RELATION OF PLANTS TO ENVIRONMENT 



9 



OUTGO 



2. ORGANIC 

 FOODS 



and energy which they furnish for the maintenance and welfare 

 of man in the home and in the industries. 



Food relations of plants and animals. The food relations of 

 plants to man and animals can be most easily understood by com- 

 paring the. income and outgo of a common green plant with that 

 of a man, or of an animal similar to man in its feeding habits. 



For this comparison Figs. 2 and 8 may be used. The cir- 

 cle in each figure may be taken to represent the plant or 

 animal body con- 

 taining the living INCOME 

 substance that both 

 does the feeding and 

 produces the energy 

 for the living or- 

 ganisms. These fig- 

 ures illustrate the 

 fact that the ani- 

 mal bears the same 

 general relation as 

 the plant to lifeless 

 matter, to the pro- 

 duction of energy, 

 and to the elimina- 

 tion of wastes. Life- 

 less matter, in the 



form of foods, bread, butter, and meat, is taken into the 

 body, digested and assimilated by the living substance of the 

 animal body, and converted temporarily into living matter as 

 illustrated in the figure. The living matter thus produced 

 from lifeless foods is then oxidized, and this process yields 

 energy for the ordinary animal activities. The waste materials 

 produced by this oxidation are then cast out of the body in 

 the form of carbon dioxide, water, and nitrogenous wastes ; 

 and there is some loss, of energy with the heat that escapes 

 from the body. 



A real difference between the animal and the plant, however, 

 lies in the nature of the lifeless matter taken in. In the animal 



3. INORGANIC 

 MATERIALS 



a. WATER 



b. OXYGEN 



C. SALTS 



FIG. 3. Diagram illustrating the nutrition of 

 an animal 



The income, outgo, and products of constructive and 



destructive processes are shown as for the green plant 



in Fig. 2. Compare Figs. 2 and 3 and consult the text 



for further discussion 



