_Prunes_; F. _Pruneaux à médecine_.
=Botanical Origin=—_Prunus domestica_ L., var. ζ. _Juliana_ DC.—It is
from this tree, which is known as _Prunier de St. Julien_,[962] that
the true _Medicinal Prunes_ of English pharmacy are derived. The tree
is largely cultivated in the valley of the Loire in France, especially
about Bourgueil, a small town lying between Tours and Angers.
=History=—The plum-tree (_P. domestica_ L.) from which it is supposed
the numerous cultivated varieties have descended, is believed to occur
in a truly wild state in Greece, the south-eastern shores of the Black
Sea (Lazistan), the Caucasus, and the Elburz range in Northern Persia,
from some of which countries it was introduced into Europe long before
the Christian era. In the days of Pliny, numerous species of plum were
already in cultivation, one of which afforded a fruit having laxative
properties.
Dried prunes, especially those taking their name from Damascus (_Pruna
Damascena_), are frequently mentioned in the writings of the Greek
physicians, by whom as well as at a later period by the practitioners
of the Schola Salernitana, they were much employed.
[961] Gmelin, _Chemistry_, vii. 389; xv. 422.
[962] Loiseleur-Deslongchamps et Michel, _Nouveau Duhamel, ou Traité
des arbres et arbustes que l’on cultive en France_, v. (1812) 189, pl.
54. fig. 2, pl. 56. fig. 9.
In the older London pharmacopœias, many sorts of plum are enumerated,
but in the reformed editions of 1746, 1788, and 1809, the French Prune
(_Prunum Gallicum_) is specially ordered, its chief use being as an
ingredient of the well-known _Lenitive Electuary_; and this fruit
is still held by the grocers to be the legitimate _prune_. The same
variety is regarded in France as the prune of medicine.
=Description=—The prune in its fresh state is an ovoid drupe of a deep
purple hue, not depressed at the insertion of the stalk, and with
a scarcely visible suture, and no furrow. The pulp is greenish and
rather austere, unless the fruit is very ripe; it does not adhere to
the stone. The stone is short (⁷/₁₀ to ⁸/₁₀ of an inch long, ⁵/₁₀ to
⁶/₁₀ broad), broadly rounded at the upper end and slightly mucronulate,
narrowed somewhat stalk-like at the lower, and truncate; the ventral
suture is broader and thicker than the dorsal.
The fruit is dried partly by solar and partly by fire-heat, that is to
say, it is exposed alternately to the heat of an oven and to the open
air. Thus prepared, it is about 1¼ inches long, black and shrivelled,
but recovers its original size and form by digestion in warm water.
The dried pulp or sarcocarp is brown and tough, with an acidulous,
saccharine, fruity taste.
=Microscopic Structure=—The skin of the prune is formed of small,
densely packed cells, loaded with a dark solid substance; the pulp
consists of larger shrunken cells, containing a brownish amorphous mass
which is probably rich in sugar. This latter tissue is traversed by a
few thin fibro-vascular bundles, and exhibits here and there crystals
of oxalate of calcium. By perchloride of iron, the cell-walls, as well
as the contents of the cells, acquire a dingy greenish hue.
=Chemical Composition=—We are not aware of any analysis having been
made of the particular sort of plum under notice, nor that any attempt
has been made to discover the source of the medicinal property it is
reputed to possess. Some nearly allied varieties have been submitted
to analysis in the laboratory of Fresenius, and shown to contain
saccharine matters to the extent of 17 to 35 per cent., besides malic
acid, and albuminoid and pectic substances.[963]
=Uses=—The only pharmaceutical preparation of which the pulp of prunes
is an ingredient, is _Confectio Sennæ_, the _Electuarium lenitivum_ of
the old pharmacopœias. The fruit stewed and sweetened is often used as
a domestic laxative.
=Substitute=—When French prunes are scarce, a very similar fruit,
known in Germany as _Zwetschen_ or _Quetschen_, is imported as a
substitute.[964] It is the produce of a tree which most botanists
regard as a form of _Prunus domestica_ L., termed by De Candolle var.
_Pruneauliana_. K. Koch,[965] however, is decidedly of opinion that it
is a distinct species, and as such he has revived for it Borkhausen’s
name of _Prunus œconomica_. The tree is widely cultivated in Germany
for the sake of its fruit, which is used in the dried state as an
article of food, but is not grown in England.
[963] Liebig’s _Ann. der Chemie_, ci. (1857) 228.
[964] This was especially the case in the winter of 1873-74.
[965] _Dendrologie_, part i. (1869) 94.
The dried fruit differs slightly from the ordinary prune in being
rather larger and more elongated, and having a thicker skin; also
in the stone being flatter, narrower, pointed at either end, with
the ventral suture much more strongly curved than the dorsal. The
fruits seem rather more prone to become covered with a saccharine
efflorescence.