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A TEXTBOOK OF THEORETICAL BOTANY 



The Antheridium 



The antheridia are spindle-shaped bodies, somewhat rounded at both 

 ends, and supported on short stalks. A single receptacle bears from twenty 

 to fifty (Fig. 403). The antheridium arises from a superficial cell of the 



Involucral bract — 



Paraphyses 



Antheridium - 



Fig. 403. — Milium honnim. Vertical section through 

 antheridial head showing broadened apex of 

 stem and elongated antheridia surrounded by 

 involucral bracts. 



receptacle which divides into two, the lower cell forming the stalk, and the 

 upper the antheridium. The upper cell then divides so as to produce an 

 apical cell, and from it about seven segments are cut oflF on each side. Walls 

 are then laid down parallel to the surface of the antheridium in such a way 

 that a single-layered wall is formed around it. From the central cells the 

 antherozoids are developed, and when mature they escape through an 

 opening at the apex of the antheridium (Fig. 404). 



The Archegonium 



The plants bearing the archegonia are generally considerably shorter than 

 those bearing the antheridia and are somewhat darker in colour. The leaves 

 at the apex close over the archegonia, protecting them during their develop- 

 ment (Fig. 405). The archegonia are borne in the axils of leaves in the 

 same way as the antheridia, but fewer archegonia are usually produced. The 

 development of the archegonium is initially similar to that of the antheridium. 



