231 



V. BARK. 



(rt) Economic (vide Chemistry). 



(h) Anatomy. 



A fairlv comprehensive series of sections of this bark is given. The cross- 

 sections show a structure similar to that of its congeners, the layers of periderm 

 being restricted to the outer cortex, and in Figure 152 are shown as dark parallel 

 bands running from top to bottom of the picture, the dark colour probably being 

 due to the manganese compound and tannin contents, whilst Figure 154 shows 

 one periderm band passing diagonally through the picture, where the black 

 manganese contents of the parenchymatous cells are also well defined. Medullary 

 strands are illustrated in Figures 151-153, and in the latter the lysigenous nature 

 of oleo-resin cavities is clearh' shown. 



Two longitudinal sections are given under Figures 155 and 156. The 

 former is interesting as sho^^ing the parenchymatous nature of the medullary 

 cells, and more especially is this feature seen in the concentric cells between 

 the sieve tubes. The dark cell contents to the left mark the presence of the 

 manganese compound. 



The pale coloured structure composed of thin-walled cells running through 

 the centre of the picture, Figure 155, from top to bottom, marks the band of 

 periderm, and in this case forms the median material between the inner, on the 

 left, and the outer bast. Figure 156 illustrates a longitudinal section of bark, 

 and shows the sieve plates of the tubes, as well as the latter's position in the 

 bark structure. A parenchymatous cell runs through the centre of the picture 

 from top to bottom ; this is bounded on both sides by sieve tubes, that on the 

 right sho\\ing the plates particularly well. Each of these tubes is in turn in 

 juxtaposition to a bast fibre. 



(c) Chemistry. 



The log from which this bark was taken was obtained near Svdney. Its 

 diameter was 8 inches. The bark was thin and somewhat fibrous, and its thickness 

 was from 6 to 10 mm. It was externally of a dark-brown colour, and was com- 

 paratively deepl\- furrowed. From the results obtained with this specimen it 

 has little value for tanning purposes. 



The follo\nng results were obta 



Moisture ... 

 Total extract 

 Non-tannin 

 Tannin 



ned with the air-dried bark: — 

 14-5 per cent. 



■ 7-^ „ 



■ 3-8 „ 

 • 4-0 



