip, in the Gerven district of the Estland province. Baer's father, Magnus von Baer, belonged to the Estonian nobility and was married to his cousin Julia von Baer.Karl had home teachers.He studied mathematics, geography, Latin and French, etc. Eleven-year-old Karl already familiarized himself with algebra, geometry and trigonometry.

In August 1807, the boy was taken to a noble school at the city cathedral in Reval. In the first half of 1810, Karl completed the course of the school. He enters Dorpat University. In Dorpat, Baer decided to choose a medical career.

In 1814, Baer passed the examination for the degree of doctor of medicine. He presented and defended his dissertation "On Endemic Diseases in Estonia". Baer went abroad, choosing to continue his medical education in Vienna. Professor Burdakh offered Baer to join him as a dissector at the Department of Physiology at the University of Königsberg. As a dissector, Baer opened a course on the comparative anatomy of invertebrates, which was of an applied nature, since it consisted mainly of showing and explaining anatomical preparations and drawings.

In 1826, Baer was appointed ordinary professor of anatomy and director of the anatomical institute, relieving him of his duties as a dissector until now.

In 1828, the first volume of the famous "History of the Development of Animals" appeared in print. Baer, studying the embryology of the chicken, observed that early stage of development, when two parallel ridges form on the germinal plate, subsequently closing and forming a brain tube. Baer believed that in the process of development, each new formation arises from a simpler pre-existing basis. Thus, in the bud appear first general fundamentals, and more and more special parts separate from them. This process of gradual movement from the general to the specific is known as differentiation. In 1826 Baer discovered the eggs of mammals. This discovery was made public by him in the form of a message addressed to the St. Petersburg Academy of Sciences, which elected him as its corresponding member. Another very important discovery made by Baer is the discovery of the dorsal string, the basis internal skeleton vertebrates.

At the end of 1834, Baer was already living in St. Petersburg. From the capital summer scientist In 1837, he traveled to Novaya Zemlya, where no naturalist had ever been before.

In 1839, Baer made a trip to explore the islands of the Gulf of Finland, and in 1840 visited the Kola Peninsula. Baer from 1840 began to publish, together with Gelmersen, a special journal at the academy, called "Materials for the Knowledge of the Russian Empire."

Since 1841, the scientist was appointed ordinary professor of comparative anatomy and physiology at the Medico-Surgical Academy.

In 1851, Baer submitted to the Academy of Sciences a large article "On Man", intended for Semashko's "Russian Fauna" and translated into Russian.

Since 1851, a series of Baer's travels around Russia began, undertaken for practical purposes and involving Baer, in addition to geographical and ethnographic research, in the field of applied zoology. He conducted expeditions to Lake Peipsi and the shores of the Baltic Sea, to the Volga and the Caspian Sea. His "Caspian studies" in eight parts are very rich in scientific results. In this work of Baer, the eighth part, “On the General Law of the Formation of River Channels,” is most interesting. In the spring of 1857 the scientist returned to St. Petersburg. Now Baer devoted himself mainly to anthropology. He tidied up and enriched the collection of human skulls in the anatomical museum of the Academy, gradually turning it into an anthropological museum.

In 1862 he retired and was elected an honorary member of the Academy.

On August 18, 1864, a solemn celebration of his anniversary took place at the St. Petersburg Academy of Sciences. After the anniversary, Baer considered his career in St. Petersburg finally completed and decided to move to Dorpat. In the early summer of 1867 he moved to his native university town.

The main works of the scientist are the Message on the development of the egg of mammals and humans (Epistola de ovi mammalium et hominis genesi, 1827), the history of animal development (Über die Entwickelungsgeschichte der Thiere, 1828; 1837), the study of the development of fish (Untersuchungen Entwickelung der Fische, 1835).