194 BAEKS. 



(95) Cinnamon Bark. 



The bark of Cinnamomum zeylanicum, Breyne (N.O. Lau- 

 rinese). 



The bark, which is deprived of the cork and of the majority 

 of the cortex, presents the following structure : 



(1) Cortex, represented by two or three rows of tangentially 

 elongated polygonal cells. 



(2) Bast Ring, separated from the remains of the cortex by a 

 continuous ring of sclerenchymatous cells, with thickened 

 pitted walls, the thickening being often more strongly 

 developed on one side than on the others. On the outer margin 

 of this ring bundles of pericyclic fibres may be detected at 



ntervals, as in the case of cassia bark, but the sclerenchymatous 

 ring of cinnamon differs from that of cassia in being continuous 

 instead of interrupted. The bast ring is traversed by medullary 

 rays', which are very narrow near the cambium, but enlarge 

 towards the periphery. It contains secretion cells similar to 

 those of cassia bark, and bast fibres that have very thick walls 

 and are mostly isolated. The sieve-tubes are arranged in tan- 

 gential groups, which in the outer portions of the bast ring are 

 collapsed and exhibit traces only of cavities ; they are narrow 

 and have transverse sieve-plates. Many of the cells of the 

 cortical parenchyma and medullary rays contain small starch 

 grains or numerous minute crystals of calcium oxalate. 

 The diagnostic characters of cinnamon bark are : 



(a) The absence of cork. 



(b) The sclerenchymatous cells, sometimes thickened on 



one side more than on the others. 



(c) The secretion cells containing oil or mucilage. 



(d) The minute crystals of calcium oxalate. 



(e) The small sieve-tubes with transverse plates . 



Typical cinnamon bark is distinguished from cassia bark by 

 the absence of cork, by the bast-fibres, which are smaller and 

 narrower, and by the starch grains, which are also smaller. 



