BELLADONNA 



45 



others. Each stoma is surrounded by three or four cells, one of which is smaller 

 than the others ; the epidermal cells have sinuous walls and striated cuticle. 



The student should observe 



(a) The upper leaves in unequal pairs, 



(b) The glabrous surface, 



(c) The presence of whitish raised points (on the dried leaves) ; 



and should compare the dried leaves with 



(i) Stramonium leaves, which 

 curl and twist as they 

 dry, have a character- 

 istic odour and sinuate- 

 dentate outline, 



(ii) Foxglove leaves, which are 

 hairy, 



(iii) Henbane leaves, which 

 are hairy. 



Constituents. The chief consti- 

 tuents of the drug are the alkaloids 

 hyoscyamine and atropine. Good 

 samples contain about 0'4 per cent, 

 of total alkaloid, but as much as 1 

 per cent, has (exceptionally) been 

 found. The alkaloids are contained 

 in all parts of the plant ; in the 

 calices and young ovaries 0'79 per 

 cent, has been found, in the ripe 

 seeds 0'83 per cent., in the root 

 0'5 per cent., and in fresh fruit 

 0'12 per cent. 



Belladonna leaves also contain a 

 fluorescent substance, /3-methyl- 

 sesculetin (scopoletin, chrysatropic 

 acid), and yield about 14 per cent. 



FIG. 31. Belladonna 

 surface, showing 

 Natural size. 



of ash. 



Under 

 venation. 



Hyoscyamine, C 17 H 23 NO 3 , forms colourless crystals melting at 108'5; it 

 is Isevorotatory [a] D = 29-97), and is converted by heating to 110 into its 

 isomer atropine. Atropine differs from hyoscyamine in having a higher melting- 

 point, viz. 115, and in being optically inactive : it is the racemic modification 

 and can be resolved into laevo- and dextro -hyoscyamine, the latter being much 

 less active than laevo -hyoscyamine. Both hyoscyamine and atropine yield 

 tropine and tropic acid when hydrolysed by heating with baryta water. Hyos- 

 cyamine crystallises less readily than atropine, is more soluble in water and dilute 

 alcohol, and yields with gold chloride an aurichloride (C 17 H 23 N6 3 ,HCl,AuCl 3 ), 

 crystallising in brilliant yellow scales, melting at 160, whereas the corre- 

 sponding atropine gold salt crystallises in dull warty prisms melting at 136. 

 Other alkaloids (belladonnine, apoatropine) may possibly also be present, but 



