112 THE VEGETATIVE FUNCTIONS OF PLANTS 
TABLE III. COMPARISON OF PLANT AND ANIMAL RESPIRATION 
Plant respiration Animal respiration 
1. Oxidations occur within the tissue i. Ditto 
2. Oxygen taken in 2. Ditto 
3. Carbon dioxide given off 3. Ditto 
4. Heat evolved '. 4. Ditto 
5. Water-vapor formed 5. Ditto 
6. Dry weight decreased 6. Ditto 
7. Potential energy becomes kinetic 7. Ditto 
8. Occurs in every living cell 8. Ditto 
9. Occurs without ceasing, day and night 9. Ditto 
10. Accomplished by respiratory enzymes 10. Ditto 
114. Respiration and Fermentation. Perhaps one of 
the most surprising and interesting of all the results of the 
study of respiration is the revelation of the fact that 
the real process of respiration (the oxidation of living tis- 
sues, as distinguished from the exchange of gases by 
breathing, or otherwise) is accomplished by enzymes 
known as oxidases, and is therefore, in reality, a form of 
fermentation. In fact, the more deeply we study all the 
fundamental processes of living things, the more it 
seems to become evident that every chemical process in 
organisms, in fact, that life itself is absolutely dependent 
upon fermentations. We are brought face to face with the 
almost startling fact that such commonplace phenomena as 
the ripening of fruit, the raising of dough, and the decay 
of plant tissues, are conditioned by the same class of sub- 
stances (enzymes), and by the same kind of processes that 
underlie the digestion of food, the respiration of tissues, 
and the thinking of human minds. And, moreover, we 
seem to be led to the odd conclusion that living organisms 
do not respire because they take in oxygen, but that they 
take in oxygen because they have respired. 
