+- 1 



PART II 

 ARCHEGONIATAE. 



Plants consisting cither of a thallus only, as some 

 liverworts and primitive mosses, or provided with stems 

 and leaves. The latter are either constructed of cells 

 only, as in the bryophytes, or provided with true vessels 

 and vascular tissues, as in the pteridophytes. 



The distinction of this group as a whole from the 

 thallophytes is in the mode of reproduction. There are 

 two regularly alternating generations, viz. a sexual and 

 an asexual one. The sexual generation, termed the 

 gametophyte, originates from the spore and produces two 

 kinds of sexual organs, viz. antheridia ( r ) and archegonia 

 ($) [Fig. 46]. The archegonium contains the oosphere 

 (egg-cell), which after fertilisation develops into the embryo 

 (the asexual generation). This is of a very different form 

 in the two sections of the group, but in both it produces 

 the spores by an asexual process, hence it is termed the 

 sporophyte. With the germination of the spore recom- 

 mences the cycle of life. 



While in the structure of their vegetative parts the 

 bryophytes resemble the thallophytes to some extent, the 

 pteridophytes do not materially differ from the flowering 

 plants in this respect. On the other hand their mode of 

 reproduction, while showing the two classes to be nearly 

 allied, separates them well from the lower plants on the 

 one hand and from the flowering plants on the other, 

 although there exist a few connecting links in both 

 directions. 



Division XII. Bryophyta. The gametophyte (the moss- 

 plant) mostly with stems and leaves, but without 

 vascular tissue; the sporophyte, a mostly stalked, 

 capsule-like body (moss capsule). 



Division XIII. Pteridophyta. The gametophyte small, 

 thalloid ; the sporophyte (the fern etc.) with true 

 roots, stems and leaves, all possessing vascular tissue. 



