164 A COtfTEIBTJTION TO, ETC. 



there is evidently much obscurity, and although as in the case of 

 ferns and mosses, the spores of lichens seem to be wafted by the 

 breeze, or conveyed by falling rain, and afford " one means of 

 that gradual but never-ceasing disintegration or decay, which is 

 wearing down the densest and loftiest pinnacles of the earth ;" 

 yet the mode of their fructification is but imperfectly understood. 

 Without offering any speculative opinion, therefore, on the fact 

 that certain conditions only seem necessary for the production of 

 many cryptogamous plants, I shall endeavour to enumerate the 

 species of lichens which occur in this neighbourhood, and to 

 point out some of their probable uses in the economy of nature. 



The word Lichen is of Greek origin, and means a wart, and it 

 seems to have been applied to this family of plants, from a fancied 

 resemblance between warts, and the fructification of some lichens. 

 In common conversation, many of the lichens, especially 

 JTsnea larlata, (the " bearded Moss" of the poets), and 

 Cladonia bellidiflora, (the " Bed-cupped moss" of Mrs. Hemans 

 and others) are termed mosses, and, therefore, it may be desir- 

 able to state, that, according to the definition of a late writer, 

 " Lichens are aerial plants with leaves and stem combined into 

 a visible above-ground thallus, which either spreads horizontally 

 in the form of a lobed, irregular crust or plate, or rises erect 

 with irregular, unsymmetrical branches, the reproductive organs 

 being embedded in external disks or shields." With respect to 

 these organs, however, there is much difficulty, and the nature 

 and functions of what lichenologists call sperniatia (that is 

 minute acicular, or linear bodies, straight or curved, and of 

 various forms) is wholly unknown. These spermatia are developed 

 long before the spores, and according to late writers, they bear 

 some analogy to the antherozoids of the genus Ghara. Very 

 high powers of the miscroscope have been applied to these bodies j 

 but owing to their extreme tenuity, they have hitherto baffled ex- 

 amination. It would occupy too much space to pursue this sub- 

 ject any further, nor indeed would it interest the general reader ; 

 but I may remark that in the vegetable, as well as in the animal 

 kingdom, there are many mysteries to be solved in reference to 

 the lower forms, especially as regards their varying modes of 

 reproduction. How the sterile moss, or the sterile lichen (no 

 organs of fructification being apparent) spreads over the barren 



