30 HEREDITY AND EVOLUTION IN PLANTS 



membrane then disappears, and, by a complicated mechan- 

 ism, not entirely understood, the two halves of the chro- 

 mosomes are separated and carried apart to opposite sides 



of the cell. After this division of the nucleus, a new cell- 

 wall forms, dividing the entire cell into halves; new nu- 

 clear membranes develop, and the chromosomes in each 



