Susceptibility of Colchicum and Chlamydomonas to Colchicine

Abstract

1. Excised roots of Colchicum cultured in small vials are immune to 1 per cent colchicine. 2. Mitosis in excised roots of C. byzantinum can be partly disrupted by 2.5 per cent colchicine and entirely blocked by 5 per cent. Mitosis in C. autumnale is first disrupted and eventually completely blocked by 10 per cent colchicine. The effects are typical of those produced in other angiosperms. 3. It is concluded that the immunity of Colchicum results from an extramitotic protection, not from a difference in the mitotic mechanism. 4. Chlamydomonas pseudococcus, as judged by the rate of reproduction, is resistant both to colchicine and acenaphthene. This immunity is not specific for colchicine and may represent the type of resistance found in organisms which do not naturally contain colchicine.