CHAPTER VI 



THE AECHEGONIATES : II. PTERIDOPHYTES — EERNS, 

 HORSETAILS, AND CLUB-MOSSES 



The leading characters of the Archegoniates were 

 defined at the commencement of the last chapter, and 

 in our study of the Liverworts and Mosses (Bryophytes) 

 we saw that in their case the sporophyte is attached to 

 and dependent upon the gametophyte throughout its 

 life. In the Pteridophytes (literally, fern- or feather- 

 plants), the sporophyte is " the plant " as ordinarily 

 recognized. What is spoken of as " the plant " in the 

 Bryophytes is the gametophyte, or sexual generation — 

 the Liverwort thallus or the Moss-plant. The sexual 

 organs of the Bryophytes are borne on " the plant," but 

 in the Pteridophytes they occur on an inconspicuous 

 prothallus, which arises from the spore on germination. 

 It is called a ^xothallus to differentiate it from the proto- 

 nema of Mosses ; the latter is more or less, mostly more, 

 threadlike, while the former is thalloid; the prothallus 

 of the Perns and their allies carries the sexual organs, 

 whereas the protonema of the Mosses gives rise to buds 

 which grow into Moss-plants that bear the archegonia 

 and antheridia. The alternation of generations is dis- 

 tinctly marked in the Pteridophytes, but the sexual 

 generation, the gametophyte, is never conspicuous. The 

 prothallus does not attain great size ; in no instance does 



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