352 MICROCHEMISTRY OF PJANT PRODUCTS 



by the action of diastase. Maltose reduces Fehling's solution, 

 but only about two-thirds as much as does grape-sugar (dex- 

 trose, glucose.) 



Morphine, C^^HuNOj-l-HjO.— This was the first alka- 

 loid to be extracted pure and studied. It is the chief alkaloid 

 in opium obtained from the latex ,of Papaver somniferum. 

 When the latex .containing morphine is treated with potassium 

 iodide-iodine, a reddish-brown precipitate is produced, with po- 

 tassium-bismuth iodide a reddish-orange, and with potassium- 

 mercuric iodide a yellowish- white, precipitate, while phospho- 

 molybdic acid produces a yellow precipitate. A solution of 

 5 drops of methylal in i c.c. of concentrated sulphuric acid gives 

 a violet color to latex containing morphine. Codeine, C^gHji- 

 NO3, associated with morphine in opium, has essentially the 

 same color reactions. On treating opium infusion with ammonia, 

 morphine is precipitated and codeine is left in solution. 



Mucilages (see also under Gums). — Mucilage contained in 

 sections of plant tissues may be differentiated by staining with 

 methylene-blue. Place the sections in a deep blue solution of 

 methylene-blue in equal parts of alcohol, glycerine, and water. 

 This operation may be done on the glass slide. The staining 

 will soon be completed and the sections will then be ready for 

 examination under a coverglass. If the sections are taken 

 from fresh materials, the razor should be moistened with alcohol. 

 Dry materials should be soaked in water to soften for cutting. 

 If it is found that the mucilage dissolves too much in the water, 

 the mucilage may be hardened and the tissues softened at the 

 same time in the lead acetate solution described under Gums. 



Mustard Oil, C3H5CNS. — Seeds and the vegetative organs 

 of the Cruciferae, Resedacese, Capparidaceae, Tropaeolaceas, 

 and Lemnanthaceae contain peculiar nitrogenous glucosides 

 which become decomposed into sulphur-bearing substances, 

 long known as mustard oils, by means of the enzyme myrosin. 



Myrosin. — Myrosin is an enzyme occurring in certain spe- 

 cialized cells in the seeds and other parts of many Cruciferae, 

 etc. The cells containing myrosin are stained a deep red by 



