Karl Ernst von Baer

For more information on Karl Ernst knight von Baer, visit Britannica.com.

[b. Piep (Estonia), February 28, 1792, d. Tartu (Estonia), November 28, 1876]

Famed for his discovery of the mammalian egg cell, Baer also discovered the membranes around the embryo and described their function. He formulated basic principles of embryonic development. The purpose of early development of a zygote (fertilized egg) is to form layers of tissue, which then form all the various organs of the body. An embryo develops from simple to complex; general characteristics appear before special characteristics. In their early stages, young embryos of various species resemble one another, but as each species develops it moves progressively away from this resemblance.

The Estonian anatomist and embryologist Karl Ernst von Baer (1792-1876) was the first to describe the mammalian ovum. He also developed the germ-layer theory, which became the basis for modern embryology.

Karl Ernst von Baer was born in Piep on Feb. 29, 1792. He began his medical studies at the University of Dorpat in Estonia in 1810, and after graduating in 1814 he continued his studies at Vienna. After realizing his limitations as a practitioner, he studied comparative anatomy at the University of Würzburg, where he was taught by the influential anatomist Johann Döllinger. On completion of his studies, Baer accepted a position as prosector in anatomy at the University of Königsberg, and in 1819 he was appointed associate professor of zoology there. In 1822 he achieved the rank of professor.

At Königsberg he undertook his famous studies in embryology in collaboration with C. H. Pander. He worked first on the embryology of the chick but later investigated the problem of identifying the structure of the ovum of the dog and found it to be a small yellow spot floating in the follicular fluid. As a result of this work, he published in 1827 the first description of a mammalian egg, Epistola de ovi mammalium et hominis genesi (On the Origin of the Mammalian and Human Ovum). His reputation was further increased by the publication of his most famous work, Entwicklungsgeshichte der Tiere (1828-1837; Developmental History in Animals). In this work he developed the germ-layer theory, in which he held that in vertebrate eggs four "layers" of cells are formed and that each layer always gives rise to certain tissues in the adult organism. (The two middle layers were later regarded as one.) In this same work he outlined his discovery of the notochord in the chick embryo. He described it as a rod of cells which runs the length of the vertebrate embryo and around which the future backbone is laid down.

Laws of Development

Baer's work on the embryological development of animals led him to frame four laws. In these laws he was concerned with the question of how closely the development of an embryo of one species resembles that of other species and how closely its various embryonic stages resemble the adult stages of other species. His laws state that the embryo of a given species never resembles the adult of another species and that the embryos of even the most similar species do not pass through the same states but, rather, become progressively different from each other. These "laws of development," though much misunderstood by other biologists and in some cases used by them to support opposite views, were fruitful in later interpretations of embryology and evolution. Herbert Spencer used Baer's law (later known as the biogenetic law) to support his theory that the world is becoming increasingly differentiated and complicated.

In 1834 Baer left Germany to take up the position of librarian of the Academy of Science at St. Petersburg. In this position he advised the Russian government on a number of scientific matters. In 1837 he led a scientific expedition into Arctic regions, and from 1851 until 1856 he studied Russian fisheries and suggested many improvements. He retired to his native Estonia and died on Nov. 28, 1876, in Dorpat.

Further Reading

There is a very good account of Baer's biological work and influence in Edward Stuart Russell, Form and Function: A Contribution to the History of Animal Morphology (1916). Information is also in Joseph Needham, A History of Embryology (1934; 2d ed. 1959); Arthur William Meyer, The Rise of Embryology (1939); and Jane M. Oppenheimer, Essays in the History of Embryology and Biology (1967).

Additional Sources

Baer, Karl Ernst von, Autobiography of Dr. Karl Ernst von Baer, Canton, MA: Science History Publications U.S.A., 1986.

Karl Ernst von Baer

Karl Ernst von Baer (28 February [O.S. 17 February] 1792 – 28 November [O.S. 16 November] 1876) was a Baltic German biologist and a founding father of embryology.

Statue of Karl Ernst von Baer on Toome Hill, Tartu. As a tradition, students wash the head of statue with champagne every Walpurgis Night^[1].

Contents 1 Life 2 Contributions 2.1 Embryology 2.2 Baer's laws (embryology) 2.3 Baer's law (geology) 2.4 Explorer 2.5 Entomology 2.6 Meteorology 2.7 Subjective biology 3 Works 4 Further reading 5 References 6 External links

Life

Karl Ernst von Baer was born in Piibe manor (German: Piep), now in Rakke, Lääne-Viru, Estonia; many of his ancestors had come from Westphalia. A knight by birthright, his full name was Karl Ernst Ritter von Baer, Edler von Huthorn. He was educated at the Cathedral School in Reval (Tallinn) and the University of Dorpat (Tartu). He continued his education in Berlin, Vienna, and Würzburg where Döllinger introduced him to the new field of embryology.

