256 



BARKS 



The inner surface is pale reddish pink in colour and finely striated 

 longitudinally ; small portions of white wood, which is seen hi transverse 

 section to be dense and traversed by numerous thin medullary rays, 

 are frequently found adhering to it. 



The outer portion of the bark (cork and cortex) breaks with a 

 short fracture, but the inner portion (bast) is coarsely fibrous and 

 disposed to separate into laminae, due to its containing numerous 

 tangentially elongated groups of bast fibres. The smoothed transverse 

 section exhibits under the lens a dark narrow 

 cortex and a pale tangential line (sclerenchy- 

 matous cells) separating this from the bast. In 

 many of the pieces the cork and much of the 

 cortex have been removed, and the ring of scleren- 

 chymatous cells may then form the outer layer. 



The bark has no odour, and an astringent, 

 slightly bitter taste. 

 The student should observe 



(a) The reddish pink colour, 



(b) The pale grey but not glossy cork, 



(c) The line of sclerenchymatous cells between 



the cortex and bast ; 



and should compare this bark with 



(i) Oak bark, which has a glossy, silvery cork 



and usually a brownish colour, 

 (ii) Willow bark, which has a dull greenish 

 brown cork, is usually longitudinally 

 striated on the outer surface, and does 

 not exhibit a line of sclerenchymatous 

 cells. 



FIG. 130. Witch- 

 hazel bark, show- 

 ing scaly cork. 

 Natural size. 



Constituents. The bark contains about 6 per 

 cent, of tannin, part of which, hamamelitannin, 

 is said to be crystalline and part amorphous ; 

 gallic acid is also present (Gruttner, 1898). 



Uses. It is astringent and haemostatic, and is useful in haemor- 

 rhages from the nose, lungs, rectum, or uterus. 



POMEGRANATE BARK 

 (Cortex Granati) 



Source, &C. The pomegranate tree, Punlca Grandtum, Linne 

 (N.O. Lythrariece), is a shrub or small tree indigenous to North- 

 western India, but cultivated generally in the warmer parts of the 

 temperate regions, especially in the countries bordering on the 



