202 REINHARDT THIESSEN 



frequently with a short cross slit at or near one of the ends of 

 the longitudinal slit, but a tetrasporic mark is never seen. The 

 absence of the tetrasporic mark and the presence of a slit then are 

 characteristic characters. In color, transparency, and consistency 

 they are similar to the true spore-exines. Their surface is always 

 smooth and has no spines, processes, or hairlike coverings. They 

 vary greatly in size, indicating that a considerable number of 

 species or genera of plants are involved. Compare Figures 25 and 

 30, photographed at the same magnification. 



The resinous matter. — There are universally scattered through 

 or contained in the attritus of all coals, certain particles, which, 

 when seen under the microscope, are generally of a more or less 

 rounded or ovoid form, rarely angular or irregular; of a rather 

 homogeneous or vitrious consistency; of a brownish red to red 

 color, a color very similar to that of the anthraxylon components 

 and the humic matter, called resinous particles. Such form a 

 very appreciable part of many coals. These constituents are 

 classed under resinous matter, because they resemble very closely 

 certain constituents in peat and lignite where they are more cer- 

 tainly known to belong to the natural resinous substances of plants. 

 Many of the resinous-appearing bodies in the attritus, moreover, 

 very closely resemble certain bodies still included in the original 

 tissues of both the smaller and the larger anthraxylon components. 

 Further, there are clear cases of transition from where they are 

 still included in the original tissues to that where they are free in 

 the attritus. 



There is, therefore, enough basis for assuming that the con- 

 stituents in question are derived from the natural resins of the 

 Paleozoic plants. The proof is, nevertheless, not as positive as 

 one would like to have it. But since the constituents in question 

 stand in quite sharp contrast to the other constituents and are 

 tolerably well definable into a distinct class of components, the 

 term applied to them is believed to be justifiable. Besides, it 

 affords a convenient means to distinguish them from the other 

 constituents. 



Good illustrations of resinous matter in the attritus are given 

 in Figures 23 and 26, also in Figure 19. Figure 26 shows 



