From Big Medical Encyclopedia

PALEOGENESIS (palingenesis; Greek palin again, repeatedly + genesis origin, an origin) — repetition in an ontogeny of an organism of the stages or signs reminding a structure of «adult» stages of their ancestors. The term «paleogenesis» is entered by Gekkel (E. N of Haeckel) in the course of development by it biogenetic law (see). Gekkel opposed to a paleogenesis a cenogenesis, i.e. a form of ontogenesis, at a cut atavistic stages of development can drop out and be replaced with embryonal devices of a larva to actually developed living conditions. I. I. Shmalgauzen suggested to refer to P. similarity of ontogeneses of organisms of one type, and to a cenogenesis only embryonal devices. Existence in ontogenesis of a set of palingenez can be explained not so much with conservatism of ontogenesis, how many existence of difficult correlative bonds in appreciate implementation of process a gene — a sign.

Bibliography: Severtsov A. N. Morphological patterns of evolution, M. — L., 1939; Shmalgauzen I. I. Problem of Darwinism, L., 1969.

H. N. Vorontsov.