In 1812, Baer was a volunteer in the war against Napoleon's invasion, serving as doctor^[2].

In 1817, he became a professor at Königsberg University (Kaliningrad) and full professor of zoology in 1821, and of anatomy in 1826. In 1829 he taught briefly in St Petersburg, but returned to Königsberg. In 1834 Baer moved back to St Petersburg and joined the St Petersburg Academy of Sciences, first in zoology (1834–46) and then in comparative anatomy and physiology (1846–62). His interests while there were anatomy, ichthyology, ethnography, anthropology and geography. The last years of his life (1867–76) were spent in Dorpat (Tartu), where he became one of the leading critics of the theories of Charles Darwin.

He was elected a foreign member of the Royal Swedish Academy of Sciences in 1850.

A statue honouring him can be found on Toome Hill (Toomemägi) in Tartu. The two kroons (2 krooni) Estonian banknote bears his portrait.

Contributions

Embryology

Karl Ernst von Baer.

He studied the embryonal development of animals, discovering the blastula stage of development and the notochord. Together with Heinz Christian Pander and based on the work by Caspar Friedrich Wolff he described the germ layer theory of development (ectoderm, mesoderm, and endoderm) as a principle in a variety of species laying the foundation for comparative embryology in the book Über Entwickelungsgeschichte der Thiere (1828). In 1826 Baer discovered the mammalian ovum. The first human ovum was described by Allen in 1928.(1) In 1827 he completed research "Ovi Mammalium et Hominis genesi" for Saint-Petersburg's Academy of Science (published at Leipzig^[3][4]) and established that mammals develop from eggs.

Baer's laws (embryology)

He formulated what would later be called Baer's laws of embryology:

1. General characteristics of the group to which an embryo belongs develop before special characteristics.
2. General structural relations are likewise formed before the most specific appear.
3. The form of any given embryo does not converge upon other definite forms but, on the contrary, separates itself from them.
4. Fundamentally, the embryo of a higher animal form never resembles the adult of another animal form, such as one less evolved, but only its embryo.

See also: Recapitulation theory

In old age

Baer's law (geology)

The term Baer's law also refers to the proposition that in the northern hemisphere, erosion occurs mostly on the right banks of rivers, and in the southern hemisphere on the left banks.

Explorer

Baer was interested in the Northern part of Russia and explored Novaya Zemlya in 1837 collecting biologic specimen. Other travels led him to the Caspian Sea, the North Cape, and Lapland. He was a founder and the first president of the Russian Geographical Society.

Entomology

Baer contributed to studies in entomology and was a cofounder of the Russian Entomological Society.

Meteorology

Baer Island in the Kara Sea was named after Karl Ernst von Baer for his important contributions to the research of Arctic meteorology between 1830 and 1840.^[5]

Subjective biology

Baer was a pioneer in studying biological time — the perception of time in different organisms. This approach was further developed by Jakob von Uexküll.

Works

• Karl Ernst von Baer, Grigoriĭ Petrovich Gelʹmersen. "Beiträge zur Kenntniss des russischen Reiches und der angränzenden Länder Asiens". Kaiserlichen Akademie der Wissenschaften, 1839. On Google Books (German)

Further reading

• Oppenheimer, Jane (1970). "Baer, Karl Ernst von". Dictionary of Scientific Biography. 1. New York: Charles Scribner's Sons. pp. 385–389. ISBN 0684101149. 

References

1. ^ Kõik algab munast
2. ^ http://www.booksite.ru/department/center/vel/iki/yel/udi/5.htm
3. ^ http://web.archive.org/web/20060521214120/http://safety.spbstu.ru/book/hrono/hrono/biograf/bio_b/ber_karl.html
4. ^ http://web.archive.org/web/20080319143038/http://www.allpersona.ru/people/72032.html
5. ^ http://www.meteohistory.org/2004polling_preprints/docs/abstracts/tammiksaar_abstract.pdf

1. Wood C, Trounson A. Clinical In Vitro Fertilization. Springer-Verlag, Berlin 1984, Page 6.
2. Medical eponyms
3. Baer, K E v. "Über ein allgemeines Gesetz in der Gestaltung der Flußbetten", Kaspische Studien, 1860, VIII, S. 1–6.

External links

Wikisource has the text of the 1911 Encyclopædia Britannica article Baer, Karl Ernst von.

• Short biography, bibliography, and links on digitized sources in the Virtual Laboratory of the Max Planck Institute for the History of Science
• Overview of Piibe (Piep) manor in Estonian Manors Portal (with a picture of a memorial stone)
• Short biography of K.E.v.Baer
• Estonian banknotes
• NNDB Profile of K.E.v.Baer

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