XV] 



EMBRYOS OF OPHIOGLOSSACEAE 



307 



Helminthostachys or BotrychiuuL obliqniun. In them the apex of the shoot 

 points from the time of its first appearance directly towards the neck of the 

 archegonium, and there is no curvature seen in the further development. This 

 follows from a comparison of the drawings of Bruchmann from Ophioglossiun 

 viilgatuni and Botrychiiwi Lmzaria (Figs. 292, 293). The apex as before 

 originates from the epibasal hemisphere, an arrangement closely resembling 

 what is seen in those Marattiaceae which have no suspensor. Essentially the 



Fig. 293. Botrychium Ltinaria, L. The lower figure represents an old embryo with 

 well-developed foot (/) ; 7£^] = apex of first root ; j- = apex of the rhizome with the 

 second root, ^2- The endophyte (t-;;) is already in the cells. (X52.) The upper 

 figure is a diagrammatic section of a seedling, with six to eight roots, of which 

 three are in the plane of section. y=foot; Wj = first root; w = other roots; 

 x = apex of rhizome; b^ — (^3 = developing leaves. ( x 6.) (After Bruchmann.) 



same plan of construction holds for all Leptosporangiate Ferns, but with 

 greater precision in the segmentation, which accords with that greater pre- 

 cision seen in all their growing points in the adult state. There is, however, 

 a difference in the orientation of their embryos relatively to the axis of the 

 archegpnium, their polarity being defined by the first cleavage of the zygote 

 (Fig. 294). For here the first wall is approximately in a plane which includes 

 the axis of the archegonium, to which consequently the axis of the embryo 

 is approximately at right angles. This goes along with the fact that the 



