no GERMINATION OF THE GAMETOSPORE 



54. The Germination of the Gametospore and the Formation 

 of Seed. The first indication of the germination and growth of 

 the gametospore is seen directly after fertilization. It becomes 



FIG. 81. Germination of the gametospore of peppergrass, Lepidium: 

 A, micropylar end of the embryo sac showing that the gametospore, g 

 (fertilized female gamete), has developed a cell wall and become attached 

 to the wall of the embryo sac. Compare Fig. 80. B, later stage in the 

 germination e, embryo cell; s, suspensory cells; en, endosperm cells. 

 C, the embryo cell has formed two cells. D, later stage. The embryo cell 

 by further division has formed a spherical mass of cells, here shown in 

 section. Note the appearance of an outer layer of cells, the epidermis, and 

 a central or stem region; s, a few of the suspensory cells. E, still later 

 growth. Two growing regions, the cotyledons are appearing on the side 

 of the stem. F, the micropylar end of the embryo sac, showing the stage 

 of development where the parts of a small plant can be clearly recognized 

 c, cotyledons ; st, stem ending in root, r, to which is still attached the 

 suspensory cells ; en, endosperm cells, now provided with walls, are being 

 absorbed as the plant or embryo enlarges. Note that the embryo and 

 embryo sac are slightly bent to the left. This curvature is due to the fact 

 that the ovule in a great many plants becomes curved in its development 

 with the result that the embryo sac assumes a curved or U-shaped form. 

 This form of the ovule results in a complete bending over of the cotyle- 

 dons against the stem, as shown in the next figure. 



