FLOW ERS OF IMPA TIEXS FULVA 173 



more or less rounded and push up into the lower end of the micropyle 

 and there degenerate. Then the first endosperm nuclei that are cut oflF 

 move around the embryo and take positions close to and in the micropyle 

 where one or two endosperm cells may be seen cut off (Figs. 29 and 30). 

 These sooner or later degenerate. Then these suspensor-like endosperm 

 cells arise at the micropylar end and persist for a considerable time. The 

 peripheral layer increases to a double layer of cells lining the embryo 

 sac. When the embr\'o has completely filled the sac and the outermost 

 layer of the integument is beginning to take on the peculiar differen- 

 tiation of the seed coat, one of these layers may be still made out. It 

 disappears, however, before the ripening of the seed. 



VIII. Development of Seed Coat and Pericarp 



The behavior of the seed coats after fertilization is worthy of note. 

 At the stage of fertilization the outer integument has risen almost to 

 the level of the inner integument. The two integuments are distin- 

 guishable only for a short distance at the micropylar end. Below this 

 point the tissue is perfectly continuous; no dividing line can be found 

 between the two. This condition results from the growth of the lower 

 part not as two separate integuments that afterwards fuse, but as one 

 tissue that rises as a whole. The inner layer of the integument lying 

 next to the nucellus, and, after the destruction of the nucellus, against 

 the embryo sac, is composed of tabular cells forming a distinct jacket 

 layer (Fig. 28). Very soon after fertilization, degeneration begins in 

 the region about three layers below the jacket cells (Fig. 36). This 

 degeneration spreads inward toward the jacket layer and outward 

 toward the exterior. The jacket layer becomes shrunken to a thin 

 densely-staining layer surrounding the embryo (Fig. 35). The degen- 

 eration of tissue continues outward until only two or three layers remain 

 intact. Meanwhile at the micropylar end the outer integument has 

 grown beyond the inner (Fig. 36). The cells of the outermost layer of 

 the integument become much enlarged and extend outward to form the 

 characteristic ridges of the mature seed coat (Figs. 34, 35 and 36). The 

 cells gradually become filled with the tannin that is so characteristic 

 of the genus. 



The early history of the ovary has been considered above, the devel- 

 opment subsequent to fertilization remains to be considered. The 

 septa have begun to show signs of degeneration in their inner layers 

 before division of the megaspore mother-cell (Fig. 34). This degenera- 

 tion continues rapidly until at fertilization the septa consist each of 



