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A TEXTBOOK OF THEORETICAL BOTANY 



up of a series of articulated, multifilamentous segments and are densely 

 encrusted with lime. The segments at the base of the main branches are 

 about as long as broad, but are narrower in the upper parts. 



The plants are dioecious, the male and female plants being morphologically 

 alike. As a result of fertilization a tetrasporic plant is developed which again 

 is identical in form with the sexual plants. The reproductive organs are 

 developed in conceptacles, those bearing the male organs being pear- 

 shaped, while those producing the female and the asexual reproductive organs 

 are both ovoid. 



Structure of the Thallus 



The structure of the vegetative thallus is very elaborate and is an example 

 of the fountain type of construction. The central part of the thallus is 



mf.^f^M 







V'^-'Htl^ .•'^■■ 



L"* **«*'^'»* %^» \l4^ *i^ iffSNij * *" * *' "s^i^' 



FiG. 168. — Corallinn officinalis. Structure of the joint 

 bet\\een two thallus segments. 



composed of parallel rows of very narrow elongated cells, with numerous 

 lateral branches composed of small cells which are compacted to form a 

 cortex. These cortical cells are filled with dense cytoplasm and chromo- 

 plasts, while the cells of the central region are only sparsely provided with 

 cytoplasm. 



The development of a new^ segment is brought about by the elongation 

 of the axial cells at the apex of an existing segment to form three outgrowths, 

 each consisting of a bundle of narrow cells similar to and continuous with 

 those of the central tissue. These elongated cells divide transversely, cutting 

 off a group of long basal cells which thicken up to form the joint between 



