328 Dr. J. W. Dawson on Spore-cases in Coals. 



cellulose (C.^^H^aO^^), and represent cork and Lycopodium as 

 containing 24 equivalents of carbon. For comparison, I give 

 the composition of specimens of peat, brown coal, lignite, and 

 bituminous coal*. 



Cellulose C,,H.,o 0,3 



Cork ^.^..-h^.i, 



Lycopodium C,,Hj,ji,N0,y'5^^ 



Peat (Vaux) C^H^.tI^O^, 



Brown coal (SchriJtter) C.^^Hj^-j^Ojg^ 



Lignite (Vaux) C^.H^j^O.^iy 



Bituminous coal (Regnault) C^jH^^ ^^y^ 



" It will be seen from this comparison that, in ultimate 

 composition, cork and Lycopodium are nearer to lignite than to 

 woody fibre, and may be converted into coal with far less loss 

 of carbon and hydrogen than the latter. They, in fact, ap- 

 proach closer in com])osition to resins and fats than to wood, 

 and, moreover, like those substances, repel water, with which 

 they are not easily moistened, and thus are able to resist 

 those atmospheric influences which effect the decay of woody 

 tissue." 



I would add to this only one further consideration. The 

 nitrogen present in the Lycopodium-s^oxQ.B, no doubt, belongs 

 to the protoplasm contained in them, a substance which Avould 

 soon perish by decay ; and, subtracting this, the cell-walls of 

 the spores and the walls of the spore-cases would be most 

 suitable material for the production of bituminous coal. But 

 this suitableness they share with the epidermal tissue of the 

 scales of strobiles, and of the stems and leaves of ferns and 

 Lycopods, and, above all, with the thick corky envelope of the 

 stems of SigiUarke and similar trees, Avhich, as I have else- 

 where shownf, from its condition in the prostrate and erect 

 trunks contained in the beds associated with coal, must have 

 been highly carbonaceous and extremely enduring and im- 

 permeable to water. In short, if, instead of '' spore-cases," 

 we read " epidermal tissues in general, including spore-cases," 

 all that Huxley has affirmed will be strictly and literally true, 

 and in accordance with the chemical composition, microscopical 

 characters, and mode of occurrence of coal. It will also be in 

 accordance with the following statement, which I may be 

 pardoned for quoting from my paper on the " Structures in 

 Coal," published in 1859 :— 



" A single trunk of Siyillaria in an erect forest presents an 



* Canadian Naturalist, vi. 253. 



t "Vegetable Structures in Coal," Jdurn. Geol. Soc. xv. G2(> ; "Con- 

 ditions of Accumulation of Coal," ib. xxii. 95 ; Acadian Geology, 197, 4r»4. 



