ANQIOSPEBM^. 



433 



developmenb in the apical portion of the embryo sac, there is 

 a corresponding one in the basiil portion. The protoplasm 

 gathers about certain points, and gradually condenses so as 

 to form as many free and naked cells (Fig. 308). These 

 soon become covered with cell-walls, and they then multiply 

 rapidly by fission, until they 

 fill up the embryo sac with a 

 continuous tissue, the endo- 

 sperm. (Consult p. 41, and 

 Kg. 33, A and B.) 



533. The Development of Fig. 308.— Posterior part of the em- 

 +-hQ ■n'Tv,v>-i.TT« IV^rvc QAQ or,<l 'nvyo fac of Viola trimlor. «, itawall;«, 

 the Jlimbryo. {it IgS. d09 ana cavity of the wic ; K, K, youns; endo 



Q1A-V As a+flfpfl nhnvp nnp of sperm-cells which have formed in the 



^J-'JJ' — -^» Staiea aoove, one OI protoplasm, in: Highly magnifled.— 



the first results of the fertili- After sachs. 

 zation of the germ-cell is the formation of a row of from 

 two to many cells, the suspensor or pro-embryo, the first or 

 proximal cell of which is attached to the wall of the 

 embryo sac close to the micropj'le of the ovule ; its distal, or 

 free end, always grows toward the interior of the ovule, and 



Fig. 309. — Embryos of AViv/m cepa. L, verv yoHn^ stage ; c, b. cells of suspensor ; 

 a, the single cell constituting the embryo : x. nn nnfertilizi'd germ cell IX., an older 

 stage, the embryo now two-relief! , e.i, the wall of the embryo sac. III., a still later 

 Much ma'.-nified. — After Sachs, 



its last cell becomes transformed by successive fissions into a 

 several-celled surface (7.,Fig. 310) ; by a continuation of the 

 process a many-celled solid body is formed (77. , Fig. 310) ; 

 partitions then arise in the cells parallel to the surface, and 

 the external layer of daughter-cells thus formed constitutes 

 the dermatogen or primary epidermis (777., Fig. 310), 



