140 PRACTICAL BOTANY. 



thick cellulose walls (blue with Schulze's solution), and 

 protoplasmic contents with chlorophyll. Many cells 

 have recently divided (this is necessary to keep pace 

 with the growth in thickness of the vascular cylinder). 

 Large intercellular spaces (Resin-passages) occur here 

 and there, and are lined with small-celled epithelium. 



It must be remembered that in the present case the resin 

 itself has been dissolved out by alcohol. Sections should, there- 

 fore, be made from fresh material in order to see the secretion in 

 situ. It appears amorphous and transparent ; it is soluble in 

 alcohol, leaving a slight residue. N.B. All resins are not so 

 easily soluble. 



The secretion stains deeply with tincture of alkanet. 



Near the periphery of the cortex will be found a- 

 layer of Cork and a Cork-cambium (cf. stem of Elm 

 p. 70), derived from cells of the cortex by their division 

 by tangential walls. The cells of the cork have no 

 cell-contents ; their walls are coloured yellowish brown 

 with Schulze's solution. 



Treat a section with strong sulphuric acid. The walls of the 

 cork retain their sharp contour. 



At the bases of the indentations of the margin of 

 the section, and immediately below the epidermis note 

 groups of Sclerenchyma, having thick lignified walls 

 (yellow with Schulze's solution). 



3. The Vascular system : here a complete ring 

 (cf. the bud) : distinguish as before (a) the external 

 Phloem, (6) the internal Xylem, (c) the misty layer 

 of Cambium. 



N.B. The vascular bundles were seen to be separated 

 in the bud by intervening parenchyma. Here the ring 



