66 



PLANT LIFE. 



(see fig. 76). In many of the seed-plants the egg divides 

 several times in parallel planes, forming a 

 short filament, the suspensor (figs. 79-82). 

 The terminal cell of this row may then 

 give rise to an embryo, as just described, 

 or this terminal cell and an adjacent one 

 may take part in forming the embryo. In 

 this case the terminal cell, by its divisions, 

 either produces the primary leaf or leaves, 

 t produces the primary stem and 

 r, s, ceils of the suspen- leaves ; while the second cell gives rise to 



sor; a, a, fi, cells from ° 



:1V H.Khiy r ^: the P rimar y stem and root > or to the 



fied. -Afur Sachs. primary root alone (see figs. 80-82). 

 The two primary members formed 

 from the root hemisphere of fernworts 

 are not always permanent. The foot is 



Fig. 79.— A very young or 



embryo of the onion. 



Fig. 80. Fig. 81. Fig. 82. 



Fig. 80.— A very young embryo of shepherd's-purse. Suspensor, s, s. just completed, 



and first four cells of embryo formed by division of terminal one ; the sei ond 1 ell, 



/>, is to produce part oi the root. Highly magnified. — After Hanstein 

 Fig. 81. — An older stage of the same. /.', embryo; /•', /■". two cells resulting from 



division of b. fig. 80; *. s. suspensor. The shaded cells produce the skin and the 



vascular bundles Highly magnified.— After Hanstein. 

 Fig. 82.— An older embryo of same. £, embryo; /. /, primary leaves; .9/. apex of 



stem ; r, primary root ; re, first layer of root-cap; .r, suspensor. Cells shown only 



in part. Less magnified than preceding.- \fter Hanstein. 



