Respiration, Aeration, and Fermentation 281 



animals the " heat of respiration " and the " energy of 

 respiration " became well-known terms, so that respira- 

 tion acquired a significance far wider than at first. In 

 spite of this, the mechanism effecting gas exchange and 

 the production of certain of the more common products 

 of respiration (CO and water) long received consideration 

 as respiration. In more recent times the determination 

 that the fundamental changes involved are those taking 

 place in the living cells themselves has therefore stretched 

 further the use of this term. In both animals and 

 plants these changes alike in kind are the essential 

 features of respiration. 



At present there is a clear distinction between the 

 usual oxygenating or aerating processes * and the en- 

 ergy-releasing changes occurring in the cell. These last 

 have been termed " energesis," a term differing from 

 catabolism chiefly in its more limited application and in 

 laying emphasis upon the current view of the chief effect 

 of respiration. 



161. An obvious result of respiration. If an animal is 

 given no food-materials, even for a single day, it must lose 

 weight, although it may be supplied with the normal 

 amount of water. A green plant placed in distilled water, 

 and deprived of light the essential condition for the 

 making of organic food will lose from day to day in 

 dry-weight of its substance. Similarly, seeds germinated 

 in darkness may, with requisite water, increase many times 

 in bulk; but the dry- weight will constantly decrease, so 

 rapidly, in fact, that quickly germinating seeds may lose 



1 The suggestion that these alone should be called respiration seems 

 inadvisable. 



