But to whatever cause the paucity of lichenists, both in our own and other countries, is to be attributed, it certainly does not originate in any difficulty connected with their collection and preservation. In fact, there is no other class of plants, where these, and more especially the latter, can be so easily effected, at a little expenditure of time and trouble. A few simple directions are, therefore, all that are necessary to be given on these points. As to the collecting of lichens, it has already been intimated that they are almost universally distributed, though of course in this respect subject to the same laws as the higher orders of vegetation. In our own country we have now a list of about eight hundred species, constituting by far the greater proportion of the Lichen Flora of Europe. In most parts of Great Britain and Ireland, a very fair number of these may readily be gathered, capable, as they are, of existing in almost every situation where they can derive requisite nourishment from the atmosphere. On the rocks and boulders of the seashore and the mountain-side, on the trunks and branches of trees in woods and forests, on peaty soil of bare moorlands, and on stone fences in upland tracts, nay, even on old pales and walls in suburban districts, a goodly harvest may generally be reaped. Few localities indeed there are, within the area of these islands (London and its environs, where the atmosphere is so impregnated with smoke, being the chief exception), in which the lichenist will find his occupation gone. True, it is only in some more favoured tracts, chiefly maritime and montane, that he can expect to meet with many of our rarer species; but even in most lowland districts, especially such as are well wooded, he may, with profit, pursue his researches, and collect various of the more common species. These will just be as useful in making him acquainted with the structure and physiology of lichens as though he had gathered the rarest that grow on Ben Lawers or by Killarney's lake. The apparatus requisite for collecting is neither complicated nor expensive.