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 



e 



537 536 



FIGS. 535-537. Embryo of Rphedra: 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- 



