i9:i.] STEVENSON— FORMATION OF COAL BEDS. 53 



substance originated, mainly, from marine plants of such peculiar 

 form that they cannot be assigned to any group of known types. 

 He created a new group for their reception, Protophytce, of which 

 he made seven divisions. Remains of land plants are of very rare 

 occurrence. This hypothesis diiTers from that of Mohr in that the 

 plants are microscopic. 



Petzholdt°° at once made a fierce critique of Reinsch himself, 

 his methods and his results. Of the seven divisions of Protophytce 

 two are decomposition products, three are certainly inorganic, one 

 consists of fragments of land plants and one is based on minute 

 fragments of coal. The decomposition products, mistaken for 

 organic bodies, are termed bitumen by Petzholdt, who thinks them 

 the same with those discovered fifty years before by Hutton in his 

 study of the Newcastle coals. 



Fischer and Rust,-'^ following Reinsch's method, found not only 

 yellow and reddish resin-like bodies in black coal, such as make up 

 the great part of the Scotch boghead, but also small grains, showing 

 wood structure, in anthracite. In the black coal, they observed 

 spindle-shaped or serpent-shaped bodies, whose relations they could 

 not determine. The English cannel from Lancashire is very rich 

 in little resinous cylinders and, as far as richness in resinous matter 

 is concerned, is intermediate between the Bogheads and the ordinary 

 coals. These studies have an important bearing on investigations 

 which have attracted much attention in more recent years. 



Green"- says that it is not easy to see how light material, such 

 as dead wood, could be spread out evenly over tracts of hundreds 

 of square miles, so evenly that the deposit shows comparatively little 

 variation in thickness ; and it is equally difficult to understand how, 

 in case the coal be composed of drifted materials, it could be so 

 pure as we often find it. The water bringing the vegetable matter 



""A. Petzholdt, " Beitrag zur Kenntniss der Steinkohlenbildung," Leip- 

 zig, 1882, pp. 23 et seq. 



"' H. Fischer and D. Rust, " Ueber d. mikroskopische Verhalten verschie- 

 dener Kohlenwasserstoffe, Harze und Kohlen," Croth Zcitschrift f. Kryst., 

 Vol. VIL, pp. 209-243. This has not been seen by the writer. Cited by 

 Petzholdt and v. Giimbel. 



'-A. H. Green, "Geology," Part L, Physical Geology. London, 1882, pp. 

 257-262. 



53 



