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Plant’ which is the result of the union of the 
sperm and egg-cell, and which, when it is adult, 
produces the asexual spores. The former is. 
known as the sexual generation, the latter as 
Fic. 5.—Young fern plant attached to Prothallus. 
Fl,=First frond ; FR.=First root; Rk.=Rhizoids of Prothallus. 
the asexual. Neither of these generations can 
be produced independently of the other ; there 
must be an interposition of the one generation 
between two of the other. The life-cycle of 
the fern thus. shows what is known as the 
2 
