430 poisons : their effects and detection. [§§ 520 , 521 . 
XII. —Colchicine. 
§ 520. The whole of the Colchicum autumnale, or common meadow- 
saffron, is poisonous, owing to the presence of an alkaloid (discovered by 
Pelletier and Caventou) called Colchicine. 
According to Johannson’s experiments, the dried colchicum seeds 
contain 1*15 per cent, of colchicine ; the leaves, 1*459 per cent. ; the 
bulbs, from 1*4 to 1*58 per cent. ; and the roots, 0*634 per cent. The 
frequent poisoning of cattle in the autumn by colchicum, its use in 
quack pills for rheumatism, and its supposed occasional presence in 
beer, give it an analytical importance. 
§ 521. Colchicine (C 22 H 25 N0 6 ) may be extracted from the seeds, etc., 
in the manner recommended by Hiibler :—The seeds are treated, without 
crushing, by hot 90 per cent, alcohol, and the alcoholic solution evapo¬ 
rated to a syrup, which is diluted with twenty times its bulk of water 
and filtered; the liquid is next treated with acetate of lead, again filtered, 
and the lead thrown out by phosphate of soda. Colchicine is now pre¬ 
cipitated as a tannate. 1 The precipitation is best fractional, the first 
and last portions being rejected as containing impurities. The tan¬ 
nate is decomposed in the usual way with litharge and extracted by 
alcohol. 
A simpler method is, however, extraction by chloroform from an 
aqueous solution, feebly acidified, as recommended by Dragendorfi. 
The parts of the plant are digested in very dilute acid water, and the 
resulting solution concentrated and shaken up with chloroform, which is 
best done in a separating tube. 
half-choreic shocks or tremors ; the pupils dilate, and are alternately dilated and 
contracted. The heart’s action is increased or diminished in frequency ; sometimes 
there is vomiting, micturition, or defecation ; and there is always salivation. Finally, 
the central and peripheral temperatures are raised, and the excitability of the muscles 
and nerves becomes highly increased. With the native preparation of curare, it is 
impossible to prolong this stage, and symptoms of paralysis soon become associated 
with those of excitement. The choreic shocks were found to be arrested by section 
of the sciatic nerve. Other experiments proved that the spasms originated from the 
spinal cord, and were influenced by its preceding functional condition. If the cord 
was tied in the mid-dorsal region, and the curare injected, the spasms were still pro¬ 
duced m the hind legs ; but if, after the operation, the excitability of the posterior 
segment became lowered, the spasm was no longer produced in the hind legs. This 
dependence on a perfect functional activity is a point of difference of these spasms 
from those produced by strychnine, and by asphyxia. The action of small doses of 
curare is not, however, limited to the spinal cord. The diminished frequency of the 
heart continues after section of the pneumogastrics, and will even occur if the pneumo- 
gastrics have been previously divided. From these facts M. Couty considers that 
curare must not be regarded as entirely destitute of a “ convulsant ” action, nor of 
an action on the central nervous system. 
1 The purest tannic acid must be used. The commercial tannin may be purified 
by evaporating to dryness with litharge, exhausting the tannate of lead repeatedly 
with boiling alcohol and water, and, lastly, suspending in water, and separating the 
lead by SH 2 . 
