308 



THE MICROSCOPE. 



The little group of Ilepaticce or Liverworts, which if 

 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 gemmce or buds. The 

 gemmae of Marchantia polymorphic^ 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. 162, 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 

 formed by a develop- 

 ment 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. 



Muscacece, Mosses, are an interesting form of vegetable 

 life, Linnaeus 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 



Fig. l62.Gemmiparous Conceptacle of Mar- 

 chantia polymorphia, expanding and rising 

 from the surface of a frond. 



