328 SCIENTIFIC AND APPLIED PHARMACOGNOSY 



then shipped to Ciudad, Venezuela, or Trinidad, where they are 

 steeped in rum or other alcoholic liquors and by a process of fermenta- 

 tion the fragrant principle, coumarin, is developed. The seeds are 

 removed and dried, when there forms upon the seed-coats the crys- 

 tallized coumarin. There are two principal varieties: (1) Dutch 

 Tonka obtained from Coumarouna odorata, growing in the northern 

 part of the Amazon region, and (2) English Tonka from C. oppositi- 

 folia of northern Brazil and Guiana. 



Description. Oblong-ovoid, somewhat flattened, 3 to 4 cm. in 

 length and about 1 cm. in width, externally nearly black, usually 

 covered with crystals of coumarin, the coriaceous testa being deeply 

 wrinkled; internally yellowish-brown, consisting of two plano- 

 convex cotyledons, enclosing a plumule with two pinnately compound 

 leaves and a fleshy radicle which is directed towards the micropyle 

 situated at the rounded end of the seed; odor fragrant; taste aro- 

 matic and somewhat pungent. 



Inner Structure. The easily separable seed-coat contains an 

 outer epidermal layer of stone cells, which possess rather porous, 

 somewhat thickened walls and a brownish-red or brownish-black 

 content ; a layer of spindle-shaped cells which are more or less undu- 

 lated in outline and unequal in thickness; a layer of parenchyma of 

 tangentially elongated compressed cells, interspersed with vascular 

 bundles; an inner epidermis of thin-walled rectangular cells with a 

 brownish content; perisperm made up of cells containing aleurone 

 grains; an endosperm of thin-walled cells; the cotyledons of poly- 

 hedral, thin-walled parenchyma containing an oily cytoplasm, 

 numerous starch grains and aleurone grains. 



Powder. Brownish-black; the parenchyma cells of the cotyle- 

 dons with numerous spheroidal starch grains from 0.004 to 0.010 mm. 

 in diameter; large, irregular aleurone grains from 0.020 to 0.035 mm. 

 in length, and considerable fixed oil. The easily separable seed-coat 

 contains rather characteristic stone cells, which on surface view are 

 polygonal and possess rather porous, somewhat thickened walls and 

 brownish-red or brownish-black contents. Beneath the stone cells 

 is a layer of broad, spindle-shaped cells with rather thick walls and 

 numerous intercellular spaces. 



Constituents. From 1 to 10 per cent of coumarin, which crys- 

 tallizes in various forms (Fig. 59), having a characteristic aromatic 

 odor and a bitter taste. It is apparently developed from a mother 

 substance contained in the fixed oil. The latter occurs to the extent 

 of about 25 per cent. The seeds also contain starch, sitosterin, stig- 

 masterin, sugar and gum. Ash from 3 to 4 per cent. 



