_Colchicum Seed_; F. _Semence de Colchique_; G. _Zeitlosensamen_.
=Botanical Origin=—_Colchicum autumnale_ L., see page 699. The inflated
capsule, which grows up in the spring after the disappearance of the
flower in the autumn, is three-celled, dehiscent towards the apex by
its ventral sutures, and contains, attached to the inner angle of the
carpels, numerous globular seeds, which arrive at maturity in the
latter part of the summer.
=History=—Colchicum seeds were introduced into medical practice by Dr.
W. H. Williams, of Ipswich, about 1820, on the ground of their being
more certain in action than the corm.[2621] They were admitted to the
London Pharmacopœia in 1824.
=Description=—The seeds are of globose form, about ⅒ of an inch in
diameter, somewhat pointed by a strophiole, which when dry is not
very evident. They are rather rough and dull; when recent of a pale
brown, but become darker by drying, and at the same time exude a sort
of saccharine matter. They are inodorous even when fresh, but have a
bitter acrid taste; they are very hard and difficult to powder.
=Microscopic Structure=—The reticulated, brown coat of the seed
consists of a few rows of large, thin-walled tangentially-extended
cells, considerably smaller towards the interior, the outermost
containing starch grains in small number. The thin testa is closely
adherent to the horny greyish albumen. The cells of the latter are
remarkable for their thick walls, showing wide pores; they contain
granular plasma and oil-drops. The very small leafless embryo may be
observed on transverse section close beneath the testa on the side
opposite the strophiole.
=Chemical Composition=—The active principle of colchicum seed is
termed _Colchicin_, but the chemists who have made it the subject
of investigation are not agreed as to its properties. Thus Oberlin
(1856) showed it to contain nitrogen, but without possessing basic
properties. By treatment with acids, the amorphous colchicin yields a
crystallizable body, _Colchiceïn_. Hübler (1864) prepared colchicin
in the same way by which the so-called “bitter principles,” like
dulcamarin (p. 451) are obtainable. He assigned to colchiceïn acid
qualities and, strangely enough, the same formula he gave for colchicin
itself, namely C₁₇H₁₉NO₅. Maisch[2622] as well as Diehl[2623] again
obtained discrepant results. _Colchicin_ of definite composition has
not yet been isolated.
[2621] _London Medical Repository_, Aug. 1, 1820.
[2622] _Pharm. Journ._ ix. (1867) 249.
[2623] _Proc. Americ. Pharm. Assoc._ 1867. 363.
It would appear that in an aqueous or alcoholic extract of the seed
an extremely small amount of an alkaloid is present, but that a basic
substance is immediately formed on addition of mineral acids, or
also oxalic acid. This suggestion is to some extent supported by the
following facts:—
By adding the usual test solution for alkaloids, _i.e._ iodohydrogyrate
of potassium (50 grammes of iodide of potassium, 13·5 of perchloride of
mercury in one litre), to an aqueous solution of an alcoholic extract
of the seeds, a very slight turbidity, or an insignificant precipitate
is observed. Yet on addition of sulphuric, or nitric, or hydrochloric
acid, an abundant precipitate of a beautiful yellow is at once
produced. This experiment succeeds with a few seeds, either entire or
powdered; it may be conveniently applied for the detection of colchicum
in any preparation. We have ascertained that the yellow precipitate
can be obtained also with the other parts of the plant. If the yellow
compound is decomposed by sulphuretted hydrogen, the filtrate, after
due concentration, now precipitates immediately on addition of the
iodohydrogyrate, yet still more abundantly in presence of a mineral
acid.
The seeds contain traces of gallic acid, much sugar and fatty oil. Of
the last we obtained 6·6 per cent. by exhausting the dried seed with
ether. The oil concreted at -8° C. Rosenwasser (1877) obtained 8·4 per
cent. of the oil.
=Uses=—The same as those of the corm.