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TEXTBOOK OF BOTANY 



excepting that a small part just back of the growing point 

 (the notch) is several cells thick. This thicker part is not 

 found in smaller and younger plants, but only in those that 

 have been growing for some time. From the lower surface 

 of the plant rhizoids grow downward into the soil, serving 

 the same purposes as the rhizoids of a moss. Each rhizoid 

 is a long cell. The rhizoids are borne mostly on the older 

 part of the plant — that is, on the narrower portion farthest 

 from the growing point. 



The sexual plant of the fern, like that of the moss, bears 

 sex organs. Both archegones and antherids are borne on 

 the same plant; as a rule they grow, like the rhizoids, from the 

 lower surface. Most of the antherids are formed on the older 

 parts of the plant — in the same general region, therefore, 

 as the rhizoids. But antherids sometimes appear also on 

 the younger portions of the plant. The archegones are 

 borne, in smaller numbers than the antherids, on the thicker 

 part of the plant near the growing point. They develop in 

 general later than the antherids ; consequently one is likely 

 to find many young plants, as well as older ones whose growth 

 was checked in some way while they were still small, which 

 bear antherids but no archegones. 



131. Sex Organs, Gametes, and Fertilization. — The archegone of 

 a fern (Fig. 56, A) is shorter than that of a moss. It has no stalk 

 and its base is embedded, as though it had been pressed down among 

 the vegetative cells. The neck is short and is curved backward toward 



the part of the plant 

 where antherids are 

 borne. The antherid 

 of a fern (Fig. 56, B) 

 is also smaller and 

 simpler than that of 

 a moss, and it pro- 

 duces a much smaller 

 number of anthero- 

 zoids (Pig. 57). Al- 

 though both kinds of 



Fig. 56. 



- Sex organs of a fern : 

 B, an antherid. 



an archegone ; 



