OF LOWER GREENS AND PLANTS. 



and linking two medullary rays maybe parenchyma (see Stopes, 

 1912, text-fig. 1). 



Medullary rays are very numerous and conspicuous. The 

 multiseriate rays are principally about 4 cells wide and a dozen 

 or more cells high. None of these rays run for any great radial 

 extent in the wood, but become uniseriate or die out altogether 

 (text-fig. 89, md.}. Those which reach the phloem expand 



Text-fig. 89. Aptiana radiata, Stopes. Transverse section of the stem 

 showing the texture of the wood, with its small vessels, and fibre- 

 tracheids in regular rows. The broad medullary rays, m., are con- 

 spicuous, the ray md. is seen to be dying out to a uniseriate ray, 

 [Note that this and fig. 80 are magnified exactly the same amount, 

 showing the great contrast between the two woods.] 



