title: [Programmed and programming embryogenesis using as example the egg tooth of Sauropsids].
abstract: Molecular genetics don't explain the behaviour of cells. It is well known, however, that changes in behaviour precede changes of genetic manifestation. Since only soma cells are working onto-genetically throughout life, they should be thought capable of evolutionary functions. Their precedence is possible because of their surplus of genetic outfit, and the soma cells even must precede from the zygote stage on when their "struggle for life" starts. This notion of Darwin ("struggle for life") should therefore be more emphasized as motor force than his other 2 notions: "variation" and "selection". The phylogenetic development of the egg-tooth of sauropsids is taken as an example for this change-over in evolutionary theorization.
mesh_terms: D000818:Animals; D001502:Beak / Q000196:embryology; D005075:Biological Evolution; D001717:Birds / Q000196:embryology*
vernacular_title: Programmierte und programmierende Embryogenese am Beispiel des Eizahns der Sauropsiden.