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, 



or it produces the primary stem and 



s %ox- C a 11S a°V h c e ei s is S i?Sm leaves > while the second cell gives rise to 



E^'li^iaZt the P rimar y stem and root > or to th e 

 fied.-After 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 

 embryo of the onion. 



Fig. 80. 



Fig. 81. 



Fig. 82. 

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



and first four cells of embryo formed by division of terminal one ; the second cell, 



6, is to produce part of the root. Highly magnified.— After Hanstein 

 Fig. 81.— An older stage of the same. E, embryo; 6', b", two cells resulting from 



division of b. fig. 80 ; .?. j. 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; st, apex of 



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



in part. Less magnified than preceding.— After Hanstein. 



