i6 THE STORY OF PLANT LIFE 



cells there are paternal and maternal chromosomes 

 in pairs ; in the spore mother cells they are associated 

 in pairs, the paternal and maternal parts of each 

 pair congregating at different poles. So two cells in 

 place of each former one are paternal, two maternal, 

 at each pole. Each chromosome divides, and one- 

 half of them travelling to one pole is paternal, the 

 other going to the opposite pole is maternal, making 

 four. Nuclear division may occur in cell-division 

 vegetatively, since each new cell must have a nucleus 

 by the division of one original into two new ones. 

 In reproduction the special cells divide, and in fusing 

 the contents interchange. 



In the case of propagation vegetatively adventitious 

 roots may be produced, springing from the stem base, 

 or such roots may develop on rhizomes, runners and 

 other creeping stems at joints where leaves or buds 

 form. Without such adventitious roots it would not 

 be possible to strike cuttings, and in layers they are 

 also developed. Suckers are dormant buds developed 

 below the surface. 



Adventitious buds may be developed on the stem, 

 leaves, and even roots. Or they may form upon 

 detached parts of a plant, as in the begonia leaf, 

 scales of bulbs, etc., and if roots later develop, as is 

 usual, they give rise to a new plant. 



In stems where superficial runners or stolons occur 

 buds develop with adventitious roots at the nodes, 

 and, the internodes dying away, fresh plants 

 spring up. 



