CORTEX CASSIA LIONEL. 531 



have a pale cinnamon hue, but most are of a deep rich brown. They 

 present all variations in thickness, from that of cardboard to more than 

 a quarter of an inch thick. The flavour is more or less that of cinna- 

 mon, often with some unpleasant addition suggestive of insects of the 

 genus Ciinex. Many, besides being aromatic, are highly mucilaginous, 

 the mucilage being freely imparted to cold water. Finally, we have 

 met with some thick cassia bark of good appearance that was 

 distinguished by astringency and the almost entire absence of 

 aroma. 



Microscopic Structure — A transvei^se section of such pieces of 

 Chinese Cassia lignea as still bear the suberous envelope, exhibits the 

 following characters. The external surface is made up of several rows 

 of the usual cork-cells, loaded with brown colouring matter. In pieces 

 from which the cork-cells have been entirely scraped, the surface is 

 formed of the mesophloeum, yet by far the largest part of the bark 

 belongs to the liberorendophloeum. Isolated liber-fibres and thick- walled 

 cells (stone-cells) are scattered even through the outer layei-s of a trans- 

 verse section. In the middle zone they are numerous, but do not form 

 a coherent sclerenchymatous ring as in cinnamon (p. 526). The inner- 

 most part of the liber shares the structural character of cinnamon 

 with differences due to age, as for instance the greater development of 

 the medullary rays. Oil-cells and gum-ducts are likewise distributed 

 in the parenchyme of the former. 



The " China Cinnamon " of 1870 (p. 530) comes still nearer to 

 Ceylon cinnamon, except that it is coated. A transverse section of a 

 quill, not thicker than one millimetre, exhibits the three layers de- 

 scribed as characterizing that bark. The sclerenchymatous ring is 

 covered by a parenchyme rich in oil-ducts, so that it is obvious that the 

 flavour of this drug could not be improved by scraping. The corky 

 layer is composed of the usual tabular cells. The liber of this drug in 

 fact agrees with that of Ceylon cinnamon. 



In Cassia Barks of considerable thickness, the same arrangement of 

 tissues is met with, but their strong development causes a certain dis- 

 similarity. Thus the thick-walled cells are more and more separated 

 one from another, so as to form only small groups. The same applies 

 also to the liber-fibres, which in thick barks are surrounded by a paren- 

 chyme, loaded with considerable cr3"stals of oxalate of calcium. The 

 gum-ducts are not larger, but are more numerous in these barks, which 

 swell considerably in cold water. 



Chemical Composition — Cassia bark owes its aromatic properties 

 to an essential oil, which, in a chemical point of view, agrees with 

 that of Ceylon cinnamon. The flavour of cassia oil is somewhat less 

 agreeable, and as it exists iu the less valuable sorts of cassia, decidedly 

 different in aroma from that of cinnamon. We find the sp. gr. of 

 a Chinese cassia oil to be 1066, and its rotatory power in a column 

 50 mm. long, only 0°-l to the right, differing consequently in this respect 

 from that of cinnamon oil (p. 526). 



Oil of cassia sometimes deposits a stearoptene, which when purified 

 is a colourless, inodorous substance, crystallizing in shining brittle 

 prisms.^ We have never met with it. 



^ Rochleder and Schwarz (1850) in Gmelin's Chemistry, xvii. 395. 



