70 APHORISMS AND REFLECTIONS 



found to be identical -with that deadly ' ' choke- 

 damp " by which the lives of those who descend into 

 old wells, or mines, or brewers' vats, are sometimes 

 suddenly ended ; and with the poisonous aeriform 

 fluid which is produced by the combustion of charcoal, 

 and now goes by the name of carbonic acid gas. 



During the same time it gradually became evident 

 that the presence of sugar was essential to the 

 production of alcohol and the evolution of carbonic 

 acid gas, which are the two great and conspicuous 

 products of fermentation. And finally, in 1787, the 

 Italian chemist, Fabroni, made the capital discovery 

 that the yeast ferment, the presence of which is 

 necessary to fermentation, is what he termed a 

 " vegeto-animal" substance ; that is, a body which 

 gives off ammoniacal salts when it is burned, and is, 

 in other ways, similar to the gluten of plants and 

 the albumen and casein of animals. 



The living club-mosses are, for the most part, 

 insignificant and creeping herbs, which, superficially, 

 very closely resemble true mosses, and none of them 

 reach more than two or three feet in height. But, 

 in their essential structure, they very closely resemble 

 the earliest Lepidodendroid trees of the coal : their 

 stems and leaves are similar ; so are their cones ; 

 and no less like are the sporangia and spores ; while 

 even in their size, the spores of the Lepidodendron and 

 those of the existing Lycopodium, 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 



