The number of chromosomes in the nucleus of the two spores, pollen-grain and embryo-sac, is only half the number found in an ordinary vegetative nucleus.
Other observers have in recent years demonstrated a similar relation in other genera between the number of chromosomes in the nuclei of the two generations.
In 1902, an American named Walter Sutton noticed that chromosomes duplicated themselves before cells divided so that each new cell had a full copy of the chromosomes.
It forms a part of the 1mm or plastin network of the nucleus and may become impregnated with varying quantities of chromatin stored up for use in the formation of the chromosomes and other nuclear activities.
(2) Metaphase.The chromosomes pass to the equator of the spindle and b,ecome attached to the spindle-fibres in such a way that they form a radiating starthaped figureAster-when seen from the pole of the spindle.