26 PLANT DISEASE 



carbon dioxide, and this only under the in- 

 fluence of light." 



2. " The feeding of plants upon carbonic 

 acid is invariably accompanied by the pres- 

 ence of a peculiar green colouring matter. 

 Chlorophyll, the protoplasm of the plant, is 

 enabled to seize the carbon of the mineral 

 world. There are plants which have no 

 chlorophyll, and are thus unable to feed upon 

 carbonic acid." 



Further, in Text-Book of Botany Morpho- 

 logical and Physiological, by Julius Sachs, 

 Professor of Botany in the University of 

 Wurzburg, edited by Sydney H. Vines. D.Sc., 

 F.L.S., we read 



3. "It is only the cells which contain 

 chlorophyll, and only those under the influence 

 of sunlight that have the power of decompos- 

 ing the carbonic dioxide taken up by them. 

 The compound of carbon originally present in 

 the earth is the dioxide, and the only abun- 

 dantly active cause of its decomposition and 

 of the combination of carbon with the ele- 

 ments of water is the cell containing chloro- 

 phyll. Hence all compounds of carbon of 

 this kind, whether found in plants or in 



