When mitosis is about to take place, they separate from one another and pass to the poles of the nucleus, forming the achromatic spindle.
Here the cell is about to start entering mitosis.
This is imperative if cell mitosis is to continue, as cell division will only occur if cells are kept at body temperature.
If the chromosomes of such cells are selectively stained with a dye such as acetic orcein, stages in mitosis can be observed.
It has been shown that, in cells of Spiro gyra placed under special conditions, amitotic division can be induced, and that normal mitosis is resumed when they are placed again under normal conditions.