Introduction ...5 // Material and Methods ...7 // 1 Material ...7 // 2 Methods ...8 // Results and discussion ...13 // 1The general developmental character of populations ...13 // 2 The relation of the developmental character of populations to the geographicalclimatic conditions ...14 // 3 The variability within populations exempflified by the variation in the character “number of days to appearance of the flower primordia“ in the generative plant fraction ...23 // 4 The heritability of the character "number of days to appearance of the // flower primordia“ ...28 // 5 The within-progeny variability in the character "number of days to appearance of the flower primordia” ...31 // 6 The within-progeny variability in a vegetative population ...35 // General conclusions 36 // Summary ...39 // Literature ...41