50 SURVEY OF THE REPRODUCTIVE PROCESS 



As reproductive organs, both Hepaticse and mosses bear, 

 on the same or on different plants, certain correlated struc- 

 tures, termed antheridia and pistilUdia, and performing the 

 same sexual functions as the anthers and pistils of the 

 higher plants. They are frequently surrounded by a leafy 

 sheath, or a circle of leaf-scales, termed \\\q perichwtium, and 

 are either immersed in the cellular tissue of the receptacle, 

 or attached to its surface, or raised on a peduncle. 



The antheridium is a small club-shaped process, which 

 contains in its distended extremity minute cellules, each 

 enclosing an actively moving filament or antherozoid. The 

 pistillidium, or archegoriium again, consists of cells built up 

 into a flask-shaped structure somewhat resembling the pistil 

 of a flower, with a dilatation like an ovaiy at its base, con- 

 taining a peculiar central corpuscule. Through the canal 

 in the apparent style some of the antherozoids seem to gain 

 access to the corpuscule, and the latter on fecundation de- 

 velopes, by endogenous formation, a whole mass of cells 

 which eventually assume, by a process of transformation, 

 in the course of growth, the form of the theca or capsule. 

 In mosses this organ, with its seta, calyptra, operculum, 

 and columella, has rather a complicated structure ; in 

 Hepatic?e it is simpler, but in all cases alike its internal 

 cellular tissue developes a mass of dust-like spores. In the 

 frondose Hepaticae the spores germinate at once into the 

 lobed expansion of gTeen parenchpna, constituting the 

 typical form of these plants, but in those species which have 

 a true axis, and in mosses, the germination first gives origin 

 to confervoid threads, which, after ramifying into a mass of 

 tangled filaments, termed the protonema,^ send up here and 

 there a leafy axis, bearing eventually like the original one 

 antheridia and archegonia. 



This development of the fecundated germ into the organ 



* Once ranked as an alga under the name of Bysms. 



