_Semen Crotonis_; _Croton Seeds_; F. _Graines de Tilly ou des
Moluques_, _Petits Pignons d’Inde_; G. _Purgirkörner_, _Granatill_.
=Botanical Origin=—_Croton Tiglium_[2095] L. (_Tiglium officinale_
Klotzsch), a small tree, 15 to 20 feet high, indigenous to the Malabar
Coast and Tavoy, cultivated in gardens in many parts of the East, from
Mauritius to the India Archipelago. The tree has small inconspicuous
flowers, and brown, capsular, three-celled fruits, each cell containing
one seed. The leaves have a disagreeable smell and nauseous taste.
=History=—In Europe, the seeds and wood of the tree were first
described in 1578 by Christoval Acosta—the former, with a figure of the
plant, appearing under the name of _Piñones de Maluco_.[2096] The plant
was also described and figured by Rheede (1679)[2097] and Rumphius
(1743).[2098] The seeds, which were officinal in the 17th century, but
had become obsolete, were recommended about 1812 by English medical
officers in India,[2099] and the expressed oil by Perry, Frost, Conwell
and others about 1821-24. The oil then in use was imported from India,
and was often of doubtful purity, so that some druggists felt it
necessary to press the seeds for themselves.[2100]
[2095] Fig. in Bentley and Trimen’s _Medic. Plants_, part 1 (1875).
[2096] _Tractado_, etc., Burgos, 1578. c. 48.—After speaking of the
virtues of the seeds, he adds—“tambien las buenas mugeres de aquellas
partes, amigas de sus maridos, les dă hasta quatro destos por la boca,
para embiar a los pobretos al otro mundo”!
[2097] _Hortus Malabaricus_, ii. tab. 33.
[2098] _Herbarium Amboinense_, iv. tab. 42.
[2099] Ainslie, Mat. _Med. of Hindoostan_, 1813. 292.
[2100] The oil was very expensive. I find by the books of Messrs. Allen
and Hanburys, that the seeds cost in 1824, 10s., and in 1827, 18s. per
lb. The oil was purchased in 1826 by the same house at 8_s._ to 10_s._
per ounce.—D. H.
=Description=—Croton seeds are about half an inch long, by nearly ⅖ of
an inch broad, ovoid or bluntly oblong, divided longitudinally into
two unequal parts, of which the more arched constitutes the dorsal
and the flatter the ventral side. From the hilum, a fine raised line
(raphe) passes to the other end of the seed, terminating in a darker
point, indicating the chalaza. The surface of the seed is more or less
covered with a bright cinnamon-brown coat, which when scraped shows the
thin, brittle, black testa filled with a whitish, oily kernel, invested
with a delicate seed-coat. The kernel is easily split into two halves
consisting of oily albumen, between which lie the large, veined, leafy
cotyledons and the radicle. The taste of the seed is at first merely
oleaginous, but soon becomes unpleasantly and persistently acrid.
=Microscopic Structure=—The testa consists of an outer layer of
radially arranged, much elongated and thick-walled cells; the inner
parenchymatous layer contains small vascular bundles. The soft tissue
of the albumen is loaded with drops of fatty oil. If this is removed
by means of ether and weak potash lye, there remain small granules of
albuminoid matter, the so-called _Aleuron_, and crystals of oxalate of
calcium.
=Chemical Composition=—The principal constituent of croton seeds is the
fatty oil, the _Oleum Crotonis_ or _Oleum Tiglii_ of pharmacy of which
the kernels afford from 50 to 60 per cent. That used in England is for
the most part expressed in London, and justly regarded as more reliable
than that imported from India, with which the market was formerly
supplied. It is a transparent, sherry-coloured, viscid liquid, slightly
fluorescent, and having a slight rancid smell and an oily, acrid taste.
Its solubility in alcohol (·794) appears to depend in great measure on
the age of the oil, and the greater or less freshness of the seeds from
which it was expressed,—oxidized or resinified oil dissolving the most
readily.[2101] We found the oil which one of us had extracted by means
of bisulphide of carbon to be levogyre.
Croton oil consists chiefly of the glycerinic ethers of the common
fatty acids, such as stearic, palmitic, myristic and lauric acids. They
partly separate in the cold; the acids also may partly be obtained by
passing nitrous acid through croton oil. There are also present in the
latter, in the form of glycerinic ethers, the more volatile acids, as
formic, acetic, isobutyric and one of the valerianic acids.[2102] The
volatile part of the acids yielded by croton oil contains moreover an
acid which was regarded by Schlippe (1858) as angelic acid, C₅H₈O₂.
Yet in 1869 it was shown by Geuther and Frölich to be a peculiar
acid, which they called _Tiglinic acid_. Its composition answers to
the same formula, C₄H₇COOH, as that of angelic acid; but the melting
points (angelic acid 45°, tiglinic 64° C.) and boiling points (angelic
acid 185°, tiglinic 198°·5) are different. Both these acids have been
mentioned in our article on Flores Anthemidis, at page 386. Tiglinic
acid may also be obtained artificially; it is the methylcrotonic acid
of Frankland and Duppa (1865).
Schlippe also stated croton oil to afford a peculiar liquid acid termed
_Crotonic Acid_, C₄H₆O₂. According to Geuther and Frölich, however, an
acid of this formula does not occur at all in croton oil. By synthetic
methods three different acids of that composition are obtainable.
The _drastic principle_ of croton oil has not yet been isolated.
Buchheim[2103] suggested that the action of the oil depends
upon “_Crotonoleic acid_,” which however he failed in isolating
satisfactorily. It is remarkable that the wood and leaves of _Croton
Tiglium_ appear to partake also of the drastic properties of the seeds.
Schlippe asserts that he has separated the _vesicating matter_ of
croton oil: if the oil be agitated with alcoholic soda, and afterwards
with water, the supernatant liquor will be found free from acridity,
while the alcoholic solution will yield, on addition of hydrochloric
acid, a small quantity of a dark brown oil, called _Crotonol_,
possessing vesicating properties. We have not succeeded in obtaining
it, nor, so far as we know, has any other chemist except its discoverer.
The shells of the seeds (testa) yield upon incineration 2·6 per cent.
of ash; the kernels dried at 100° C. 3·0 per cent.
=Commerce=—The shipments of croton seeds arrive chiefly from Cochin or
Bombay, packed in cases, bales or robbins; but there are no statistics
to show the extent of the trade.
[2101] Warrington, _Pharm. Journ._ vi. (1865) 382-387.
[2102] Schmidt and Berendes, 1878.
[2103] In the _Jahresbericht_ of Wiggers and Husemann, 1873. 560.
=Uses=—Croton seeds are not administered. The oil is given internally
as a powerful cathartic, and is applied externally as a rubefacient.
=Substitutes=—The seeds of _Croton Pavanæ_ Hamilton, a native of Ava
and Camrup (Assam), and those of _C. oblongifolius_ Roxb., a small
tree common about Calcutta, are said to resemble those of _C. Tiglium_
L., but we have not compared them. Those of _Baliospermum montanum_
Müll. Arg. (_Croton polyandrus_ Roxb.) partake of the nature of croton
seeds, and according to Roxburgh are used by the natives of India as a
purgative.