BOTANIC MATERIA MEDICA, 275 
hard, but very brittle, and of a pale chocolate 
color; the hilum is in a groove, which extends 
along the entire length of convex edge of the 
seed, and ending in the micropyle at one end 
and the chalza at the other; the seed is made up 
of two cotyledons, which are hard and white, 
between which is the embryo, with its short and 
curved radicle. The seeds have little or no 
odor, but the taste is of the bean-like character, 
and other edible leguminous seeds. Thekernel 
of the bean contains about 48 per cent of starch, 
23 per cent of /egumin, % per cent of oil, some 
mucilage, sugar, and anactive principle variously 
termed physostigmine, or eserine, calabarine or 
eseridine reputed to antagonize eserine. This 
latter constituent isan amorphous, colorless and 
tasteless substance, of an alkaline reaction, sol- 
uble in alcohol, ether, chloroform, and to some 
extent soluble in water; it is very poisonous, 
and has the power to contract the pupil of the 
eye. The medical effects of the physostigma, 
and its active principle, are powerfully sedative, 
having the power to contract the pupil of the 
eye. The officinal preparations are the tincture 
solid extract, and salicylate. The dose of the 
tincture, 2 to 4 drops; of the alcoholic extract, 
from 1-16 to 4 of a grain (0.004-0.01 gram), 
whilst the dose of eserina, 1-640fagrain. The 
seed is known technically as the physostigma 
faba, and called in Africa esere, and used by the 
natives as an ordeal poison. The name is de- 
rived from the peculiar character of its hooded 
stigma. 
