(..399. ) 
XXXIII. On the Plant which the Gum Ammoniacum. 
By Mr. David Don, Libr. L.S. 
Read December 7, 1830. 
To discriminate and characterize those plants which more 
immediately administer to the wants and comforts of man, is 
one of the chief objects of practical botany; but it is a task 
replete with difficulties,—the countries whence many of the 
substances are derived, particularly those belonging to the Ma- 
teria Medica, being generally remote and often inaccessible to 
travellers. 
Although the gum Ammoniacum has held a place in the Ma- 
teria Medica from a very early period, yet the plant from which 
it is obtained has hitherto remained almost totally unknown ; 
and the same may be said of the analogous gum Galbanum, 
and many other articles derived from the vegetable kingdom 
enumerated in the Pharmacopeeia. It is true, Dioscorides and 
Pliny mention the plant which yields the gum Ammoniacum, 
the former under the appellation of Agasyllis, and the latter 
under that of Metopium, and give Libya as its native country: 
but if the gum was anciently imported thence, it must have 
been the produce of a different plant from the one I shall 
shortly describe; and probably identical with the species of 
Ferula represented by Jackson in his Account of Morocco, 
as the gum now comes to Europe by way of the Levant and 
India. Dioscorides, whose opinion is adopted by all subse- 
VOL, XVI. 4H quent 
