BARKS. 155 



pterocarpin. Santalin, CijHj^Oj or Ci^HjqOq, crystallizes 

 in minute red prisms, insoluble in water, dissolving in 

 alcohol with a red color and an acid reaction, in ether 

 with a yellowish and in alkalies with a violet color. 

 Pterocarpin, Cj^Hj^O^, colorless crystals, insoluble in 

 water, with difficulty in alcohol, easily in chloroform and 

 carbon disulphide. Soluble in concentrated sulphuric 

 acid with a red,* in nitric acid with a green, color. San- 

 tal, CgHgOg, colorless crystals, insoluble in water, with 

 difficulty in ammonia water and dilute alcohol, easily in a 

 weak solution of potash with at first a red and then a 

 green color. Ferric chloride turns the alcoholic solution 

 red. Concentrated sulphuric acid dissolves the crystals 

 with a red, nitric acid with a green, color. Homoptero- 

 carpin, colorless crystals, soluble in carbon disulphide. 



BARKS. 



The subject of barks in pharmacognosy is a much 

 abused one. The vegetable anatomist has one definition 

 of a bark, whereas the pharmacognocist has another. 

 To the one it consists of tissues developed in the main 

 from the layer of primary tissue termed the derma togen, 

 and comes to be entirely outside of what is known as the 

 phloem portion of the fibro- vascular bundles. To the 

 other, who does not restrict the term so closely, the 

 bark consists of all those structures outside of the cam- 

 bium line; in this sense, then, being a wider term than 

 that of the anatomist, including both phloem structures 

 and those in the bark proper. Hence the pharmacogno- 

 cist can rely in great part for the detection of the barks 

 upon the bast fibres, which, according to the anatomical 

 definition, have no place in the bark. The description of 

 the general type of barks here adopted will include both 

 definitions. 



In the growing stem anatomists have defined three 



