1.Exposure to 0.04% solution of diazouracil for five hours resulted in an immediate inactivating effect on the spindle mechanism.2.If allowed recovery the chromosomes revert to the resting stage and remain in the resting stage for 48 hours.3.If the effected cells have not differentiated during the 48 hours they will resume division.4.The effected cells divide as either typical tetraploid cells or as binucleate cells.