Karl Ernst von Baer

Baer, Karl Ernst von (1792–1876), one of the greatest and most versatile naturalists. He graduated from the medical faculty of the University of Dorpat. In 1817, he was appointed prosector, then professor of zoology at the University of Königsberg. From 1827, he was a corresponding member, and from 1828, an ordinary academician of the Russian Academy of Sciences. Baer established the most important laws of the history of individual development. According to Baer, every new formation arises in the process of development from a simpler basis, gradually becoming more complex through the separation of increasingly specialized parts (the process of differentiation in modern formulation). One of Baer's main merits is the establishment of the doctrine of germ layers. Baer first distinguished in the embryo two basic, primary layers, homologous to each other throughout the animal kingdom, and traced their further fate in the animal organism (ectoderm and endoderm in modern terminology). The most prominent merit of Baer in the field of embryology is the discovery of the mammalian egg. Before Baer, the Graafian follicle developing in the ovary was considered the mammalian egg. Baer proved that the true mammalian egg is located inside the Graafian follicle; he found these true eggs in a number of mammals and, in particular, in humans, and traced their development in the oviduct. "The egg," says Baer, "is the common basic form from which all animals have developed, not only abstractly, but also factually and historically" ("De ovi mammalium et hominis genesi", 1827).

The general process of development of all living things, in Baer's opinion, is subject to a universal law that also guides the embryonic development of an individual organism, namely, the principle of teleology. This principle in the process of evolution causes the appearance of increasingly perfect forms, whereby new forms are created under the influence of purely internal, and not external, causes. Baer's doctrine of teleology in many respects resembles the modern doctrine of heredity. Another profound generalization of Baer, confirmed by data from geochemistry, is currently acquiring enormous importance in the study of the biosphere (see), i.e., the region of living substances as a totality of organisms, expressed in weight, chemical composition, and geochemical energy. This generalization indicates that, once having entered living matter, the same atoms remain continuously in the life cycle for millions of years. Baer called his generalization the "law of parsimony" and indicated it for C and N. A series of journeys he made from Novaya Zemlya to the borders of Persia, to study Russia and its productive forces, led Baer to the resolution of numerous geographical questions. The most outstanding generalization of Baer in this field is the famous Baer's law, explaining the character of river banks by the rotation of the earth. This idea, linking geological and geographical phenomena with the general properties of the planet, is now acquiring paramount importance. Following geography, Baer also specialized in the field of anthropology. In this field, he also made a great name for himself, mainly through the system of measuring skulls he built, in development of Retzius's system, which brought unity to the terminology of craniologists and served as the basis for the newest systems. Lit.: Kholodkovsky N. A., K. Baer, his life and scientific activity, SPb, 1893, 2nd ed.