4 AGRICULTURAL BACTERIOLOGY 



trates, phosphates, and sulphates, and forms from them 

 all of the varied substances found in its tissues the woody 

 fiber, the sugars, the starches, the fats, the gums, the waxes, 

 and the proteins. The green plants are builders of organic 

 matter and storers of energy. They represent the construc- 

 tive or the synthetic group. 



Living forms that do not possess this wonderful energy- 

 receiving and -utilizing compound, chlorophyl, can not use 

 the radiant energy of the sun directly, but must rely upon 

 that which the green plant has stored in its structure. 

 These forms use vegetable matter as food, and obtain 

 therefrom their building materials and the energy neces- 

 sary for all their life processes. They utilize the energy and 

 leave behind simpler types of compounds than those in- 

 gested. They break down vegetable matter, and are to be 

 classed as destructive agents, or as analytic factors. The 

 animal that lives upon the tissues of another animal is still 

 relying upon the green plant for its food and energy. It 

 is to be seen that the basis of classification is, whether the 

 energy needed by the organism is obtained directly from 

 the sun, or indirectly through the medium of another or- 

 ganism. 



Destruction of man-made structures is as necessary as is 

 the building thereof, and so it is in nature. The supply of 

 plant food is limited, and it is essential that the elements 

 in vegetable matter be returned to a form that permits of 

 use by another plant. This is the work of the destructive 

 group. The green plant furnishes to all other forms of 

 life food and energy. They, in their turn, supply the green 

 plant with food. Each group is absolutely dependent on 

 the other for its continued existence. 



Not all the members of the destructive group are animals. 

 In it are placed many forms that every one recognizes as 

 plants. They are devoid of chlorophyl^ and demand the 



