102 CRITIQUES AND ADDRESSES. [v. 



resinous matter, that a pincli of Lycopodium powder, 

 thrown through the flame of a candle, burns with an in- 

 stantaneous flash, which has long done duty for lightning 

 on the stage. And the same character makes it a capital 

 coating for pills ; for the resinous powder prevents the 

 drug from being wetted by the saliva, and thus bars 

 the nauseous flavour from the sensitive papillae of the 

 tongue. 



But this resinous matter, which lies in the walls of 

 the spores arid sporangia, is a substance not easily altered 

 by air and water, and hence tends to preserve these 

 bodies, just as the bituminized cerecloth preserves an 

 Egyptian mummy ; while, on the other hand, the merely 

 woody stem and leaves tend to rot, as fast as the wood 

 of the mummy's coffin has rotted. Thus the mixed 

 heap of spores, leaves, and stems in the coal-forest would 

 be persistently searched by the long- continued action of 

 air and rain ; the leaves and stems would gradually be 

 reduced to little but their carbon, or, in other words, to 

 the condition of mineral charcoal in which we find them ; 

 while the spores and sporangia remained as a compara- 

 tively unaltered and compact residuum. 



There is, indeed, tolerably clear evidence that the coal 

 must, under some circumstances, have been converted 

 into a substance hard enough to be rolled into pebbles, 

 while it yet lay at the surface of the earth ; for in some 

 seams of coal, the courses of rivulets, which must have 

 been living water, while the stratum in which their 

 remains are found was still at the surface, have been 

 observed to contain rolled pebbles of the very coal 

 through which the stream has cut its way. 



The structural facts are such as to leave no alternative 

 but to adopt the view of the origin of such coal as I have 

 described, which has just been stated ; but, happily, the 

 process is not without analogy at the present clay. I 



