CYCLE OF MATTER AND ENERGY 



121 



the CO2 is given off into the air while oxygen is taken into the 

 plant from the air, but this fundamental process of respira- 

 tion is masked by the more active processes going on under 

 the action of chlorophyll, so that, in sunlight, the oxygen needed 

 is provided by the residue of oxygen after starch is formed, 

 the remainder being given off, while the waste matter CC>2 is 

 reduced and ultimately manufactured into starch. The essen- 

 tials of respiration, therefore, go on all the time, but C02 is actu- 



ERlA . ACETIC ACID 

 * BACTERIA -CO . 



I I 



5ALT5(Ca, Ha, P, Fe.TTi<j, 5. nttj.ffcj CCfe 

 NITRATES . NITWTE5 



. CO NITf?ATE5 



' PHOSPHATES 



OTHER SALTS 



EARTH -"WATER 



PIG. 48. Diagram illustrating the cycle of living matter and energy in animals, 

 plants, yeast and bacteria. 



ally given off by the plant only in the absence of sunlight. The 

 oxygen given off cannot be considered a waste matter or prod- 

 uct, since it has not been a part of the plant organism but 

 is only a by-product of chlorophyll activity. Nitrogenous 

 waste may be disposed of, when present in small quantities, by 

 being stored in the leaves, and finally cast off by the annual 

 shedding of leaves and their contents. 



Cycle of Matter and Energy. The autotrophic nutrition of the 

 fern, and of plants generally, is the starting point for the wonder- 



