CHLOROPHYLL-CORPUSCLES AND AMYLOID DEPOSITS. 231 



green-coloured substance which tints the " chlorophyll 

 bodies " of higher plants. 



The introduction of the spectroscope^ as a means of iden- 

 tifvinfT coloured substances in solution, has resulted in the 

 discovery of the complex nature of " chlorophyll." Start- 

 ing from the important observations of Stokes, followed by 

 those of Kraus and other continental observers, we come to 

 the latest and most complete investigation of " chlorophyll," 

 which is that of Mr. Sorby. 



Sorby had the advantage of having made an extensive 

 study of vegetable and other colouring matters by the aid of 

 his beautiful micro-spectroscope and the systematic use of 

 chemical reagents. His method of investigation is primarily 

 based upon that of Stokes. He distinguishes, in relation to 

 the green leaves of the higher plants, colouring matters 

 soluble in water (erythrophyll and clirysotannin group) 

 and those soluble in absolute alcohol and often in carbon 

 bisulphide (chlorophyll group, xanthophyll group, and 

 lichnoxanthine group). The green substances are those 

 known as the " chlorophyll group/' and occur in the so- 

 called chlorophyll bodies in association with the yellow 

 substances of the xanthophyll and lichnoxanthine groups. 

 The chlorophylls are distinguished as blue and yellow 

 chlorophyll, found in higher plants, and chlorofucine, which 

 occurs in association with the two preceding, in certain Algae. 

 Blue chlorophyll is separated from yellow chlorophyll by its 

 greater solubility in certain media. The absorption spectra 

 of these and of chlorofucine present bands differing in posi- 

 tion; they are in each case precisely fixed and represented 

 in a diagram by Sorby, as are the absorption bands of each 

 species of the xanthophyll and lichnoxanthine groups. 

 Upon all these substances acids and alkalies have certain 

 definite effects, in some of them profoundly modifying the 

 absorption spectrum, and clearly giving rise to new chemi- 

 cal compounds; whilst in other cases a slight modification 

 only is produced by such reagents. According to Sorby, 

 various observers previous to himself had, in studying the 

 absorption spectrum of the alcoholic extract of a green leaf, 

 considered the seven-banded spectrum due to a mixture of 

 blue and yellow chlorophyll, together with the products of 

 the action of acids upon those substances — as characterising 

 one simple substance — the so-called " chlorophyll.''^ Accord- 

 ing to Sorby, such a mixture occurs ordinarily in alcohol 

 when allowed to act upon a green leaf. Various analytical 

 processes must be used to separate the various bodies thus 

 occurring in company, and precautions adopted to prevent 



