244 AGRICULTURAL CHEMISTRY 



all of the organic compounds of the plant. Protoplasm 

 is the living part of both plant and animal cells. 



345. Production of Chlorophyl. When the plant cell 

 is first formed, the protoplasm contains no green grains. 

 Small, colorless grains first appear, and then the green- 

 ing of these grains takes place. The chlorophyl body 

 may make its appearance in the absence of light, but the 

 last stage of its development can take place only under 

 the influence of light and at a higher temperature than 

 is required for the first stage of the process. With a cool 

 temperature, there is plant growth, but the vegetation 

 looks yellow because there is not sufficient heat for the 

 completion of the second part of the process of chlorophyl 

 development. Chlorophyl is destroyed by intense light 

 as well as by the absence of light. It is soluble in 

 ether and alcohol and is one of the constituents of 

 ether extract. The green color is easily destroyed, 

 but the chlorophyl body is quite stable and resists the 

 action of dilute acids and alkalies. Chlorophyl loses its 

 activity, and undergoes a decided change in composition 

 as the plant matures. Some of the elements which com- 

 pose the chlorophyl, as nitrogen and phosphorus, are 

 used for seed formation. At the time of the greatest 

 amount of color in plants, there is the greatest cell 

 activity and the largest amount of plant tissue is being 

 produced. When a plant ripens, the decline of activity 

 of the cells can be observed by the change in the color of 

 the plant. When corn, for example, ripens, the lower 

 joints of the stalk turn yellow first, indicating that 

 growth and activity have ceased in those parts. Then 



