566 ELEMENTS OF PLANT HISTOLOGY AND MICROTECHNIC 



Chlorophyll. Chlorophyll may be extracted from the chloroplasts by means 

 of strong alcohol. When this extract is shaken up with benzol and a few drops of 

 water, and allowed to stand for a short time, the benzol which rises to the top will 

 contain two pigments, amorp hous chlorophyll-green and carotin; while the lower 

 stratum of alcohol will contain a crystallizable chlorophyll-green and xanthophyll. 

 The amorphous and the crystallizable chlorophyll-green differ in the character of 

 their spectra and in t heir solubility in different reagents. The amorphous form is 

 soluble in alcohol, petroleum ether, carbon bisulphide, and benzine; while the 

 crystallizable is soluble only in the alcohol. 



Colchicine, C22H i8 NO6. This occurs in a few rows of cells immediately sur- 

 rounding the vascular bundles of the corm of Colchicum autumnale. Treated with 

 a mixture of I part of sulphuric acid and 3 parts of water colchicine is colored 

 yellow, and this color is changed to a brownish-violet by the addition of a crystal 

 of potassium nitrate. Iodine stains it brown, and potassic-mercuric iodide and 

 hydrochloric acid produce with it a yellow precipitate. 



Corydalin, CigHigNO*. This is an alkaloid which is found in the idioblasts of 

 the Fumariaceae. When corydalin is present, ammonia produces a dark gray color, 

 picric acid a yellow, and potassium iodide-iodine a deep reddish-brown color. 



Crocin (Saffron -yellow), C44H7oOo 8 . This is a glucoside occurring in the stigmas 

 of Crocus sativus. When concentrated sulphuric acid is added to crocin, a deep 

 blue color is produced which passes into violet, cherry-red, and then brown. Nitric 

 acid also produces a blue color which passes into brown. 



Curarin. This occurs in the parenchyma and bast of several species of 

 Strychnos. Concentrated nitric acid produces with it a blood-red, and dilute or 

 concentrated sulphuric acid a carmine-red, color. 



Curcumin, CuH.uO*. Curcumin occurs, dissolved in an ethereal oil, in certain 

 cells of the ground parenchyma of the rhizome of Curcuma longa. -It crystallizes 

 in the form of yellow needles which have a bluish tint by reflected light. Lead 

 acetate forms a brick-red precipitate with curcumin, and sulphuric acid gives it a 

 crimson color. 



Cutin. Cutin is a substance which is nearly related to suberin (which see), but 

 is not identical with it. None of the acids derived from cutin is identical with any 

 derived from suberin. However, the micro-chemical reactions of suberin and cutin 

 are the same. They are insoluble in concentrated sulphuric acid and cuprammonia 

 and are colored from yellow to brown with the iodine reagents. When heated with 

 concentrated potassium hydrate, they form yellowish droplets and granular masses. 

 When heated in nitric acid and potassium hydrate, they form droplets which melt 

 tetween 30 and 40 C., and which are soluble in boiling alcohol, ether, benzol, 

 chloroform, and dilute potassium hydrate. Both suberized and cutinized walls 

 resist concentrated chromic acid at ordinary temperatures. Chemical analysis 

 shows that cutin is composed of compound esters and fatty acids, and when heated 

 to 300 in glycerine, it behaves as a fatty body. For staining cutinized walls, see 

 under Cyanin, Alcannin, Chlorophyll Solution, Double Staining. 



Cytisin, C 2 oH 2 7N 3 O. This alkaloid occurs in the seeds of Cytisus laburnum 

 and of other species of Cytisus. It occurs in less abundance in other parts of the 

 plant, such as the petals and peripheral tissues of the stem. Potassium iodide- 

 iodine produces with it a reddish-brown, granular precipitate which is soluble in 

 sodium hyposulphite. Chloride of iron gives an orange-red color with cytisin. 

 With phosphomolybdic acid a light yellow precipitate is produced, and picric acid 

 when added to thin sections containing cytisin produces crystal groups of a reddish- 

 yellow color. 



Datiscin, C2iH 2 2Oi 2 . This glucoside is found in the cell-walls of the wood and 

 bark of Datisca cannabina. Lime and baryta waters produce with it a yellow 



