1913-] STEVENSON— FORMATION OF COAL BEDS. 145 



abstract of his preliminary announcement has appeared. The 

 cannels studied by him are composed almost wholly of spore-exines 

 with resins and cuticles in limited quantity. The so-called binding 

 material in the intestices is distinctly of two substances, one, more 

 or less homogeneous and colloidal ; the other, more or less granular, 

 the fragmentary residue of spore-exines. He rejects the algal 

 theory of Bertrand and Renault as well as the sapropelic theory of 

 Potonie, both being undemonstrable. The so-called alg?e are not 

 algae, all forms but one having been proved to be exines of spores, 

 either of Pteridophytes or Cycadofilicates or of both. A gelosic 

 substance such as is called for by the theory is wholly absent. 



The exact nature of these bodies, though of extreme interest 

 from the botanist's standpoint, is of subordinate interest here. The 

 important fact seems to be that while these bodies are compara- 

 tively rare in ordinary coals, they are predominating constituents of 

 cannel and boghead, thus indicating a different mode of formation. 

 One must bear in mind also, that animal remains are present abun- 

 dantly in many cannels. 



The brown fundamental matter of the cannels and bogheads is 

 apparently the same as that which forms the basis of ordinary coal, 

 and it is supposed by Bertrand and Renault to be a precipitate from 

 the brown waters of swamp-pools, the precipitant being lime. Such 

 brown waters are widely distributed especially in tropical regions 

 Samples of such water, obtained by Marcano in South America, 

 were studied by Muntz^'*- who discovered only a trace of lime in the 

 dark water, which contains 0.028 gramme of organic matter per 

 liter, yet has an acid reaction. The colorless waters are distinctly 

 hard. The authors conclude that the acids were preserved in spite 

 of aeration, because nitrification and consequent oxidation could not 

 take place. When mingled with hard waters, the acids combine 

 with the lime, nitrification begins and destruction of carbonaceous 

 matter proceeds rapidly under influence of high temperature. The 

 quantity of organic acids is small, even when the color of the water 



"^ A. Muntz and V. Marcano, " Sur les eaux noires des regions equa- 

 toriales," C. R., Vol. 107, 1888, pp. 908, 909. 



PROC. AMER. PHIL. SOC. , LII. 2o8 J, PRINTED MAY l6, I9I3. 



