274 BARKS 



warty cork, which can easily be scraped off, disclosing a darker inner 

 portion. The inner surface is walnut-brown, bears shallow, rather 

 broad longitudinal depressions, and is coarsely longitudinally striated 

 by strands of sclerenchymatous tissue, which, under the lens, can 

 be seen slightly projecting beyond the remaining parenchymatous 

 tissue. 



The bark is extremely hard, and breaks with a short granular 

 fracture. The transverse section, smoothed and moistened, exhibits 

 under the lens a very narrow, pale grey cork ; the remainder of the 

 bark is completely traversed by closely approximated, yellowish, wavy 

 medullary rays, showing that in the majority of cases the drug consists 

 (with the exception of the cork) of bast tissue. Between the medullary 

 rays numerous minute groups of sclerenchymatous cells can be dis- 

 tinguished, arranged in radial lines. 



The bark has no odour, but a bitter taste. 



The student should observe 



(a) The flat heavy pieces, 



(b) The thin grey cork, 



(c) The structure of the transverse section ; 



and should compare this bark with 



(i) Sassy bark, which is seldom flat, is often nearly black on 

 the inner surface, and exhibits in transverse section 

 large conspicuous groups of sclerenchymatous cells ; 



(ii) Goto bark, which has a reddish brown colour, is usually 

 much thicker, and has a characteristic odour and 

 taste ; 



(iii) Elm bark, which is much paler in colour and fibrous. 



Constituents. The chief constituents of bebeeru bark are the alka- 

 loids beberine and siperine and probably others that have not yet 

 been isolated. 



Beberine, C 19 H 21 N0 3 , crystallises in colourless prisms melting at 214. It 

 has a bitter taste, and forms colourless crystalline salts. It is identical with 

 pelosine (see ' Pareira brava '), but distinct from buxine, a similar alkaloid 

 occurring in box. 



Siperine has been obtained in the form of dark scales of very doubtful purity. 



The commercial sulphate of beberine in dark brown scales, which was official 

 in the British Pharmacopoeia of 1885, is not a pure sulphate of the alkaloid. 

 It contains about 30 per cent, of beberine associated with siperine and probably 

 other alkaloids, as well as with much colouring matter. 



. Bebeeru bark is a bitter stomachic and tonic ; the alkaloid 

 is, to a small extent, antipyretic, but these effects being insignificant, 

 its use in fever and ague has now been abandoned. 



