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A TEXTBOOK OF THEORETICAL BOTANY 



The antheridia are very small, and arise in terminal clusters on the side 

 branches, frequently near the female organs. The side branches produce 

 short antheridial branchlets, on each of which four antheridia are borne. 

 Each antheridium liberates a single naked, non-motile, spherical body which 

 is called a spermatium. 



The carpogonium develops on a specialized lateral branch, which is called 

 the procarp (Fig. 140). It arises near the base of a vegetative branch, and 



CARPOSPORE 



TRICHOGYNE 



SPERMATIUM 



GONIMOBLAST 

 FILAMENT 



Fk;. 140. — Batrachospermuni moniliforme. A and B, Development of carpogonium. C, 

 Fertilization stage. D, Germination of zygote. E, Beginning of gonimoblast filaments. 

 F, Carpospores forming on gonimoblast filaments. {After Kylin.) 



generally consists of a filament of four cells. The terminal cell becomes the 

 carpogonium and soon develops a swelling at its anterior end, which elongates 

 very considerably and forms a filamentous structure known as the trichogyne. 

 In some types of Red Algae the nucleus of the carpogonium divides at this 

 stage, and one of the daughter nuclei migrates into the trichogyne, but this 

 does not normally occur in Batrachospermuni. Meanwhile the carpogonium 

 enlarges, the chromatophore which it originally contained disappears and 

 the female nucleus sinks to the base of the cell. 



Spermatia which have been liberated from the antheridia are carried 

 by the water to the trichogyne, to which they adhere. The wall of the 

 trichogyne breaks down at the point of contact with the spermatium, and the 

 nucleus of the spermatium migrates into it. It then passes down the 

 trichogyne and fuses with the female nucleus in the carpogonium, after which 

 the basal part of the carpogonium is isolated by a cross wall and forms the 

 zygote. The zygote nucleus divides into two, one nucleus then migrates into 

 a lateral protrusion which develops in the side of the zygote, and is cut ofl^ by 

 a wall. The remaining nucleus then also divides and a second lateral pro- 

 tuberance is formed into which one of the daughter nuclei migrates. From 

 these lateral cells, cut off from the zygote, filaments of cells develop which 

 are called gonimoblasts. They branch repeatedly and small spores termed 

 carpospores are formed at their ends. 



