RESPIRATION 93 



By comparing the final results of the anaerobic and aero- 

 bic respiration of glucose with the steps in the photo- 

 synthetic production of glucose we realize that the proc- 

 esses are the reverse of one another. It is reasonable 

 to suppose then that the amount of energy set free in 

 the processes of respiration will equal that required to 

 build up the same amount of glucose in photosynthesis. 

 Viewed from this standpoint respiration is the process 

 by which the plant obtains at the places where it is needed 

 the energy taken in from the light by the chloroplasts. 

 The manufacture by photosynthesis of an excess of 

 carbohydrates over that used each day by the plant in 

 respiration enables the plant to store up a large amount 

 of energy for the winter season when photosynthesis 

 cannot occur or for the rapid growth of new organs 

 another season. With all the processes of respiration 

 the protoplasm, the living part of the cell, is intimately 

 connected. It is to it that the energy set free is probably 

 transferred. It is apparently the protoplasm that regu- 

 lates the amount and location of the respiratory activi- 

 ties. How all this is brought about is still unknown as 

 is the relation of the structure of protoplasm and the 

 energy used to what we call "life." 



141. In place of the type of respiration described 

 above a few bacteria obtain their energy in other ways. 

 Thus the nitrite bacteria oxidize the ammonia of am- 

 monium salts to nitrites and the nitrate bacteria oxidize 

 the nitrites to nitrates, each of these processes setting 

 free a small amount of energy which is made use of by 

 the bacteria. In both cases the energy thus obtained is 

 sufficient to enable the cells to build up from carbon 

 dioxide and water the carbohydrates needed in the 

 cell's growth and further to combine these with the nec- 

 essary substances to form proteins and protoplasm. 



