'fif VEGETABLE SUBSTANCES. 



seed-vessels, shew that' they belong to the same 

 species. 



One of the most sinfi^ulai- changes to which any 

 country can be subjected, is that which arises from 

 the formation of extensive masses of peat-earth. 

 They are common in most of the colder parts of the 

 world ; and are known in Ireland (where they occupy 

 nearly one-tenth of the surface) by the name of bogs, 

 and in Scotland by the name o( peat-mosses. These 

 accumulations of a peculiar vegetable matter are a 

 sort of natural chronicle of the countries in which 

 they are found. In the northern parts of the island 

 of Great Britain, and in many places of Ireland, 

 especially in the central parts, between the Irish Sea 

 and the Shannon, they point out that the soil and 

 climate were once far superior to what the country 

 now, in those situations, enjoys. 



The era of the first commencement of these bogs 

 is not known ; but as in many of them, both in 

 Ireland and Scotland, are found the horns and 

 skulls of animals of which no live specimens now 

 exist in the country, and have not been since 

 the commencement of recorded history, their origin 

 must be referred to very remote periods. Not- 

 withstanding this, the formation of a peat-bog, 

 under favourable circumstances, does not appear to 

 be a very lengthened process ; for George Earl of 

 Cromarty mentions (Philosophical Transactions, No. 

 330) that near Loch Broaw, on the west of Ross- 

 shire, a considerable portion of ground had, between 

 the years 1651 and 1699, been changed from a forest 

 of barked and leafless pines, to a peat-moss or bog, 

 in which the people were cutting turf for fuel. 



The process, according to the Earl's description, 

 which has been verified by the observations of others, 

 is this : — The pines, after ha^ng stood for some time 

 deprived of their bark, and bleaching in the mins, 



