670 STEVENSON— FORMATION OF COAL BEDS. [November 3, 



by water, heat or the activity of the plant, this is ready to resist the 

 rains and winds, for its adhesion is complete on the steepest slopes. 



After spreading for sometime, the Eriospora lifts its rhizomas 

 into the air and sets off branches, each terminated by a bouquet of 

 grass-like leaves, and each year, before the rains, abundant rosettes 

 of leaves and flowering twigs are developed at the end of these rhi- 

 zomas. At the beginning of the dry season, these leaves wither and 

 soon afterward they are consumed by fires lightedby men or perhaps 

 by lightning; only the bases of the leaves remain; blackened, half- 

 carbonized, this coat thickens around the rhizoma. The growth of 

 the Eriospora tufts is apparently very slow, but, as they may live 

 for several centuries, they attain notable dimensions. On the border 

 of the virgin forest, some were seen more than a meter high and 

 half a meter thick at the base. The stem divides midway into ver- 

 tical branches, themselves dividing, the last division having a diam- 

 eter of 2 to 3 centimeters. 



The tufts are not always in contact, there being at times an inter- 

 val of even 50 meters, but in these intervals on gentle slopes, one 

 finds a fibrous network, very humic, constituting a veritable bed of 

 peat, 5 to 30 centimeters thick. This peat is formed not only of 

 roots and rhizomas, but also of young colonies of Eriospora^ killed 

 soon after origin by fire or by lack of light. True mosses appear at 

 high altitudes. On the humid flank of Mount Momry, Chevalier 

 found a Sphaguum at 850 to 900 meters above sea level. The Erio- 

 spora peat covers tens of thousands of hectares in French west 

 Africa. The condition described by Chevalier is not wholly unfa- 

 miliar in the temperates, where mosses and other plants cover irreg- 

 ular rocky surfaces and form a coating of peat at times several inches 

 thick. This is seen frequently in the southern Appalachians. It is 

 the Rohhumus or Trockentorf of the Germans. 



It was reserved for Potonie'^ to present the final evidence. Find- 

 ing no available literature giving details respecting moorformation 

 in the tropics, he applied to Koordes, botanist of the Dutch expe- 

 dition across Sumatra in 1891. Koordes informed him that in old 



"11. Potonie, "Die Entstehung der Steinkolile iind der Kaustobiolitlie 

 iiljciiiaupt," 5th Aufl., Berlin, 1910, pp. 152-160. 



168 



