452 



OPHIOGLOSSALES 



one another, that of the spike probably originating from one of the latest 

 adaxial segments of the leaf-initial (Bruchmann, /.c., Fig. 55). Though this 

 close proximity of origin of the fertile body to the apex of the sporophyll 

 differs from what has been seen in Ophioglossum viilgatuni, still it has its 

 parallel in the case of Tmesipteris, as already described : the details of 

 segmentation are not the same, but the relation to the whole leaf is 

 similar. Both parts in B. Lunaria retain their active initial cells till 

 about the time of origin of the lateral pinnae : and it is specially to be 



FIG. 251. 



Ophioglossum I'lilgatitin, L. Portions of sporangia showing the sporogenous tissue in 

 two stages of disintegration. In A the tapetum (t), 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, in which an occasional cell (si) is seen disorganised. 

 B shows a more advanced state, where the sporogenous cells (.?/) appear in small clusters, 

 or isolated, embedded in the tapetal plasmodium (f) ; ?y = sporangial wall, x too. 



noted that the origin of these in Botrychium is by a process quite distinct 

 from that of the fertile spike : the latter appears in a median position with 

 a definite apical cell from the first : the pinnae arise in acropetal 

 succession by marginal growth. 1 



The disposition of the sporangia on the fertile spike of Botrychium is 

 essentially similar to that in Ophioglossum, but they differ in being further 

 apart, and not laterally coalescent, except in individual cases. The 

 similarity is most readily recognised in the simplest examples (Figs. 252 A, 

 B, c), in which the number of sporangia may be very small : these are 

 disposed in lateral rows, obliquely facing the sterile frond : their position 



