RESPIRATION 93 
By comparing the final results of the anaerobic and aero- 
bie 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. 
