MOSSES. 



159 



of mosses, and is one way in which they are separated from the 

 leafy-stemmed liverworts, the latter never having a midrib. 



336. The fruiting moss plant. In fig. 197 is amoss plant "in 

 fruit," as we say. Above the leafy stem a slender stalk bears 



the capsule, ancl in this capsule are borne 

 the spores. The capsule then belongs to 

 the sporophyte phase of the moss plant, and 

 we should inquire whether the entire plant 

 as we see it here is the sporophyte, or 

 whether part of it is gametophyte. If 

 a part of it is gametophyte and a part 

 sporophyte, then where does the one end 

 and the other begin ? If we strip off the 

 leaves at the end of the leafy stem, and 

 make a longisection in the middle line, we 

 should find that the stalk which bears the 

 capsule is simply stuck into the end of the 



Fig. 197. 



Portion of moss plant of Mnium affine, showing two 

 sporogonia from one branch. Capsule at left has just shed 

 the cap or operculum ; capsule at right is shedding spores, 

 and the teeth are bristling at the mouth. Next to the right 

 is a young capsule with calyptra still attached ; next are 

 two spores enlarged. 



leafy stem, and is not organically connected with it. This is 

 the dividing line, then, between the gametophyte and the sporo- 

 phyte. We shall find that here the archegonium containing 



