80 PHYSOSTIGMA VENENOSUM 



mass, of a brown colour, readily soluble in alcohol, ether, and 

 acids, but less so in water. Its watery solution has an alkaline 

 reaction ; and on exposure to the air soon becomes red or some- 

 times blue, from a partial decomposition of the alkaloid. As 

 subsequently obtained by Hesse, it was perfectly colourless and 

 tasteless, and on exposure to a temperature of 212 it reddened, 

 owing to decomposition commencing. In 1865, Vee and Leven, 

 by operating in essentially the same manner as Hesse, obtained an 

 alkaloid in the form of colourless, rhomboidal, tabular crystals, 

 having a bitter taste, but agreeing in most other respects with 

 the physostigmia, as just described. These chemists called this 

 substance eserin. Tison and other chemists regard eserin or eseria 

 as pure physostigmia ; but Fliickiger and Hanbury remark that 

 " at present we feel hardly warranted in admitting the identity 

 of the two substances." The activity of eseria or physostigmia ? 

 is indicated by the fact that if a single drop of a solution con- 

 taining only 1 part in 1 000, be placed within the eyelids, it causes 

 great and lasting contraction of the pupil. A peculiarity of the 

 alkaloid, according to Yee is, that if to its solution in water a little 

 potash, lime, or soda be added, a red coloration is produced, 

 which rapidly becomes more intense. The colour is not, however, 

 permanent, but gradually passes into yellow, green, and blue. 

 The same property is also said to be possessed by the alcoholic 

 extract of Calabar bean. 



Medical Properties and Uses. From the experiments of Dr 

 Fraser and others, it has been proved that Calabar bean is a 

 powerful sedative of the spinal cord, producing in over- doses 

 paralysis of the lower extremities and death by asphyxia, or in 

 still larger doses, death by paralysis of the heart. When applied 

 locally to the eye, it rapidly induces contraction of the pupil. 

 The principal use of the Calabar bean is as a local application to 

 the eye, to cause contraction of the pupil, in certain diseases and 

 injuries of that organ. It has also been given internally in small 

 doses, and with some benefit, in tetanus, chorea, epilepsy, and 

 other nervous affections ; also in the treatment of strychnia 

 poisoning, general paralysis of the insane, and other affections. 



