KOUSSO 63 



appearing under the lens as a brownish powder adhering to the 

 surface. The flowers are very numerous and shortly stalked. Each 

 bears on its pedicel two rounded bracts, and consists originally of 

 two whorls of greenish sepals, a caducous white corolla, abortive 

 stamens, and two monocarpellary ovaries enclosed in the tube of 

 the calyx. After fertilisation the inner sepals bend over the young 

 fruit and shrivel ; the outer grow larger and become deeply veined 

 with purple. Only one of the two ovaries arrives at matuiity. In 

 the drug the most conspicuous part of the flower is the outer whorl 

 of reddish, veined sepals ; in its centre may be found the inner sepals 

 bending over the immature fruit ; of corolla and abortive stamens 

 no trace is to be found. 



Kousso has no marked odour, but possesses a bitter, acrid taste. 



The student should soak a little kousso in water and, when 

 thoroughly softened, examine it with the help of lens and dissecting 

 needles. The two whorls of sepals and the young fruit can then be 

 distinguished without difficulty. 



The drug is easily identified, but the student should particularly 

 observe 



(a) The inner whorl of sepals bending over the young fruit, 

 (6) The enlarged, veined, outer whorl of sepals, 

 (c) The reddish colour of the drug, 



as these characters serve to distinguish the pistillate flowers, which 

 alone are official, from the staminate. 



Constituents. The most important constituent of kousso is koso- 

 toxin (Leichsenring, 1894), a highly active, amorphous, yellowish 

 substance, of which 0*004 gin. is sufficient to kill a frog. Protokosin 

 and kosidin are inactive, colourless, crystalline substances ; a- and 

 /3-kosin are inactive, yellowish, crystalline substances and appear to 

 be decomposition products, it being uncertain whether they occur 

 preformed in the drug. Kousso also contains tannin and resin, and 

 yields about 5 per cent, of ash. 



Kosotoxin is insoluble in water but easily soluble in, alcohol, ether, acetone, 

 chloroform, &c., as well as in solutions of alkaline carbonates. Caustic alkalies 

 convert it into "kosin. By the action of zinc dust and caustic soda kosin and 

 trimethylphloroglucin are obtained ; this reaction indicates a close relationship 

 with the vermifuge constituents of male fern and kamala, which under similar 

 conditions yield trimethylphloroglucin and dimethylphloroglucin respectively. 



Protokosin occurs in colourless needles melting at 176, a-kosin, in yellowish 

 needles melting at 161, and /2-kosin, in dark yellow prisms melting at 121. 



Substitutions &c. Under the name of ' loose kousso ' the flowers 

 stripped from the panicles and dried are sometimes imported. They 

 arrive usually in more or less fragmentary condition, and frequently 

 contain a considerable admixture of staminate flowers. These may 



