MEDICAL BOTANY. 



Europe. Other writers have attributed it to Selinum gummiferum (Spren- 

 gel, Bot. Med. 477). The opinion of Jackson (Morocco), has already been 

 noticed. 



The first definite account of the origin of this gum was by Captain Hart, 

 in a letter to Dr. Wallich {Trans. Med. Soc. Calcutta, i. 369); he saw the 

 plant furnishing it in several places in Persia, and gives a general descrip- 

 tion of it, accompanied with a poor drawing. It was soon afterwards found 

 by M. Fontannier, who sent specimens to Merat, who considered them as 

 those of a Ferula, and proposed to retain it under the specific name given 

 by Lemery. Mr. Don, however, is of opinion that it forms the type of a 

 distinct genus, on which he has bestowed the appellation of Dorema, and 

 his views have been generally adopted. In addition to this, it may be men- 

 tioned, that Dr. Royle (Mat. Med., 413, note) states, that from fragments 

 of a plant obtained by Aucher-Eloy in the same localities, Jaubert and Spach 

 have described it under the name of Disernestum gummiferum ; this, Dr. 

 Royle thinks, is only the Dorema described from imperfect specimens. 

 From the above, it would appear that the gum-resin in question is certainly 

 the product of two dissimilar plants, one a native of Africa, the other of Per- 

 sia, and possibly that it may be afforded by other distinct Asiatic species. 



According to M. Fontannier, the gum-resin exudes spontaneously; but 

 Captain Hart says, that when the plant is mature, it is pierced in all direc- 

 tions by beetles, and from the punctures thus made, the juice flows out abun- 

 dantly, and when hardened is picked off. The finest pieces are kept sepa- 

 rate, and form the ammoniacum in tears, whilst the inferior kinds are 

 pressed together and constitute the lump ammoniacum. Major Willock 

 states, that the juice exudes principally from the stems, and either concretes 

 on them or falls to the ground; that it is collected in the autumn, and is 

 conveyed to ports on the Red Sea, whence it is taken to India, and thence 

 sent to Europe and this country. 



Gum ammoniac is moderately hard and brittle, but softens with a mode- 

 rate heat, is inflammable, partially soluble in water, wholly so in alcohol. 

 The taste is unpleasant, bitter, and somewhat acrid. The smell is peculiar, 

 but somewhat like that of galbanum, stronger in the lump than in the tears. 

 According to Braconnot (Ann. de Chim., Ixviii. 69) it is composed of Resin 

 70-; Gum 18*4; Gluteniform substance 4-4, &c. It also contains a small 

 portion of volatile oil. 



Its effects on the system are similar to, but less powerful than those of 

 assafcetida, and from containing much less volatile oil, not nearly as stimu- 

 lating. It appears to have special influence on the bronchial mucous mem- 

 brane, promoting expectoration. 



Medical Uses. — Its principal internal use is in chronic affections of the 

 respiratory organs, in which cases it has been of essential benefit, but is 

 wholly unsuited where there is inflammation or much irritation of the bron- 

 chial mucous membrane. It is seldom given alone, being usually combined 

 with other expectorants. Dr. Chapman (Therap., i. 507) speaks highly of 

 a mixture of it with nitric acid, where a large accumulation of purulent and 

 viscid matter exists, with feeble and difficult respiration. 



It has also been employed as a diuretic, emmenagogue, and antispasmodic, 

 and at one time was much esteemed as a deobstruent ; but is now seldom 

 prescribed to fulfil these intentions. As an external application, it is em- 

 ployed as a discutient in indolent tumours and chronic scrofulous swellings, 

 either alone or combined with mercury, and has been found very beneficial, 

 especially in cases of swellings about the joints. The dose of gum ammo- 

 niac is from 5 — 30 grains, either in pill or emulsion ; the latter form, either 



