210 APPENDIX. 



sections of one quarter. [You should attempt to cut a very 

 small piece only.] Shew on your sketch the medullary 

 rays as strands of from two to ten or more rows of cells 

 running from the centre outwards across the fibres and 

 dotted vessels. Your section may possibly shew also the 

 spiral vessels next the pith. 



vi. Carefully examine specimens of old stems of 

 various sorts and identify the medullary rays (silver 

 grain), and the annual rings as seen in bulk. 



No. VI. 



PHLOEM AND CORK. 



i. Cut accurately transverse sections of a small piece 

 of the bark of the Oak stem and of the wood attached to 

 it. Shew on your sketch drawn under low power, but 

 using the high power where necessary, 



a. soft phloem, consisting of sieve tubes and com- 

 panion cells ; 



b. hard phloem, isolated small patches of white, very 

 thick-walled elements ; 



c. numerous cluster-crystals of calcium oxalate, more 

 numerous in the soft phloem ; 



d. small groups of thick-walled, pitted, sclerenchy- 

 matous cells ; 



e. primary cortex ; 



/ cork on the outside; immediately beneath it the 

 cells are flattened and brick-shaped : these constitute the 



