COMPOSITION OF PLANTS AND FEEDS 



plant. In order to eliminate the effect of this variation, the per- 

 centages of other constituents of the plant should be calculated 

 to percentages of the water-free substance, or dry matter of the 

 plant. The statements below refer to the composition of the dry 

 matter. 



The percentage of ash usually decreases with the age of the 

 plant. That is, the production of organic matter takes place 

 more rapidly than the withdrawal of ash material from the soil. 



The percentage of protein decreases decidedly. In some cases 

 the percentages when the seed are nearly ripe are only about half 

 those at the beginning of growth. The protein, however, consists 

 largely of amides or amido compounds in the early stages of the 

 plant's life, and these amides have little or no value for the pro- 



COMPOSITION OF SOME PLANTS AT DIFFERENT STAGES OF GROWTH. 



