MORPHOLOGY 



"57 



be developed from a similar original substance ; they are all included 

 in the one terra, chromatophores. 



In parts of plants which are exposed to the light the chromato- 

 phores usually develop into chlorophyll bodies or chloroplasts. These 

 are generally green granules of a somewhat flattened ellipsoidal shape 

 (Fig. 55), and are scattered, in great numbers, in the parietal cytoplasm 

 of the cells. All the chloroplasts in the Cormophytes and, for the most 

 part also, in the green Thallophytes present this same granular form. 

 In the lower Algae, however, the chlorophyll bodies may assume a 

 band-like (Fig. 235), stellate or tabular shape. The fundamental 

 substance of the chlorophyll bodies is itself colourless, but contains 

 numerous coloured drops, which are termed GRAN A. These consist 

 of an oleaginous substance, which holds various pigments in solution ; 

 a green, known as chlorophyll or chlorophyll-green ; a yellow, called 

 xanthophyll ; and a reddish orange, termed carotin. These colouring 

 substances may be extracted by means of alcohol, leaving only the 

 colourless plasmic substance of the chlorophyll body remaining. 



The easiest way in which a solution of chlorophyll can be prepared, is to extract 

 the chlorophyll by means of alcohol from green leaves that have been previously 

 boiled in water. The green chlorophyll pigment is also soluble in ether, fatty 

 and ethereal oils, paraffine, petroleum, and carbon disulphide. The alcoholic 

 solutions appear green in transmitted light ; blood red in reflected light, on 

 account of fluorescence. 



If a ray of sunlight be made to pass through a tolerably thick layer of an 

 alcoholic solution of chlorophyll, and then decomposed by a prism, the resulting 



Fig. 56. — Spectrum of an alcoholic solution of chlorophyll extracted from foliage leaves. (After 

 Kbaus.) The absorption bands in the less refractive part of the spectrum (B-E) are given by a 

 concentrated solution, those in the more highly refractive part of the spectrum by a dilute 

 solution. 



spectrum will show seven absorption bands (Fig. 56). The darkest band extends 

 from Fratjnhofek's line, B, to some distance beyond the line 0. The other bands 

 are not so intense : one lies between and D, another near D, and one near E, 

 while the other three bands are broader and cover almost the whole blue half of 

 the spectrum. 



If benzole be added to an alcoholic solution of chlorophyll, prepared as directed 

 above, and the mixture, after being well shaken, is allowed to settle, the benzole 

 will be found to have taken up the chlorophyll pigment and the carotin, while the 

 xanthophyll will be left in the alcohol, and will collect, as a yellow solution, in a 

 layer below the green benzole. The amount of chlorophyll in a green plant is 



