Colchicine is known to be the mitotic poison. How?

Colchicine is considered to he the mitotic poison because
(i) It is an alkaloid obtained from the conns of Autumn crocus. This alkaloid inhibits the formation of spindle by preventing assembly of microtubules.
(ii) The chromosomes duplicate but they remain within the same cell, increasing the number of chromosomes. As a result, the colchicine treated meristematic cells show doubling of chromosome.