2. Dislocatiows: Rearrangement of chromosome material without any alteration in the total mass of the nucleus. Here should be classified various alterations known to occur spontaneously, such as attachment, duplication, translocation, fragmentation, etc. 3. Transformzations: Alteration of the morphological characters of the chromosomes invariably connected with a change of the total mass of the nucleus, although often affecting different chromosomes independently. Transformation is believed to have occurred in course of the evolution of the Crepis species, which in most cases markedly differ in the sizes and shapes of their individual chromosomes. 4. Novations: A presumed phenomenon of formation of the chromosomes de novo, which was called to account for some apparently otherwise inexplicable cases of appearance of nsew large V-shaped chromosome structures. As will be shown in the following, this last type should very probably be merged with dislocations.