PTERIDOPHYTA 



269 



single binucleate neck canal cell, a very inconspicuous ventral canal cell, 

 and an egg. 



Embryo. The eml^ryo of Botrijchium dissectum and that of Helmintho- 

 stachys are uniciue in that a suspensor is developed, but in all the other 



H G 



Fig. 225. Sex organs of Ophioglossaies. A, antheridium of Ophioglossum vulgcdum, 

 X150; B, antheridia of Botrychium virginianum, X200; C, sperm of Ophioglossum; D to G, 

 development of archegonium of Ophioglossum vulgatum, X225; D, first division of initial; 

 E, young archegonium with two neck cells, central cell, and basal cell; F, later stage, show- 

 ing division of central cell; G, mature archegonium; H, young embryo of Botrychium vir- 

 ginianum, X250. {B and H, after Jeffrey; others after Bruchmann.) 



Ophioglossaies none is present. The first wall in the fertilized egg is 

 transverse and usually a quadrant stage is formed, but the subsequent 

 divisions are irregular and rather indefinite (Fig. 225//). The embryonic 

 organs are differentiated rather late, and so it is not possible to assign 

 them to definite quadrants. The entire inner portion of the embryo 

 forms the foot, while the outer portion gives rise to the root, stem, and 



