2()4 



SUMMARY OF CURRENT RESEARCHES RELATING TO 



Chemical Reactions of Chlorophyll.* — A. Tsebirch points out in 

 the followiug tabic the differences in tbo reactions of pure cbloropbyll 

 anil of tbo greou anilin-dyes. 



Hydrochloric acid . . 

 Ether 



Spectroscopic cxaminatiou 



Fluorescence 



Chlorophyll. 



Blue. 



Yellow 



(colourless when xantho- 



phyll is absent). 



Dark band in the red 



(3 bauds from yellow to 



green). 



Red, even in very dilute 

 solutions. 



Green Anilin-dyes. 



Yellow. 

 Colourless. 



Inner band in the rod. 



None. 



The chlorophyll-pigment of commerce is a mixture of pure chloro- 

 phyll and xantbophyll. These may be separated by a surface layer of 

 benzin, which removes the chlorophyll. Insolation by direct sun- 

 light may also sometimes be used ; the sunlight removing the colour 

 from chlorophyll-connyl. 



Colouring-matters of Flowers and Fruits.f — A. Hansen asserts 

 that the great variety in the colour of flowers can be referred to a very 

 small number of original pigments. Excluding chlorophyll, the 

 remainder may be divided into three main groups, viz. : — (1) yellow 

 coloui-s ; (2) red colours ; (3) blue and violet colours. Of these the 

 first group resemble chlorophyll-green in being connected with 

 organized protoplasm-structures, while the members of the two 

 other groups are closely connected with one another, and sharply 

 separated from the yellow pigments, occurring always dissolved in 

 the cell-sap. 



The yellow pigment of flowers has the form of an oily compound 

 imbedded in a protoplasmic matrix, whence its insolubility in water. 

 Hansen terms it " lipochrome," from its resemblance to that animal 

 pigment. It crystallizes in needles, insoluble in water, but readily 

 soluble in alcohol, ether, chloroform, petroleum-ether, and bisulphide 

 of carbon. In the solid form it is coloured blue by sulphuric acid, and 

 green by biniodide of potassium. Its spectrum exhibits scarcely any 

 variability ; its solutions do not display fluorescence. An orange tint 

 is produced by a dense accumulation of lipochrome in the chromato- 

 phores. In a few cases, as the flowers of the dahlia and the rind of 

 citrons, the yellow colour is not produced by lipochrome, but by a 

 yellow pigment dissolved in the cell-sap. 



The red colours of flowers may all be referred to a single red 



* Vers. Deutsch. Naturf. u. Aerzte Magdeburg, Sept. 23, 1884. See Bot. 

 Centralbl., xx. (1884) p. 122. 



t Verb. Phys.-med. Gesell. Wiirzburg, xviii. (1884) pp. 109-27 (2 pis.). 



