80 PHYSOSTIGMA VENENOSUM 



Official Part and Names. PHYSOSTIGMATIS FABA ; the seed 

 (B. P.). The seeds (Physostigmatis Semina) (I. P.). PHYSO- 

 STIGMA; the seed (U. S. P.). 



General Characters and Composition. These seeds, which are 



commonly known as Calabar Beans, are imported from Western 



Africa. They are about the size of a very large horse bean, 



averaging from 1 to 1J inch long, f of an inch broad, and 65 



grains in weight. In shape they are somewhat reniform, being 



straight or slightly concave on one side, and convex on the other. 



The convex side is marked by a long, broad, black furrow (hilum), 



with raised edges, which terminates in a small depression or 



aperture (micropyle) near one end. The furrow is also traversed 



from end to end by a central raised line, which corresponds to 



the raphe. The seeds are covered by a hard, brittle, somewhat 



rough, shining integument or testa, which is commonly of a deep 



chocolate-brown colour, except on the raised edges of the furrow, 



where the tint is lighter. In some cases, however, the colour of 



the seeds is brownish-red or ash-grey. The nucleus or kernel 



principally consists of two hard, white, brittle, cotyledons, closely 



adherent to the testa, and separated from each other by a largish 



cavity. The seeds have no marked taste, simply that of an 



ordinary bean, and no odour. They yield their virtues entirely 



to alcohol, and imperfectly to water. The characters of Calabar 



beans are so marked, that they may be readily distinguished from 



all other seeds which may be mixed with them. We have 



frequently so noticed the seeds of a species of Mucuna ; and 



others, have also detected those of the Oil Palm (Elais guine- 



ensis) . 



Calabar beans contain about 48 per cent, of starch, 23 per 

 cent, of albuminous matter, a little fatty oil, mucilage, sugar, 

 and other unimportant ingredients, and a peculiar alkaloid on 

 which their activity depends. This was discovered in 1863 by 

 Jobst and Hesse, and named physostigmin ; it is principally 

 contained in the kernel, but as shown by Fraser, the shells are 

 not devoid of active principle. The physostigmia or physo- 

 stigmin as thus found by Jobst and Hesse is an amorphous 



