CYCLE OF MATTER AND ENERGY 



121 



the CO-2 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 CO 2 is 

 reduced and ultimately manufactured into starch. The essen- 

 tials of respiration, therefore, go on all the time, but 62 is actu- 



DEAD ANIMAL5 

 PLANTS 



+ YEAST = ALCOHOL 



! 



t BACTERIA . ACETIC ACID 

 I 



NITROGENOUS WASTE 



1- BACTERIA - CC; . h,0 



t BACTERIA = NH, C0 2 



5ALT5(Ca. Ha, P. Fe.Tn^, 5, 

 NITRATES , NITRITES 



Nn, 



CO, 



NITRATES 

 FI105PHATES 

 OTHER SALTS 



EAR Th"~ WATER 



FIG. 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- 



