Metaphase analyses in suspension cultures ofHaplopappus gracilisand callus and suspension cultures ofVicia hajastanashowed evidence of extensive alterations in chromosome structure. Anaphase analyses showed very low frequencies of lagging chromosome, multipolar divisions and unequal separation of chromatids; fragments and chromatin bridges were present in relatively high frequencies. It is concluded that the majority of aneuploid cells in these cultures were produced by elimination of chromosomes through a gradual loss of chromatin by fragmentation and chromatin bridges.