178 A TEXTBOOK OF THEORETICAL BOTANY 



The spermatium has a thin cellulose wall and may therefore be regarded 

 as an antheridium containing one antherozoid, the whole being shed at the 

 same time. 



ANTHERIDIUM 



Fig. 170. — Corallino officinalis. Formation and liberation of antheridia. A, 

 Antheridia attached to mother cell. B, Free antheridia. C, Mother cells with 

 attached antheridia and one in process of liberation. {After Sumeson.) 



The Carpogonium 



Each disc cell produces a separate procarp branch. The cell first divides 

 into two to form an upper cell, which becomes the auxiliary cell, and a lower 

 one, which is the stalk cell. Then the auxiliary cell gives rise to two sister 

 cells, which are produced side by side (Fig. 171). They are not, however, 

 produced simultaneously, and one has enlarged considerably before the 

 other is produced. The older one enlarges and becomes the carpogonium, 

 whose distal end becomes very greatly elongated to form a trichogyne, which 

 protrudes through the ostiole of the conceptacle. Meanwhile the nucleus of 

 this cell has divided into two. One remains at the base in the carpogonium, 

 while the other migrates into the trichogyne. The sister cell soon ceases to 

 grow and remains as a small non-functional structure beside the carpogonium. 

 Since all the disc cells within the conceptacle form procarp branches it follows 

 that a large number of separate carpogonia will be formed and that many 

 trichogynes will protrude through the ostiole (Fig. 172). 



In this position they are exposed to the sea water and readily catch any 

 spermatia which come into contact with them. Though the point has not 

 yet been definitely proved it is assumed that after liberation from the male 

 conceptacle the spermatium loses its wall, and at the time it comes into 

 contact with the trichogyne it is a naked spherical protoplasmic mass. The 

 nucleus in the trichogyne disorganizes, and the male nucleus migrates down 

 the trichogyne and fuses with the carpogonial nucleus. 



