i 3 o 



MORPHOLOGY 



is observed throughout the groups having archegonia. The primary 

 ventral cell, just before the maturity of the archegonium, divides into 

 the ventral canal cell and the egg, and finally all the canal cells dis- 

 organize (fig. 287). 



Figs. 283-287. — Archegonium of Lycopodium clavatum: 283, young archegonium 

 after the first division (periclinal) of the superficial initial, resulting in the primary 

 neck cell (outer) and inner cell; 284, division of neck cell and also of inner cell, the 

 latter division resulting in basal cell and central cell (both shaded) ; 285, division of 

 central cell, giving rise to primary neck canal cell (outermost shaded one) and pri- 

 mary ventral cell (middle shaded one); 286, the completed axial row, consisting of six 

 neck canal cells, the ventral canal cell, and the egg; 287, breaking down of canal cells, 

 leaving a passageway to the egg. — After Bruchmann. 



Embryo. — The embryo of the Lycopodium sporophyte develops in 

 a very characteristic way (figs. 288-293). The fertilized egg divides 

 by a transverse wall, the resulting outer cell being the suspensor cell, 

 and the inner one the embryonal cell (fig. 288). The suspensor cell 

 may or may not divide, but in any event it usually becomes elongated. 

 The suspensor is an organ of the embryo, but does not enter into its 

 permanent structure, which is developed by the embryonal cell. By 

 successive divisions this cell becomes four cells (figs. 289, 290), which 

 are related to each other as unequal quadrants of a sphere. Two of 

 these quadrant cells develop the foot, which is an absorbing organ of 

 the embryo while it is feeding upon the gametophyte. One .of the 

 remaining quadrant cells develops the stem, and the other the first leaf. 

 It is to be observed that in this first differentiation of body regions the 

 root is omitted, but it develops later from the tissue produced by the 

 leaf quadrant (fig. 294). The foot is a structure of the sporophyte 

 found among the bryophytes, among which the sporophyte is dependent 

 on the gametophyte through life. The suspensor is a new organ of the 



