422 APOCYNE^. 



spots ; the interior substance and inner surface (liber) is of a bright 

 buff, A transverse section shows the liber to be finely marked by 

 numerous small medullary rays. The bark is almost inodorous; its 

 taste is purely bitter and neither aromatic nor acrid. 



Microscopic Structure — The cortical tissue is covered with a thin 

 suberous coat ; the middle layer of the bark is built up of a thin walled 

 parenchyme, through which enormous, hard, thick- walled cells are scat- 

 tered in great numbers and are visible to the naked eye, as they form 

 large irregular groups of a bright yellow colour. Towards the inner part 

 these stone-cells disappear, the tissue being traversed by undulated 

 medullary rays, loaded with very small starch grains ; many of the other 

 parenchymatous cells of the liber contain crystals of calcium oxalate. 

 The longitudinal section of the liber exhibits large but not very 

 numerous laticiferous vessels, containing a brownish mass, the concrete 

 milk-juice in which all parts of the tree abound. 



Chemical Composition — The first attempts to isolate the active 

 principles of this bark were made by two apothecaries, Scharl^e at 

 Batavia' (1862) and Gruppe at Manila^ (1872). 



In 1875 Jobst and Hesse exhausted the powdered bark with 

 petroleum ether, and then extracted, by boiling alcohol, the salt of an 

 alkaloid, which they called Ditamine. After the evaporation of the 

 alcohol, it is precipitated by carbonate of sodium and dissolved by 

 ether,, from which it is removed by shaking it with acetic acid. 

 Ditamine as again isolated from the acetate forms an amorphous and 

 somewhat crystalline, bitterish powder of decidedly alkaline character ; 

 the barks yields about 0'02 per cent, of it. 



From the substances extracted by means of petroleum ether, as 

 above stated, Jobst and Hesse further isolated (1) Echicaoutchin, 

 Q23jj40Q2^ an amorphous yellowish mass ; (2) Echicerin, C^H^O", forming 

 acicular crystals, melting at 157° C; (3) Echitin, C^^H^-0^, crystallized 

 scales, melting at 170" ; (4) Echitevn, C^^jjTooa^ which forms rhombic 

 prisms, melting at 195° ; (5) Echiretin, C^H'^C, an amorphous 

 substance melting at 52° C. 



Echicaoutchin may be written thus : (C'H')'O', echicerin (C'ff)'O'-^, 

 echiretin (C^H^yO^; these formulae at once point out how nearly the 

 three last named substances are allied. They are probably constituents 

 of the milky-juice of the tree. 



Lastly, Jobst and Hesse pointed out the existence of another 

 alkaloid in Dita bark. 



Hamack (1877) on the other hand is of the opinion that it contains 

 only one alkaloid, which he terms Ditaine. He used the alcoholic 

 extract of the bark which he treated with ether to which he added a 

 little ammonia. By this process ditamine of Jobst and Hesse would 

 have been removed, but Hamack suggests that only a little ditaine 

 is dissolved by ether. He then mixed the extract with potash and 

 exhausted it with alcohol, which afforded crystals of ditaine, answering 

 to the formula C^^H^^^N^O^ ; its physiological action is nearly the same 

 as that of curare. Ditaine is but sparingly soluble in ether or petro- 



^GeneeBk,Tijd8chr.Nederl.Indie,x.(\8&Z) ^ Jahresbericht of Wiggers and Hiise- 



200; also Archiv der Phammcie, 212 (1878) mann, 1873, 51, 

 439. 



