SPERMATOPHYTES 



237 



sperm tissue, which finally replaces the nucellar tissue. In both Tumboa 

 and Gnetum, therefore, the general behavior of the angiosperm egg has 

 been reached. 



Conclusions. — It is evident that Gnetales show remarkable angio- 

 sperm tendencies, which may be summed up as follows : true vessels in 



537 536 



Figs. 535-537. — Embryo of Ephedra: 535, one of the proembryonal cells whose 

 nucleus has divided and which has begun to form a tubular elongation; 536, both 

 nuclei in the tubular elongation and a wall formed between them, one cell {s) elongat- 

 ing to form the suspensor, the other (e) to form the embryo; 537, embryo beginning to 

 form at the end of the suspensor. — After Land. 



the secondary wood ; the final elimination of archegonia and the organiza- 

 tion of independent eggs ; and an embryogeny in which free nuclear divi- 

 sion in the fertilized egg has disappeared. The elimination of arche- 



