66 STEVENSON— FORMATION OF COAL BEDS. [April 21. 



It is possible that spores may have been there and that they may 

 have been decomposed, but spores are much more resistant than 

 is woody materiah The main division has a great accumulation of 

 spores but also a fair proportion of the " hydrocarbon." He con- 

 cludes that some coals are made up practically of spores, others are 

 not; the differences in benches of a coal bed are of this character. 

 Harker, reasoning from the ornamentation of the spores, suggested 

 that they may have come from a plant related somewhat to Isoetus. 



In the discussion of this paper, Carruthers took exception to con- 

 clusions based on markings seen on spores. He knew of no reason 

 for referring those spores to Isoetus or any other form of sub- 

 meged vegetation. Spores in coal were discovered first by Morris ; 

 they are associated with Sigillaria and Lepidodendron; the coal was 

 the soil for the vegetation, penetrated by Stigniaria roots of the 

 plants. A Sigillaria stem, at the Leeds museum, filled with white 

 sand, penetrated far into the coal in which it grew. Coal seams are 

 remains of forests which grew on swampy ground. The macro- 

 spores were not composed originally of brown substance, they are 

 merely filled with it. 



E. T. Newton stated that some coals are certainly made up of 

 macrospores and microspores. Dull coal contains spotted tissue ; in- 

 termediate coal contains both forms of spores ; bright coal is a 

 brown substance, usually structureless, but in one case, known to 

 him, it consists wholly of spores. 



Dawkins had never found sporangia in coal though both macro- 

 spores and microspores arc abundant. Coal consists of carbon and 

 resin, the latter giving the property of blazing, which Huxley would 

 attribute chiefly to the spores. With this conclusion, Dawkins 

 agrees only in part. The carbon comes from decomposition of 

 woody portions, but the resin from cell concretions in the living 

 plant. Carboniferous forests grew on level alluvial tracts but little 

 above the water level. 



Dawkins,"^ discussing the geographical conditions in Great Britain 



during Carboniferous time described the mode in which the coal beds 



accumulated. 



""W. B. Dawkins, "On the Geography of Britain in the Carboniferous 

 Period," Trans. Manchester Gcol Soc, Vol XIX., 1887, pp. 45-47. 



66 



