RHAMNEZR. 353 
inner layers consist of pale liber fibres running through a mass 
_ of cells containing yellowish-brown colouring matter of a waxy 
consistence. ‘The inner surface is dark chocolate-brown, be- 
coming almost black when kept for some weeks. The fracture 
_ 4s short externally, and tough and fibrous internally. A section 
_ touched with a drop of potash solution becomes intensely red, 
_ With ferric chloride dirty green, and with iodine solution black. 
g ‘The taste is astringent and bitter, but not unpleasant, a 
_ Sweetish after-taste being left on the palate. The odour of the 
bark recalls that of tan. 
Microscopic structwre.—A microscopic examination shows that 
throughout the parenchyma, especially of the mesophlceum, thers 
are a number of aggregate crystals, more plentiful in older 
- Specimens. The mesophlceum contains many thick-walled cells. 
_ The medullary rays and inner cellular layers are filled with 
starch granules. A yellow colouring matter, residing princi- 
pally in the liber and cambium, becomes brilliantly red in con- 
tact with potash solution. In the cells surrounding the liber 
_ vessels, are numerous large rhomboidal crystals. 
Chemical composition.—The bark has been examined by 
Ee D. Hooper (Pharm. Journ. Feb, 1888), with the following 
: 
results :— 
Crystalline principle’ .. 0°47 
Light brown resin soluble in ether ... 0°85 
Red resin soluble in ether ............... 1°15 
Red acid resin soluble in‘alcohol ...... 4°56 
Indifferent a—resin sol. in alcohol .... 3°80 
Indifferent s—resin sol. in alcohol .... 1°64 
Tannin.:.... 2-68 
Bitter principle ee ae 
Sugar reducing sec: oe 
Sugar non-reducing 10:22 
Malic acid (?) es ae! 
Cathartic acid : 4:42 (oe 
Extractive soluble in water erat se ie 4 
Albuminous mat = eee 
Modification of arabin sol. in n alkali ae 
5 
