THE PTERIDOPHYTES 



285 



365. Discussion. — The life history of a fern differs in a 

 striking way from that of a liverwort or moss. Ascending 



,..-A-n-- 

 "At- 



Spore. 

 Sporongtuw 



Fig. 207. Diagram of Life History of a Fern. 

 An, antheridium ; Ar, archegoniiun; s, sperm; e, egg-cell; e', egg. 



from the lower forms of plant life to the higher ones, it is 

 only when the ferns are reached that alternation of genera- 

 tions is shown in its most complete form. Jij this term a 



Pig. 208. Illustrated Life History of a Fern. 

 (The young fern-plant is Onoclea, Fig. 209.) 



process of reproduction is meant in which the offspring 

 resemble closely not the parent but the grandparent, as 



