CELL-CONTENTS AND FORMS OF CELLS. 177 



petals of certain lilies, where we find some cells of a deep purple 

 color, others of a deep red, and still others of intermediate shades. 

 These substances are easily extracted with water or dilute alco- 

 hol and are all more or less affected by certain chemicals (many 

 of which occur naturally in the plant), such as citric acid, oxalic 

 acid, salts of calcium, iron, aluminum, etc. 



FIG. 104. Microcrystals formed in Kava-kava, the root of Piper methysticum: 

 A, crystals of methysticin obtained on treatment of sections of the root or the 

 powder with alcohol, the crystals being long rods, of p. light yellow color, attaining a 

 length of 0.160 mm. and becoming violet red on the addition of sulphuric acid. B, 

 Crystals of methysticinic acid obtained upon heating a small quantity of the powder 

 with one or two drops of a solution of potassium hydroxide, then adding dilute 

 alcohol and allowing the slide to stand for 24 hours. Crystals of methysticin can 

 also be obtained upon sublimation, providing the powder has been acted on previously 

 with dilute sulphuric acid, emulsin, or saliva. After Tunmann in Gehe & Co.'s 

 Handelsbericht, 1912. 



A number of plant pigments of this class are used as indi- 

 cators in volumetric chemical analysis, their use in this connection 

 being dependent upon their sensitiveness to acids and alkalies. 

 The fact that they respond to iron salts, that is, give a blue or 

 green reaction with these salts, would indicate that they are 

 associated with tannin or that they are tannin-like compounds, as 

 has been supposed by some writers, but they behave very differ- 

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