234 THE GROWTH OF COAL 



South Joggins, and of the great thirty feet seam of the Picton 

 coal series, whose innumerable laminae have all been subjected 

 to careful scrutiny, and have shown unequivocal evidence of 

 land surfaces accompanying the deposition of the coal. Micro- 

 scopical examination has proved that these coals are composed 

 of the materials of the same trees whose roots are found in the 

 underclays, and their stems and leaves in the roof shales ; that 

 much of the material of the coal has been partially subjected to 

 subaerial decay at the time of its accumulation ; and that in 

 this, ordinary coal differs from bituminous shale, earthy bit- 

 umen and some kinds of cannel, which have been formed under 

 water; that the matter remaining as coal consists almost entirely 

 of epidermal tissues, which being suberose or corky in char- 

 acter are highly carbonaceous, very durable and impermeable 

 by water, and are, hence, the best fitted for the production of 

 pure coal ; and finally, that the vegetation and the climatal and 

 geographical features of the coal period were eminently fitted 

 to produce in the vast swamps of that period precisely the 

 effects observed. All these points and many others have been 

 thoroughly worked out for both European and American coal 

 fields, and seemed to leave no doubt on the subject. But 

 several years ago certain microscopists observed in slices of 

 coal, thin layers full of spore cases, a not unusual circumstance, 

 since these were shed in vast abundance by the trees of the 

 coal forests, and because they contain suberose matter of the 

 same character with epidermal tissues generally. Immediately 

 we were informed that all coal consists of spores, and this being 

 at once accepted by the unthinking, the results of the labours 

 of many years are thrown aside in favour of this crude and 

 partial theory. A little later, a German microscopist has 

 thought proper to describe coal as made up of minute algae, and 

 tries to reconcile this view with the appearances, devising at the 

 same time a new and formidable nomenclature of generic and 

 specific names, which would seem largely to represent mere 



