AGRICULTURAL BOTANY 



the intercellular spaces and then into the cells. In 

 these cells it comes into contact with the chlorophyll 

 bodies. Under the influence of sunlight the chloro- 

 phyll can decompose the carbon dioxide into its ele- 

 ments, carbon and 

 oxygen, and water 

 (H 2 0) into its ele- 

 ments, hydrogen 

 and oxygen, and re- 

 combine these ele- 

 ments into new 

 compounds, starch 

 and two allied sub- 

 stances, sugar and 

 oil. The starch 

 formed is changed 

 into sugar and then 

 combines with the 

 mineral nitrates, 

 sulphates, and phos- 

 phates taken in 

 through the roots, and forms a complex compound in 

 a manner little understood. This is food for the pro- 

 toplasm of the cells. When supplied with it in proper 

 amounts, the cells multiply in all parts, or, in other 

 words, the plant grows. These starchlike substances 

 may be found in any part of the plant which has chloro- 

 phyll bodies, that is to say, in any part that is green, 

 but the leaves are their greatest producers. It must be 

 remembered that it is only in the presence of light 

 that the chlorophyll bodies can perform this work of 

 decomposition and recombination which results in plant 

 food and consequent plant growth. 



FIG. 67. Diagram of the Formation of Starch. 



