208 APPENDIX. 



f. companion cells ; 



g. phloem parenchyma ; 



h. pericycle fibres ; long narrow elements with thick- 

 ened walls ; 



i. endodermis ; a single layer of cells containing 

 starch grains; 



k. cortex similar to the pith. 



I. epidermis. 



[If you fail to get successful sections by this method 

 it is advisable to cut out a small piece of your tissue 

 containing a vascular bundle, and imbed it in pith. To 

 do so, slit a piece of Elder pith longitudinally with a 

 sharp knife and place your tissue in the slit so that the 

 radius of the stem passing through the bundle is level 

 with the pith edge. Pare off the pith, leaving only a 

 small area round the imbedded tissue, and cut sections 

 of the tissue and of the imbedding pith together : the 

 pith is easily separated on washing the sections from 

 the razor into a watch-glass of water. Do not use your 

 section razor for slitting or paring pith, which should be 

 done with the older razor used for rough work.] 



No. V. 



THE ARBOREAL STEM. 



i. Cut transverse sections of an Oak twig of the 

 current year. Mount in glycerine and examine with a 

 low power. Show on your sketch 



a. epidermis ; 



6. cortex ; 



