v.] ON THE FORMATION OF COAL. 97 



Lcpidodendroid trees of the coal : their steins and leaves 

 arc similar ; so are their cones ; and no less like are the 

 sporangia and spores ; while even in their size, th,e spores 

 of the Lepidodendron and those of the existing Lycopo- 

 dium, or club-moss, very closely approach one another. 



Thus, the singular conclusion is forced upon us, that 

 the greater and the smaller sacs of the " Better-Bed " 

 and other coals, in which the primitive structure is well 

 preserved, are simply the sporangia and spores of certain 

 plants, many of which were closely allied to the existing 

 club-mosses. And if, as I believe, it can be demonstrated 

 that ordinary coal is nothing but " saccular " coal which 

 has undergone a certain amount of that alteration which, 

 if continued, would convert it into anthracite ; then, the 

 conclusion is obvious, that the great mass of the coal 

 we burn is the result of the accumulation of the spores 

 and spore-cases of plants, other parts of which have 

 furnished the carbonized stems and the mineral char- 

 coal, or have left their impressions on the surfaces of 

 the layer. 



Of the multitudinous speculations which, at various 

 times, have been entertained respecting the origin and 

 mode of formation of coal, several appear to be nega- 

 tived, and put out of court, by the structural facts the 

 significance of which I have endeavoured to explain. 

 These facts, for example, do not permit us to suppose 

 that coal is an accumulation of peaty matter, as some 

 have held. 



Again, the late Professor Quekett was one of the first 

 observers who gave a correct description of what I have 

 termed the "saccular" structure of coal; and, rightly 

 perceiving that this structure was something quite dif- 

 ferent from that of any known plant, he imagined that 

 it proceeded from some extinct vegetable organism which 

 was peculiarly abundant amongst the coal-forming plants. 



