196 REINHARDT THIESSEN 



sides toward each other. Figure 17 is taken from a section con- 

 taining a large proportion of cuticular matter very similar to 

 that shown in Figure 16. Here the cuticles are represented by 

 comparatively heavy light-colored bands, sometimes in pairs 

 embedded in a general debris derived largely from leaves and other 

 vegetable matter. Cuticles are sometimes accompanied by well- 

 preserved leaf tissues. Cuticular matter is also present in a macer- 

 ated or more or less fragmented condition. When in this condition 

 it forms a constituent of the attritus, and is often difficultly dis- 

 tinguishable from fragmentary spore-exine matter which it closely 

 resembles in color and general appearance. 



Like the spore-exines the cuticles may very easily be separated 

 from the coal by means of Schulze's reagent. When thus separated 

 from the coal they appear as tissues or films constructed of cells 

 (Fig. 18). They are, however, non-cellular, hyaline membranes and 

 the apparent cell structure is due to ridges on the under surface 

 that conformed to the once underlying epidermal tissue. In cross- 

 section these ridges give the saw-edged appearance. A considerable 

 number of patterns of the apparent cell structure, or in other 

 words, different types of cuticles, are found, thus indicating that 

 a number of different species or genera of plants are involved. 



BARK 



It cannot be said with certainty that bark has contributed any 

 appreciable amount to coal; nothing has been met with that could 

 be referred to with certainty as derived from bark. There is, 

 however, a constituent reoccurring in all coals, most frequently 

 in the coal from the Pittsburgh seam, that might be interpreted 

 as being derived from bark. It is shown in Figure 6. This 

 component is always of a dark-brown color, lumpy, porous, and of 

 irregular structure. By far the largest proportion of it has retained 

 some of its original plant or cell structure. On the whole, the 

 remaining cell structure is very poorly and very irregularly pre- 

 served and appears to be derived from large-celled tissues. It 

 almost always includes a large number of resinous-appearing 

 globules, and frequently also more highly carbonized matter. 

 It also frequently includes parts of the tissues, or strands of tissues, 

 in which the plant structure is still well preserved. In some of 



