264 DEVELOPMENT OF ANTHOCEROS 



termed the perianth (Fig. 197, C), assumes very characteristic 

 forms in the different genera and is generally associated with 

 modified leaves, the involucre. The gametospore develops after 

 the manner noted in Marchantia, forming a capsule with elaters, 

 but its stalk or seta reaches much larger dimensions, owing 

 doubtless to the well-developed foot which penetrates the thallus 

 and absorbs foods, thus making possible a larger sporophyte 

 (Fig. 197, E). When the spores have been matured the seta 

 rapidly elongates to several times its original length, rupturing 

 the archegonium and lifting the capsule high in the air (Figs. 

 196; 197, A). The capsule usually breaks open into four valves 

 which are hygroscopic, closing over the spores in damp weather 

 and opening in dry weather to expose them to the wind. These 

 spores germinate and begin the life history of a new gam- 

 etophyte. As in some of the Marchantiales a filamentous algal- 

 like growth is first formed by the germinating spore before the 

 characteristic plant is reproduced. 



1 06. Order c. Anthocerotales or Horned Liverworts. This 

 small group of three genera is the most interesting of all the 



FIG. 198. One of the Anthocerotales, Anthoceros, bearing four pod- 

 shaped sporophytes, s. The one on the right, /, has opened at the top and 

 is discharging the spores, but elongation and the formation of spores con- 

 tinues below owing to its basal growth. 



hepatics because it presents features that are suggestive of the 

 algae and also of a relationship with the mosses and ferns. 



