MOSSES. 



205 



The little group of Hepaticce or Liverworts, which is 

 intermediate between Lichens and Mosses, presents nume- 

 rous objects of interest for the microscopist. These 

 plants are produced by dust-like grains called spores, and 

 minute cellular nodules called gemmae or buds. The 

 gemmae of Marchantia polymorpliia are produced in 

 elegant membranous cups, with a toothed margin growing 

 on the upper surface of the frond, especially in very damp 

 court yards between the stones, or near running water, 

 where its lobed fronds are found covering extensive 

 surfaces of moist soil. At the period of fructification, 

 these fronds send up stalks, which carry at their summit 

 round shield-like or radiating discs. Besides which, it 

 generally bears upon its surface a number of little open 

 basket-shaped " conceptacles " which are borne upon the 

 surface of the frond, as in fig. 114, and may be found 

 in all stages of develop- 

 ment. When mature 

 it contains a number of 

 little green round or ob- 

 long discs, each com- 

 posed of two or more 

 layers of cells; the wall 

 is surmounted by a glis- 

 tening fringe of teeth, 

 whose edges are them- 

 selves regularly fringed 

 with minute outgrowths. 



The CUp Seems tO be 



f^-.,-* *^A "U A 1 chantia poly morphia, expanding and rising 



formed by a develop- from the surf ace of a frond. 



rnent of the superior 



epidermis, which is raised up and finally bursts and 



spreads out, laying bare the seeds. The development of 



this structure presents much analogy to that of the sori of 



Ferns. 



Mwcacece, mosses, are another low form of vegetable 

 life, Linnseus called them servi, servants, or workmen, 

 as they seem to labour to produce vegetation in newly- 

 formed countries, where soil is not yet formed. They also 

 fill and consolidate bogs, and form rich mould for the 

 growth of larger plants, which they protect from the 



. Gemmiparous Conceptacle of Mar- 



