CORTEX ULMI FULVvE. 557 



Chemistry — The chief soluble constituent of elm hark is mucilage 

 with a small proportion of tannic acid, the latter, according to Johanson 

 (1875), probably agreeing with that of oak bark and bark of willows. 

 The concentrated infusion of elm bark yields a brown precipitate with 

 perchloride of iron; the dilute assumes a green coloration with that test. 

 Starch is wanting, or only occurs in the middle cortical layer, which is 

 usually rejected. 



Elms in summer-time frequently exude a gum which, by contact with 

 the air, is converted into a brown insoluble mass, called Ulmia. This 

 name has been extended to various decomposition-products of organic 

 bodies, the nature and affinities of which are but little known.^ 



Uses — Elm bark is prescribed in decoction as a weak mucilaginous 

 astringent, but is almost obsolete. 



CORTEX ULMI FULViE. 

 Slippery Elm Bark. 



Botanical Origin — Ulmus fulva Michaux, the Red or Slippery Elm, 

 a small or middle-sized tree,- seldom more than 30 to 40 feet high, grow- 

 ing on the banks of streams in the central and northern United States 

 from Western New England to Wisconsin and Kentucky, and found 

 also in Canada. 



History — The Indians of North America attributed medicinal virtues 

 to the bark of the Slippery Elm, which they used as a healing application 

 to wounds, and in decoction as a wash for skin diseases. It is the " Salve 

 Bark" or " Cortex unguentarius " of Schopf* Bigelow, writing in 1824, 

 remarks that the mucilaginous qualities of the inner bark are well 

 known. 



Description — The Slippery Elm Bark used in medicine consists of 

 the liber only. It forms large flat pieces, often 2 to 3 feet long by 

 several inches broad, and usually ^V to ^ of an inch thick, of an ex- 

 tremely tough and fibrous texture. It has a light reddish-brown colour, 

 an odour resembling that of fenugreek (which is common to the leaves 

 also), and a simply mucilaginous taste. 



In collecting the bark the tree is destroyed, and no effort is made to 

 replace it, the wood being nearly valueless. Thus the supply is dimin- 

 ishing year by year, and the collectors who formerly obtained large 

 quantities of the bark in New York and other eastern states have now 

 to go' westward for supplies.* 



Microscopic Structure — The transverse section shows a series of 

 undulating layers of large yellowish bundles of soft liber fibres, alter- 

 nating with small brown parenchymatous bands. The whole tissue is 

 travei'sed by numerous narrow medullary rays, and interrupted by large 

 intercellular mucilage-ducts. In order to examine the latter, longitu- 

 dinal sections ought to be moistened with benzol, aqueous liquids causing 

 great altei-ation. In a longitudinal section, the mucilage-ducts are seen 



* Gmelin, ChemUtrij, xvii. (1866) 458. ' Mat. Med. Americ, Erlangie, 1787. 32. 



' Fig. in Bentley and Trimen's Med. * Proceedings of the American Phamin- 



Plants, part 34 (1878). ceutical Association/or 1873, xxi. 435. 



