ANGIOSPERMS. 



397 



transverse wall (Fig. 326, //), and the radicle or hypocotyhdonary portion from the 

 lower ; but first of. all an outer and an inner cell are usually separated from one 

 another in each octant by its periclinal walK The outer cells which are dark in 

 Fig. 326/7 are the dermalogen or young epidermis, and its cells continue to divide 

 only by walls at right angles to the outer surface, i.e. by anticlinal walls, no peri- 

 clinal walls being formed ; the inner cells produce the periblem and plerome. The 

 figures /// and IV will give a clear idea of the divisions in these cells. According to 

 Famintzin the initial layers of cells, from which the periblem and plerome proceed, 

 are very early separated from one another and continue to be so; (Fig. 326 does not 

 give this quite correctly and Fig. 327 should be consulted). Subsequently the spherical 



FIG. 326. Embryogeny of Capsella Bursa-pastoris. Stages of the development in the order of the figures / to 

 '/; Vb extremity of the root seen from below, i i, 2 2 first divisions of the terminal cell of the pro-embryo, hh' 

 le hypophysis, -v the suspensor, c the cotyledons, s apex of the axis, TV the root The dermatogen and plerome are 

 laded. After drawings by Hanstein. 



VI; 



the hypophysL, _ , 



shaded. After drawings by Hanstein 



embryo is flattened and becomes first triangular and then cordate in shape (Fig. 

 326 V) by the appearance of two large protuberances, the cotyledons, on the 

 sides of its apex. Meanwhile further differentiations have taken place also at the 

 radicular end of the embryo. The cell of the suspensor adjoining the embryo is 

 made use of to build up the embryo ; its lower transverse wall becomes concave 

 downwards, so that the cell of the suspensor appears as part of the spherical embryo, 

 as the termination of its posterior extremity (Fig. 326 h}; it then divides by a 



