70 



OPHIOGLOSSACEAE 



n-T 



[CH. 



Fig. 368. Ophioglossniii retkiilatum L. 

 Longitudinal section through a sporan- 

 gium before separation of the spore- 

 mother-cells : the walls of the vascular 

 tissues are drawn rather more heavily. 



(XIOO.) 



Fig. 369. Ophioglossum viilgaUim L. Portions of sporangia showing the sporo- 

 genous tissue in progress of disintegration. In A the tapetum (A), evidently 

 derived from more than a single layer of cells, has formed a plasmodium 

 with many nuclei, which is beginning to penetrate the sporogenous tissue, 

 St, a sterile sporogenous cell. B shows a more advanced state where the 

 sporogenous cells {sp.) appear in small clusters, or isolated, embedded in the 

 tapetal plasmodium (A): w. = sporangial wall. ( x 100.) 



