THE WAY IN WHICH NEW PLANTS ARISE 153 



the result is a structure from which a new sporo- 

 phyte is formed. The ovary may be compound and 

 contain many embryo sacs, in which case a separate 

 pollen tube will be necessary to fertilize each one. 

 The result will be many seeds or embryos separate 

 or in a many-seeded fruit. The growth of the pol- 

 len tube down through the pistil to the embryo sac 

 may take only a few hours, or it may occupy a year, 

 as in the pines. Shortly after the fertilization of the 

 egg it begins to grow and divide until an embryo 

 plant of the sporophytic generation is formed, hav- 

 ing possibly a root, a stem, and one, two, or more 

 seed leaves with the main growing point of the 

 future stem. 



