288 INTRODUCTION TO EMBRYOLOGY OF ANGIOSPERMS 



sentative of the family Liliaceae, may be described next. As in 

 Luzula, the basal cell cb divides transversely and the terminal cell 

 ca divides longitudinally (Fig. 162A,B). In the next stage, the 

 two cells at ca and the middle cell m divide longitudinally, while 

 the upper cell ci divides transversely into n and n' (Fig. 162C). 

 Of the eight cells formed in this way, n' divides to give rise to o and 

 p; n divides vertically; the two juxtaposed cells of the tier m also 

 divide vertically, although in a somewhat irregular fashion, to pro- 

 duce four cells; and the quadrants at q divide by diagonal walls to 

 produce the octants (Fig. 1Q2D,E). Finally, the tier q gives rise 

 to the cotyledon, m to the hypocotyl and stem tip, n to the initials 

 of the root, o to the root cap, and p to the suspensor (Fig. 162F,G). 



Fig. 162. Development of embryo in Muscari comosum. {After Soueges, 1932.) 



The proembryo of Sagittaria (Soueges, 1931) is similar in some 

 respects to that of Sagina (Fig. 156) described under the dicoty- 

 ledons. The zygote divides transversely into the terminal cell ca 

 and the basal cell cb (Fig. 163 A). The basal cell, which is the larger, 

 does not divide again but becomes transformed directly into a large 

 vesicular structure. 6 The terminal cell undergoes a transverse 

 division to form the two cells c and d (Fig. 1635 ,C). Of these, the 

 lower cell c divides vertically to form a pair of juxtaposed cells, and 

 the middle cell d divides transversely into m and ci (Fig. 163D). In 

 the next stage the two cells at c undergo another vertical division to 

 form quadrants, m also divides vertically, and ci divides transversely 

 (Fig. 163#,F). The quadrant cells at c now divide transversely to 

 give rise to octants (I, I'), the two juxtaposed cells at m become 

 vertically partitioned to give rise to four cells, and the two daughter 

 cells of ci divide to form the cells n, o, h, and s (Fig. 163F-H). With 

 further cell divisions and growth the tiers I and V become trans- 



8 A similar large basal cell occurs in almost all members of the Helobiales and 

 has recently been reported in Lloydia (Bianchi, 1946) belonging to the Liliaceae. 



