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No plants can be so easily collected and preserved as lichens, requir- 

 ing merely to be cleaned, dried, pulverized, and packed ; and, if their 

 bulk be an objection to transport, their whole colorific matter may be 

 collected in the way I have already mentioned. Ascending to the 

 verge of eternal snows, and descending to the ocean-level, with a 

 geographical diffusion that is coextensive with the surface of our 

 earth, it is difficult to say where lichens shall not be found. There 

 are myriads of small, rocky islets in the boundless ocean, and there 

 are thousands of miles of barren, rocky coast and sterile mountain- 

 range in every part of the world, which, though at present unfit to 

 bear any of the higher members of the vegetable kingdom, yet are 

 carpeted and adorned with a rich covering of lichens, and of those 

 very species, too, which I have already spoken of as most prolific in 

 colorific materials. I sincerely believe, therefore, that a more general 

 attention to the very simple tests just enumerated, would ultimately re- 

 sult in a greatly more extended use of the lichens as dye-agents. What 

 renders it very probable that efforts in this direction are likely to meet 

 with success, is the great similarity of species found all over the world. 

 It has been repeatedly noticed that the European species, which, of 

 course, are best known, differ little from those of North America. 

 Dr. Robert Brown remarked the same fact with regard to New- Hol- 

 land species ; and Humboldt also recognized the similarity in natives 

 of the South-American Andes. Of a large collection made by Pro- 

 fessor Royle, in the Himalayas, Don pronounced almost every one to 

 be identical with European species. From examining the raw vege- 

 table products sent by different countries to the Great Exhibition of 

 1851, 1 am satisfied that even now there are many fields open for the 

 establishment of an export trade in Roccellas and other so-called 

 orchella-weeds. I there saw specimens of good dye-lichens from 

 almost every part of the world, including our own young colonies ; 

 and as a single instance of their probable value I may introduce here 

 the copy of a note appended to a specimen of orchella-weed, from the 

 Island of Socotra, contained in the Indian collection of that Exhibi- 

 tion : — ' Ahundavt, but unknown as an article of use or commerce. 

 Also abundant on the hills around (Aden), and might be made an 

 article of trade. Aden, April, 1847.' Roccellas from this source are 

 estimated as worth £190 to X380 per ton. 1 believe that a similar 

 statement might be made with regard to the countless islands of the 

 broad Atlantic and Pacific, which may at some future period, perhaps 

 not far distant, be found to be rich depots of orchella-weeds, just as 

 some of them are at present rich fields of guano ; and may, as such, 



