ABSTRACT
The discovery of x-ray-induced mutation in Drosophila by Muller in 1927, followed by Stadler in Maize in 1928, provided the necessary impetus for research on the effects of outside agents on chromosomes. The most suitable chemical for the purpose of securing a large number of metaphase plates is colchicine as it causes metaphase arrest by inhibiting the operation of the spindle mechanism. The study of chromosome fragmentation by chemicals has a special significance in bringing out the differential nature of chromosome segments. The effects of different chemical agents and their modes of action have been dealt with in detail by several workers including our group. In the study of the effect of chemical agents on chromosomes, control experiment should be set up with water treatment alone in cases where water is used as the solvent of the chemical agent. The effects are modified by interactions between metals and the addition of external agents.
