STRUCTURE OF FOSSIL PLANTS 53 



CHAPTER VI 



MINUTE STRUCTURE OF FOSSIL PLANTS LIKENESSES 

 TO LIVING ONES 



The individual plants of the Coal Measure period 

 differed entirely from those now living; they were more 

 than merely distinct species, for in the main even the 

 families were largely different from the present ones. 

 Nevertheless, when we come to examine the minute 

 anatomy of the fossils, and the cells of which they are 

 composed, we find that between the living and the 

 fossil cell types the closest similarity exists. 



From the earliest times of which we have any know- 

 ledge the elements of the plant body have been the 

 same, though the types of structures which they built 

 have varied in plan. Individual cells of nearly every 

 type from the Coal Measure period can be identically 

 matched with those of to-day. In the way the walls 

 thickened, in the shapes of the wood, strengthening 

 or epidermal cells, in the form of the various tissues 

 adapted to specific purposes, there is a unity of organi- 

 zation which it is reasonable to suppose depends on 

 the fundamental qualities inherent in plant life. 



This will be illustrated best, perhaps, by tabulating 

 the chief modifications of cells which are found in plant 

 tissues. The illustrations of these types in the following 

 table are taken from living plants, because from them 

 figures of more diagrammatic clearness can be made, 

 and the salient characters of the cells more easily recog- 

 nized. Comparison of these typical cells with those illus- 

 trated from the fossil plants reveals their identity in 

 essential structure, and most of them will be found in 

 the photos of fossils in these pages, though they are 

 better recognized in the actual fossil^ themselves. 



