NATURE OF PLANTS 105 



and note the character of the plant that develops from it. As 

 has been stated this spore is never discharged from the ovule 

 within which its entire growth occurs. The first indications of 

 germination are seen in the enlargement of the spore and the 

 division of its nucleus into two nuclei, which separate and move 

 to either end of the spore (Fig. 77, A). The food for the 

 nourishment of the growing megaspore is derived from the cells 

 of the nucellus which are dissolved and absorbed as the mega- 

 spore increases in size. Each of the two nuclei at the end of the 

 spore divides again, thus forming two nuclei at either end. 

 This process is repeated once more so that we now find four 

 nuclei at the ends of the spore which has become somewhat elon- 

 gated (Fig. 77, B, C). Now a nucleus from each end, the 

 so-called polar nuclei, move toward the center of the spore and 

 fuse, forming one nucleus. This completes the germination of 

 the megaspore and we see that it has grown into a sac-like plant 

 consisting of seven cells, or nuclei imbedded in a mass of proto- 

 plasm (Fig. 78). The cells of this minute plant differ in char- 

 acter and perform very different duties. For example, the larger 

 cell toward the micropylar end of the plant is the female cell or 

 egg cell. It will be called the female gamete because it unites 

 with another cell, the male gamete. The two small cells near 

 the female gamete are the synergidae or cells that assist in the 

 nourishment and later development of the female gamete. The 

 two cells fusing in the center of the plant form the endosperm 

 nucleus which later by repeated division produces a mass of 

 nourishing cells that fill the space within the sac. The three 

 cells at the bottom of the sac, known as the antipodal cells, may 

 increase ih number and take part in the later growth, but as a 

 rule they are disorganized and used for food. They are often 

 provided with cell walls, the other cells consisting only of a 

 nucleus and a varying amount of cytoplasm. This plant formed 

 by the germination and growth of the megaspore is called the 

 female gametophyte, because it contains the female gamete, and 

 you will see that a corresponding plant appears in the ferns and 

 other groups of plants. 



Returning now to the microspore, we find that its germination 



