BOTANY. 351 



the subject, and many able reports made on it, strange to say, no one has 

 yet given any intelligible account of the species of plants which enter princi- 

 pally into the formation of the turf-bogs of Ireland, although so large a 

 portion of the surface of the country is covered with them, and bog-labor 

 constitutes no inconsiderable item., of productive economy in Ireland. By 

 far the greatest portion of the bogs in Ireland consists of the kind called red 

 bog, which varies in depth from ten to forty feet, or even more. This variety 

 is the least valuable for fuel, owing to its soft fibrous consistency. It is sup- 

 posed to have been formed on the sites of extensive ancient lakes, or very 

 Avet morasses, which may be inferred from the small quantity of wood found 

 mixed up with it; besides the roots and trunks of trees being mostly found 

 near the edges of the bog, the portions towards the centre being composed 

 of nearly a uniform mass of the debris of the list of plants mentioned. It 

 was further stated, that although Sphagnums constitute a large portion of 

 this substance, without the aid of the roots and branches of phanerogamic 

 plants to form a kind of framework to bear up the cryptogamic species, the 

 formation of bog could not go on at nearly so quick a ratio as it does. In 

 the absence of all trustworthy experiments on the growth of bog, the rate 

 of increase could not be well ascertained, but holes out of which turf had 

 been cut had been observed filled up with soft vegetable matter, to the depth 

 of one foot in five years, which if supposed to be ultimately compressed 

 into one-fourth part that bulk, after being solidified, as near an approach 

 as can be made to the rate of increase of bog at the present day might prob- 

 ably be reckoned on. In limestone districts, where the larger species of 

 Chara abound, whose stems and branches are always thickly incrusted with 

 calcareous substances, the deposition of matter takes place faster than it 

 does where those plants are not so common. The debris resulting from 

 Chara liispida alone, where it grows freely, will soon fill up a shallow pool, 

 so that plants higher in the scale of vegetation can grow on it. According 

 to the report of the commissioners appointed to report on the nature and 

 extent of the Irish bogs, upwards of a million of English acres are covered 

 with red and brown bog, more than two third parts of which are westward of 

 the river Shannon. The variety called black or turbary bog was next consid- 

 ered in detail, which is the most valuable for fuel, owing to the great quan- 

 tity of woody matter it contains. This variety is supposed to have been 

 formed on the sites of ancient forests, as is evident from the large quantities 

 of prostrate trunks of trees and their roots, frequently in situ, which are 

 found in it. The kinds consist chiefly of Pinus sylvestris, Qnerciis robtir, 

 Betula alba, and Alnus glutinosa, though large quantities of yew, Taxus bac- 

 cata, and some mountain ash, are also found in particular districts. The 

 roots of the oaks are generally nearest the margins of the bogs, resting on 

 the clay or marl bottoms, while the Scotch firs occur further towards the 

 centre, and rest on several feet of peat, thus showing that a considerable 

 accumulation of that substance must have taken place before they vegetated 

 on it. These roots are frequently found one above the other, where they 

 have grown, which has led some to suppose there have been several consecu- 

 tive and distinct epochs of growth, and that some species of the trees which 

 formed them are not now natives of Ireland. This hypothesis was not 

 considered correct, but rather, that by the gradual growth of the bog, matter 

 accumulated and covered the first tier of roots, and the seeds of contiguous 

 trees on falling and vegetating above them grew, and formed in their turn 

 another tier, and so on up to the present surface; as a few of the trees of 



