EMBRYOGENESIS IN THE LYCOPODINEAE 



109 



the axis of the archegonium, Fig. 25a-c. The suspensor undergoes 

 vacuolation and further elongation, with only an occasional transverse 



<, g,.. '> 



Fig. 25. Embryogeny in Selaginella 



A-G, Selaginella spimdosa. A, Longitudinal section of archegonium, a, showing 

 newly divided zygote. B, The same, slightly older: the embryo has lengthened; the 

 outermost cell, su, will become the suspensor, the innermost or embryonic cell, e, 

 will give rise to the rest of the embryo. C-F, Stages in the development of the 

 embryo, showing the very considerable enlargement of the suspensor, the division 

 of the embryonic cell into quadrants and octants, the positions of the successive 

 walls being shown, I-I, II-H, etc. G, A well-developed embryo showing the shoot 

 apex, s, the first leaf, /j, and its ligule, %, the second leaf, A, the first root or rhizo- 

 phore, r, the incipient vascular strand, the foot, /, and the suspensor, su. H-L, 

 Selaginella denticiilata. The embryo undergoes considerable elongation and 

 repeated divisions by transverse walls before the distal embryonic cell divides 

 longitudinally. A shoot apical cell, s, results from an oblique cleavage of a distal 

 cell. (All X 350; after Bruchmann.) 



division, whereas the distal cell grows and divides to form the main 

 body of the embryo (Bruchmann, 1897). The embryonic cell first 

 divides by two vertical walls at right-angles to each other, and then by 



