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SORBY S RESEARCHES ON CHROMATOLOGY. 



For comparison I give the following : — 



I. Fucus serratns grown in the shade. 



II. The same plant grown in the sun. 



III. Oscillatoria grown under water, in a cold spring, in a very 

 shady place. 



IV. The same plant, in the same spring, where more exposed to 

 light. 



V. The same plant, growing in and on the surface of water, 

 where fully exposed to direct sun. 



VI. Probably a different species of Oscillatoria, growing on a 

 damp wall, completely exposed to the sun. 



VII. Peltigera canina, slightly shaded, and having much fructi- 

 fication. 



VIII. The same plant, where much exposed to the sun. 



In this Table are compared together the same or very similar 

 plants growing in different conditions, as connected by the brackets, 

 and also plants belonging even to different classes. On comparing 

 together the amount of the different constituents of the same plants 

 grown in less or more light, it will be seen that some of the differ- 

 ances are in perfect agreement with those already described ; but 

 the differences in the Oscillatoria? are evidently not a mere change 

 in equilibrium, due to the decomposing action of the light, and 

 point unmistakably to a great difference in the constructive force 

 of the plant, depending on increased light. There is a remarkable 

 development of phycoxan thine and orange xanthophyll, and a great 

 decrease in the amount of chlorofucine and fucoxanthine, and the 

 result is that we have a change almost from the type of olive Alga? 

 to that of certain lichens. When growing in a very shady place 

 the colouring-matters soluble in bisulphide of carbon are all iden- 



