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Composition. Besides the ordinary constituents of beans, the 

 seed of physostigma contains an active principle, phttsostigmin. 

 or eserin, C^H^ISLC^, an alkaloid, combining with acids, and 

 variously obtained as colourless crystals, or an amorphous or 

 syrupy body. 



Dose, in powder. 1 to 4 gr. 



Preparation. 



Extractum Physostigmatis. Spirituous. 45 in 1. Dose, 

 is to i gr. 



1. IMMEDIATE LOCAL ACTION AND USES. 



Extract of physostigma or preparations of eserine are 

 readily absorbed by the conjunctiva, and produce the specific 

 contraction of the pupil to be presently noticed. 



Taken by the mouth, calabar bean in moderate doses 

 sometimes causes sickness and colic, and in larger doses diarrhoea, 

 all from increased and irregular peristalsis, apparently of local 

 origin. The extract is therefore occasionally used in habitual 

 constipation. 



2. ACTION IN THE BLOOD. 



Eserin enters the blood unchanged, and passes thence into 

 the tissues. 



3. SPECIFIC ACTION AND USES. 



Eserin is found in all the organs. Along with the gastro- 

 intestinal sjTnptoms first described, moderate doses of the bean 

 give rise to a sense of weakness, faintness, and shortness of 

 breath ; larger doses to an aggravation of the same symptoms, 

 with contraction of the pupil, frontal headache, salivation, 

 diaphoresis, slowing and weakening of the pulse. These are 

 short of truly poisonous effects. 



On analysis it is found that consciousness is not lost, 

 though impaired by large doses, showing comparative freedom 

 of the convolutions. The cord is the part principally affected by 

 calabar bean, the chief symptoms being of the nature of motor 

 jura lysis from depression of the anterior cornua, and thus of 

 reflex irritability also. The respiratory muscles necessarily 

 fail from this cause. The posterior cornua (sensory portions) 

 of the cord are paralysed to a degree, so that sensibility is 

 diminished in the limbs. The motor nerves and muscles are but 

 slightly affected directly. Occasional twitchings occur, whether 

 direct or spinal in origin. The sensory nerves are not directly in- 

 fluenced. The medulla is decidedly affected by physostigma. 

 Thus the respiratory centre, after brief (probably reflex) stimu- 

 lation, is depressed, and death occurs chiefly by asphyxia. The 



