PHYSOSTIGMA. CALABAR BEAN, 24I 



The almond itself consists of two cotyledons closely 

 appressed, surrounded by a thin brown layer of paren- 

 chyma tic tissue, with numerous fine vessel bundles 

 ramifying over the surface ; this layer is readily removed 

 by soaking the seed. 



Histology. — The outer' layer of cells, the endocarp, 

 consists of a number of layers, the outer ones of 

 which are brown, flattened. These are often irregular 

 because of the fine vessels that pass into the tissue of 

 the endocarp. Calcium oxalate crystal sacs are also 

 found. 



The inner layers are made up of small colorless cells 

 whose outer walls are somewhat swollen and form a sort 

 of interlacing with the inner cells of the exocarp. The 

 inner face of the endocarp is united but slightly with the 

 cells of the cotyledons. 



The cotyledons consist of numerous parenchymatic 

 cells which are smaller and more regular at the periphery 

 and increase in size and irregularity toward the centre. 

 The cells contain numerous oil globules and also aleurone 

 grains. Starch is lacking. 



Chemistry. — Over one-half the weight of the seed 

 consists of a clear yellowish oil, mild tasting, sp. gr. 

 0.920°. It consists for the main part of the glycerine 

 ether of oleic acid, CgoH5^02, also probably a number of the 

 fatty acids found in Linum. A small amount of sugar 

 (glucose) is also found. This with mucilaginous ma- 

 terials makes up about 7 per cent. 



PHYSOSTIGMA. CALABAR BEAN. 



Physostigma is the seed of Physostigma venenosum 

 (Balfour) , a member of the PapilionacecB. It is a climbing 

 shrub, sometimes 16 m. high, a native of the delta of the 

 Niger and the Guinea Coast. Cultivation has proved 

 successful.' 



A so-called Calabar Bean comes into European markets 



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