BRYOPHYTES 



291 



the body of the structure. The neck consists of a single row of 

 eight cells surrounded by a single layer of cells ; when the egg 

 cell is mature, the axial row of cells becomes liquefied. The 

 antheridial branch (Fig. 140, b) bears alobed, disk-shaped body 

 with flask-shaped cavities which open on the upper surface. 

 The antheridia are borne singly in these cavities and produce 

 great numbers of sperms which finally escape and swim in the 



Flo. 139. Cross-section of M. polymorplia showing structure. 



thin film of moisture over the surface of the plants. Some of 

 these sperms reach the archegonia, swim down the neck, and one 

 unites with the egg or oosphere (fertilization). 



The cell which is formed by the union of the two sex cells 

 or gametes is the fertilized egg and is the beginning of the next 

 or sporophyte generation. The young sporophyte develops into 

 foot, seta and capsule. The capsule bears spores and fiber-like, 

 spirally thickened cells known as elaters. When the spores are 

 mature, the elaters expand, bursting the capsule and scattering 

 the spores. 



The basal part of the archegonium persists as. a cup-shaped 

 structure and is known as the calyptra. The spores germinate 



