:^6o 



BOTANY OF THE LIVING PLANT 



classification of Mosses. The sexual organs are often protected by 

 specially developed " perichaetial" leaves, which give an almost 

 flower-like appearance [Polytrichiim). In some Mosses the antheridia 

 and archegonia are grouped together, as in Meesia (Fig. 302) ; but 

 commonly they are separate, either on distant branches of the same 

 plant (Funaria hygrometrica) , or on different plants [Polytrichum, 

 Buxbaumia). 



The analogy between the arrangement and distribution of the stamens and 

 carpels in the flowers of Angiosperms and the sexu 1 organs in the peri- 



FiG. 303. 

 i.-vi. Stages in development of the antheridium of Funaria hygrometrica, after 

 Campbell (x40o). vii. Spermatozoids of Funaria, after Campbell, and Sachs. 

 (x8oo). viii. Empty antheridium of Andreaea, with paraphysis, after Kiihn. 

 (XI35)- 



chaetia of Mosses is obvious. But it must always be remembered that the 

 two sides of this comparison are essentially different. The antheridia and 

 archegonia of Mosses are the real sexual organs borne by the gametophyte 

 and they contain the gametes ; the ovules and pollen-sacs of Angiosperms 

 are parts of the sporophyte, specialised so as to produce the highly modified 

 gametophytes, which in their turn produce the gametes. 



Both types of sexual organs project freely from the surface of the 

 plant. Each originates from a single cell, by a segmentation which 

 shows a continued apical sequence, and is quite distinct from thatseen in 

 the sexual organs of Pteridophytes. The antheridium (Fig. 303, i.-viii.) 



