372 



THE MICROSCOPE AND ITS REVELATIONS. 



that of the medullary rays, and therefore cuts them across, we see that 

 each of the plates thus formed has a very limited depth from above 

 downwards, and is composed of no more than one thickness of horizontal 



Tm. 2o!) 



T?IG. 2RO. 



Portion of Vertical Section of the 

 same wood, taken in a radial direc- 

 tion, showing the glandular Woody 

 fibres, without Ducts, crossed by the 

 Medullary Rays, a, a. 



Portion of Vertical Section 

 of the same wood, taken in a 

 tangential direction, so as to 

 cut across the Medullary 

 Rays. 



cells. A section of the stem of Mahogany taken in the same direction as 

 the last (Fig. 261), gives a very good view of the cut ends of the medullary 

 rays, as they pass between the woody fibres; and they are seen to be here 



E10.-SGS, 



FIG. 261. Vertical Section of Mahogany. 



Fig. 262. Transverse section of a Fossil Wood; snowing the Medullary Rays, a, a, a, a, a, a, 

 running nearly parallel to each other, and the openings of large Ducts in the midst of the woody 



Fig. 263. Vertical (tangential) section of the same wood; showing the Woody fibres separated 

 by the Medullary Rays, and by the large Ducts, b 6, b 6. 



of somewhat greater thickness, being composed of two or three rows of 

 cells, arranged side by side. 



