1895.] its Natural History, CJiemistry, and Pharmacology. 71 



of Strophanthus seeds, its physical and chemical properties enabled the 

 conclusions to be drawn that the poison was not made from these 

 seeds, but was chiefly composed of an extract prepared from a wood. 

 These conclusions have been confirmed by the examination of further 

 specimens of the Wa Nyika arrow-poison, and of the wood from 

 which it is prepared. 



Specimens of the Wa Gyriama and of the Wa Kamba arrow-poisons 

 and of the wood from which they are prepared have also been 

 examined. 



We have been enabled to refer all these specimens of wood to the 

 geuus Acokanthera, which, therefore, supplies the arrow-poison used 

 over an extensive area in East Africa. 



Leaves, flowers, and fruit, each taken from the same individual 

 tree, having also been sent to us, we have been enabled to determine 

 that the wood of the species Acokanthera Schimperi, Benth. and Hook. 

 (Garissa Schimperi, A.DC.), is used by the Wa Nyika and the Wa 

 Gyriama and other tribes in preparing their arrow-poison. 



The tribes inhabiting the coast regions near Mombasa have long 

 been known to use an arrow-poison, but the botanical specimens 

 received by us are apparently the first that have been completely 

 identified. 



The arrow-poison of these tribes usually contains a crystalline 

 glucosidal active principle, which, in its chemical properties and 

 pharmacological action, is identical with the active principle also 

 separated by us from the wood of Acokanthera Schimperi. 



This active principle crystallises from water in the form of colonr- 

 less, transparent, quadrangular plates, and from alcohol in colourless, 

 thin, needle-shaped crystals, which usually group themselves in tufts 

 and rosettes. At a temperature of 13 15 C. it is soluble to the 

 extent of O93 per cent, in distilled water, and of 2'4 per cent, in 

 diluted alcohol of sp. gr. 0'920. At higher temperatures much 

 larger quantities are dissolved by water and by alcohol. It is alto- 

 gether insoluble in ethylic ether and in chloroform. A saturated 

 solution in cold water is tasteless and neutral in reaction, and is 

 affected, in an obvious manner, by very few chemical reagents. 

 Strong sulphuric acid produces immediately a red colour, and subse- 

 quently a green colour is developed. The melting point is about 

 186 C. When treated with dilute sulphuric acid it gives the 

 reaction of a glucoside. 



Concordant combustions made for us by Dr. Dobbin of the 

 Chemical Laboratory of the University show that, dried at 100 C., 

 it contains (ii) C 58'46 per cent., H 7'71 per cent., which corresponds 

 with the formula CsuH^Ois. 



In 1832 MM. Rochebraune and Arnaud separated an amorphous 

 glncoside from the root of an unknown species of tree used in North 



VOL. LVIII. o 



