i88 . REINHARDT THIESSEN 



directions and hence are lenticular bodies and definite components, 

 and are in reality not layers in the strict sense but lenticular masses. 



These components vary, of course, greatly in size and form. 

 Their lateral dimensions may range, as already intimated, from a 

 few millimeters to that of many feet; and in shape may range from 

 that of being approximately equilateral, oval, or circular to that 

 of being many times longer than wide. They are all relatively 

 thin, ranging from a thickness barely visible to that of several 

 inches. But strips of a thickness of more than one or two inches 

 are rare and even such of thicknesses approaching one inch are by 

 no means frequent. 



^''Bright coal" is anthraxylon. — It is not difficult to show that the 

 so-called "bright coal" are components that are derived from the 

 woody parts of plants, parts that at one time were largely composed 

 of wood. Thin sections were cut, both cross-wise and parallel to 

 the bedding planes, from a considerable number of bands of bright 

 coal from a number of different beds and were examined with the 

 view of determining their origin. Every one examined proved to 

 be derived from some woody plant tissue, either of stem, branch, or 

 roots. In every one the cell structure was well-enough preserved 

 so as to leave no doubt as to its origin. "Bright coal" has yet to 

 be found in which no trace of cell structure is observable. 



A good example, representing average conditions of the cell 

 structure is shown in Figures 3 and 5. These photographs repre- 

 sent cross-sections of the woody fibers, or, as it is often called, 

 sections across the grain. It will be noticed that the walls have 

 collapsed and are pressed very intimately together, but that the 

 actual mass of the cell walls has retained most of its original 

 matter. There is, however, a considerable variation in this respect 

 in different components and even in the same components, as is 

 shown in Figure 3. In the upper part of this photograph the cell 

 walls have retained most of their original mass, while those shown 

 in the lower part have become thin and in spots poorly definable, a 

 large part of the cell walls having vanished. In some pieces the 

 remaining tissue resembles that of well-preserved sound wood, 

 except that the walls have collapsed; in other cases again the 

 remaining structure is barely recognizable; the whole tissue has 



