CHAPTER V 



THE AECHEGONIATBS : I. BEYOPHYTES — LIVERWORTS 

 AND MOSSES 



All the plants we have studied up to the present are 

 classed as Thallophytes, a miscellaneous assortment of 

 forms which may be roughly characterized as showing 

 no distinction between stem and leaves; this definition, 

 however, does not hold good in every case. As it is not 

 our purpose in this book to discuss nice distinctions, we 

 deem it sufficient to state that all plants lower in organi- 

 zation than the Liverworts and Mosses are considered to 

 be Thallophytes. 



The Archegoniates (Gr. arcM, beginning; qone, genera- 

 tion, seed) include the Liverworts, Mosses, Ferns, Horse- 

 tails, and Club-mosses, all of which display a marked 

 similarity in the origin and structure of the female 

 reproductive organ — the archegonium. All plants in 

 this division show a marked alternation of generations. 

 The sexual generation is the gametophyte (Gr. gamos, 

 marriage; phyton, plant); it bears the archegonia (female 

 organs) and the aniheridia (male organs). Each arche- 

 gonium contains an egg-cell, which, after fertilization by 

 a spermatozoid, liberated from an antheridium, becomes 

 an embryo. The asexual generation develops from the 

 embryo; it is termed the sporophyte (Gr. sporos, seed; 

 and phyton) ; it is found attached to and dependent upon 



120 



