MICROCHEMISTR Y. 93 



coniferin presents a considerable number of color-reactions, 

 it has not yet been successfully recognized within the cells 

 by microchemical means. Yet the various reactions for 

 coniferin succeed easily with all lignified cell-membranes, 

 and it is usually assumed that they contain coniferin 

 <cf. 254-256). ' 



b. Datiscin, C 21 H 22 O 12 . 



152. Datiscin has been recognized microchemically by O. 

 Hermann (I, 9), especially in the cell-sap of the bark-paren- 

 chyma and as a deposit in the cell-walls of the thick-walled 

 cells of the wood and bark of Datisca cannabina. This 

 author used principally lime and baryta waters which give a 

 pure yellow solution with datiscin, and cause a deep yellow 

 coloring of all cells containing it ; while the addition of 

 acetic acid or dilute hydrochloric acid instantly causes the 

 color to disappear. Besides, datiscin gives yellow precipi- 

 tates with lead acetate or zinc chloride, a greenish one with cu- 

 pric salts, or a dark brownish-green one with ferric chloride. 



c. Frangulin, C 20 H 20 O ]0 . 



*53- Frangulin forms a yellow crystalline mass, which is 

 insoluble in water, but dissolves in alkalies with a cherry-red 

 -color. According to Borscow (I, 33), it occurs inside the 

 parenchymatous elements of the stem of Rhamnus frangula, 

 united with small starch-granules, which are colored blue by 

 a solution of iodine, and blood-red by caustic potash or 

 ammonia (?). , 



d. Hesperidin, C ai H 26 O 12 (or C 50 H 60 O 27 ?). 



154. Hesperidin is dissolved in the cell-sap within the 

 living plant ; but it is deposited, like inulin, in tissues which 

 have lain for some time in alcohol or glycerine, in the form 

 of sphaerocrystals. According to PfefTer (III), unripe 

 oranges are especially favorable objects for study. 



The sphaerocrystals of hesperidin are distinguished from 



