Cytogenetic Studies on Relationships Between Annual Species of Lamium

if the self-fertilization had not failed in a large number of the flowers.An investigation showed that this was the case with about 70 % of the open flowers, and the cause was found to be poor co-ordination in different ways between the stamens and the stigma.C. L. hybrldum X tetraploid L. purpureum 1. Tetraploid hybrids a. C y t 0 log Y As will be described in greater detail below, the F, hybrids are characterized either by a completely normal plant development, or by pronounced dwarfishness.Cytological investigations have been possible only with plants of the first-mentioned kind.Despite the fact that 3 different fixing agents (»Flemming-Benda», »strong Flemming» and »La Cour 2 BE»; cf.DARLINGTON and LA COUR, 1942) and a varied fixing technique were tried, it was not possible to obtain slides clear enough to permit with any degree of certainty of a thoroughgoing distinction of the different kinds of chromosome configuration.Thus here, too, it was unfortunately necessary to use the mode of classification in I's +configurations applied with other species hybrids.