LIVERWORTS AND MOSSES. 



59 



for these arc great on account of its rapid growth and the 

 supply required as reserve for 



each spore. The foot, being in 

 close contact with the tissue of 

 the gametophyte, acts as an 

 absorbing organ, receiving food 

 solutions from it. The sporo- 

 phyte thus lives, in part at least, 

 as a parasite upon the gameto- 

 phyte. 



In some mosses there is a ten- 

 dency to increase the nutritive 

 work of the sporophyte by de- 

 veloping at the top of the stalk, 

 below the spore-case, a mass of 

 green tissue. InBryumfyi, fig. 

 72) this gives the capsule a pear- 

 shape, while in Splachnum {B, 

 C, D, fig. 72) it is so far de- 

 veloped as to exceed the spo- 

 rangium. In some species it is 

 expanded into a miniature um- 

 brella which, one can imagine, 

 might readily become segmented 

 into leaves. 



The intimate attachment of sporophyte to gametophyte 

 continues throughout the life of the former. Sometimes the 

 gametophyte perishes at the close of the growing season, but 

 more commonly it is perennial, growing and branching at the 

 anterior end as the older posterior parts die away. 



Fig. 73.— Yonni; sporophyte of Phas- 

 i urn cuspidatum. c, columella ; f, 

 foot, embedded in gametophyte stem; 

 s, seta (cells not shown); s/>s, spo- 

 rangium ; s/>, spore-mother-cells. 

 Magnified 80 diara.— After Kienitz- 

 Ge*rloff. 



