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BOTANY: PRINCIPLES AND PROBLEMS 



wood but also inside, next the pith, and thus completely surrounds 

 the wood. The cells of both wood and bast are somewhat less 



Fig. 202. — The gametophyte of a fern. View of the under surface, which lies 

 next the surface of the ground. Here are borne the archegonia (near the notch) 

 and the antheridia (farther back, among the rhizoids). 



Fig. 203 — Sexual organs of a fern. A, section of archegonium just before 

 maturity. Within can be distinguished the large egg cell, below which are the 

 ventral canal cell and two neck-canal cells. In B, the archegonium is mature and 

 its neck has opened. The egg and ventral canal cells are evident, but the neck- 

 canal cells have broken down. C, section of antheridium, showing basal cell (1), 

 ring cell (2), and cap cell (3). D, one of the sperms, more highly enlarged. 



highly specialized than in the seed plants. Particularly in the 

 stouter-stemmed species, the fibro-vascular system sometimes 



