liAmX BELLAL>U.N^./E. 457 



Microscopic Structure — There is a considerable stnictural differ- 

 ence between the main root and its branches, the former alone contain- 

 ing a distinct pith. This pith is included in a woody circle, traversed 

 by narrow medullary rays. In the outer part of the woody circle, 

 parenchymatous tissue is more prevalent than vascular bundles. The 

 transverse section of the branches of the root exhibits a central vascular 

 bundle instead of a medullary column. The outer vascular bundles 

 show no regular arrangement ; and medullary rays are not clearly 

 obvious in the transverse section. 



The woody parts, both of the main root and its branches, contain 

 very large dotted vessels accompanied by a prosenchymatous tissue. 

 The cells of the latter, however, are always thin-walled ; the absence of 

 proper so-called ligneous tissue explains the easy fracture of the root. 

 Sometimes the prosenchynie in which the vessels ,are imbedded assumes 

 a brownish hue and a waxy appearance, and such parts exhibit a very 

 irregular structure. 



In the cortical portion of belladonna root, many of the cells of the 

 middle layer, and likewise some of the central parts of the root, are 

 loaded with extremely small octahedric crj^stals of calcium oxalate. 

 But most of the parenchymatous cells are filled up with small starch 

 granviles. 



Chemical Composition — In 1833 Mein prepared from the root, 

 and Geiger and Hesse from the herb, the crj'stallizable alkaloid 

 Atropine. The researches of Lefort (1872) have proved that the roots 

 (tontain it in very variable proportions, the young being much richer 

 in alkaloid than the old.^ The maximum proportion obtained was OG 

 per cent.; this was from root of the thickness of the finger. Large old 

 roots, 7 or 8 years of age, afford from 025 to 0:31 per cent. They have 

 besides a smaller proportion of bark than young roots, and it is chiefly 

 in the bark that the alkaloid appears to reside. Manufacturers of 

 atropine employ exclusively the root. 



Ludwig and Pfeiffer (1861), by decomposing atropine with potassium 

 chromate and sulphuric acid, obtained benzoic acid and propylamine. 

 Other products are formed when atropine is treated with strong hydro- 

 chloric acid, baryta water or caustic soda, thus — Atropme, C'H'^NO' 

 -I- H^^O = Tropic Acid, CWO"" + Tropine, Cff'^NO. 



Tropic acid, C^H^C (OH) j qqq jj , being further boiled with the 



f OH' 

 same agents is converted into atropic acid, C®H'C < (^r^rtU' which, 



especially by using hydrochloric acid, is gradually transformed into 

 isotropic acid. Both these acids are isomeric to cinnamic acid, CH^O", 

 but otherwise remarkably dissimilar. 



Tropine is a strongly alkaline body, readily soluble both in water 

 and alcohol, and furnishing tabular ciystals by the evaporation of its 

 solution in ether. Neither tropine nor tropic acid, it is stated by 

 Kraut (1863), is present in the leaves and root of belladonna. 



Hiibschmann (1858) detected in belladonna root a second but un- 

 crystallizable alkaloid, called Belladonnine ; it has a resinous aspect, 

 is distinctly alkaline, and when heated emits, like atropine, a peculiar 

 odour. 



1 For Lefort's process for estimating atropine, see p. 458. 



