CHEMISTRY OF PLANT GROWTH 243 



cells of the leaves. The mineral food and nitrogen taken 

 from the soil and the carbon dioxid from the air are 

 chemically united in the cells of the leaves to form the 

 various non- nitrogenous and nitrogenous compounds of 

 plants. Chlorophyl and protoplasm are the two substances 

 which take the most active part in the production of the 

 organic matter. 



343. Chlorophyl is the name applied to the material 

 which imparts the green color to plants. It is not a 

 simple compound, but is composed of a number of closely 

 related organic compounds. The chlorophyl body con- 

 tains both organic and mineral matter. Chlorophyllan is 

 one of the compounds obtained from chlorophyl. Iron, 

 phosphorus and magnesium are among the more im- 

 portant mineral elements necessary for the functional 

 activity of the chlorophyl body. This mineral matter is 

 combined with the organic compounds which form a part 

 of the chlorophyl grain. Chlorophyl is contained in the 

 active living cells of plants, but makes up only a small 

 part of the contents of the cell. 



344. Protoplasm. The chlorophyl body is suspended 

 in a gelatinous, colorless liquid called protoplasm which is 

 composed mostly of proteid and albuminoid materials. 

 It is the living substance of the plant organism, and is 

 the part which gives life and activity. In chemical com- 

 position, it is exceedingly complex, and is composed of a 

 number of proteids, albuminoids and other organic com- 

 pounds. The protoplasm, aided by the chlorophyl, has 

 the power of combining the food elements and producing 



