EXOGONIUM PURGA. 
393 
The above were those which succeeded best 
under the circumstances in the case alluded 
to. Some slight allowance should probably 
be made for the relative strength and vigour 
of the bulbs, which would in some degree in- 
fluence their success ; but as there were in 
most cases as many as four bulbs of each 
kind planted, and in many cases more than 
this number, the result may be regarded as a 
pretty good index of what may be expected 
from the same varieties in other instances. It 
may be well to remark, that when Hyacinths 
are planted out-doors, it is better to plant a 
large number of one kind than to intermix 
them. The remarks, early, medium season, 
and late, are intended simply to indicate the 
relative conditions of their blooming period ; 
those marked early being first in bloom, and 
being also in perfection at the same time; and 
the same with the later varieties. 
EXOGONIUM PUEGA. 
(Bentliam.) 
THE PURGA, OR TRUE JALAP. 
The drug sold under the name of jalap is 
the tuberous roots of a convolvulaceous plant, 
the true jalap being that of Exogonium 
(or Ipomcea) JPurga, but the roots of other 
species are at times substituted for those of 
the true kind. Jalap was at one time sup- 
posed to be the produce of Ipomcea macro- 
rhiza (the Convolvulus Jalapa of Linnasus), 
which produces large roots weighing from 
forty to fifty pounds each ; but the root of this 
species has been ascertained to consist chiefly 
of saccharine and farinaceous matter, and to 
possess no purgative properties. A kind of 
jalap called Purga Macho, Jalapa Macho, or 
Male Jalap, by the Mexicans, is produced by 
a plant called Ipomcea orizabensis ; this is ex- 
tremely similar in quality to the true jalap. 
Although jalap has been used in European 
medicine for nearly two centuries and a half, 
yet it is only within a few years that the plant 
which furnishes it has been accurately ascer- 
tained. 
Exogonium Purga is a very beautiful 
climbing plant. It has roundish tubers, which 
sometimes become as large as a moderate sized 
turnip, and produce numerous stems, which 
are glabrous, turning from right to left, and 
extending ten or twelve feet. The leaves are 
alternate, acutely heart-shaped, or somewhat 
arrow-shaped, with a rounded, deeply lobed 
base, smooth, and of very moderate size. The 
flower stalks grow from the axils, and usually 
bear each two or three flowers (very rarely 
one) ; they are between funnel and salver 
shaped, shiny, and of a light purplish red, or 
rosy lilac colour ; the tube is slender and club 
shaped, about two inches long, slightly taper- 
ing, and terminating in a nearly flat expanded 
limb of two and a half inches across. The 
flowers are very abundantly produced at the 
latter end of the summer. The plant grows 
on the mountains of Mexico. Schiede found 
it at a great elevation, on the eastern slope of 
the Mexican Andes, near Chiconquinaco, and 
near San Salvador, or the eastern slope of 
Cofre de Perote. Hartweg also met with it 
on the mountains of Orizaba. The true jalap 
plant seems to have been first sent from 
Mexico by Dr. Houston ; at least seeds sent 
by him produced plants with smooth leaves, 
the Convolvulus Jalapa having downy leaves. 
Dr. Coxe, of Philadelphia, sent living roots 
