CALABAR BEAN 511 



may be cautiously and gradually increased, until slight 

 muscular twitchings are produced. Tablets and lamellae 

 containing ^th and T tyoth gr. of strychnine sulphate are 

 convenient for hypodermic injections. Strychnine arsenite 

 has been recommended in some of the Continental 

 veterinary schools for the treatment of persistent nasal 

 discharges. 



CALABAR BEAN 



PHYSOSTIGMATIS SEMINA. The ripe seeds of Physostigma 

 venenosum. Nat. Ord. Leguminosae. 



PHYSOSTIGMIN^E SULPHAS. (C 15 H 21 N 3 2 ) 2 , H 2 S0 4 , zH 2 O. 

 Eserine Sulphate. The sulphate of an alkaloid obtained 

 from Calabar bean. Western Africa (B.P.). 



Calabar bean is a large reddish-brown, oblong, reniform 

 seed, usually about an inch long, three-quarter inch broad, 

 and half an inch thick. The testa, hard, thick, and rough, 

 encloses two cotyledons, between which there is a large 

 cavity. The bean has no characteristic taste, and no 

 odour (B.P.). Its activity depends upon the presence of 

 two alkaloids (1) Physostigmine or Eserine, occurring in 

 colourless crystals, soluble in alcohol, benzol, chloroform, 

 and diluted acids, and partially in water. It paralyses 

 nerve centres, and stimulates muscular fibre. (2) Cala- 

 barine, soluble in water and alcohol, but not in ether. It 

 causes strychnine-like convulsions. 



Eserine Sulphate occurs in yellowish- white minute crystals, 

 becoming red by exposure to air and light, having a bitter 

 taste, highly deliquescent, very soluble in water and in 

 alcohol (90 per cent.). The aqueous solution is neutral to 

 litmus, and, applied to the eye, causes contraction of the 

 pupil. Eserine sulphate contains about 70 per cent, of the 

 alkaloid. Solutions keep better when mixed with a grain 

 or two of salicylic acid. 



GENERAL ACTIONS. Calabar bean and its chief alkaloid 

 stimulate motor nerve-endings supplying voluntary and 

 involuntary muscles, but depress the central nervous system. 

 Eserine exerts no topical action on the skin or mucous 



