CHAPTER VII 



RESPIRATION 



LIFE means change. We cannot imagine its continuance with- 

 out liberation of energy. Arrest of molecular activity is death. 

 There is no possibility of its revival. A watch that has stopped 

 may be started by shaking. On the cessation of molecular 

 activity an animate being becomes inanimate. Dead, it is 

 liable to further chemical changes. Bacteria invade it. They 

 shake down its complex unstable compounds into simple, stable, 

 so-called "inorganic groups"; but the ordered combination with 

 oxygen, which constitutes living, can never recommence. Putre- 

 faction may be prevented by the exclusion of germs. The 

 inanimate mass of organic material may remain unchanged. 

 Its return to life would be a miracle. From time to time a 

 frog is found enclosed in old red sandstone, or some other rock 

 which for countless ages has lain beneath the surface. The 

 cleft through which the frog entered a few hours or days before 

 it was discovered is overlooked. It is supposed to have lived 

 " in a state of suspended animation " for millions of years. 

 The fact that no frogs are to be found among the fossils of the 

 old red sandstone is an objection too casuistical to be seriously 

 entertained. The physiologist's demand to know what has 

 become of the mountains of solid carbonic acid, water, and 

 urea which the frog must have produced during its unimaginable 

 term of incarceration is regarded as the natural expression of 

 his prejudice that life cannot continue without molecular 

 change. And he is bound to admit his inability to prove that 

 it cannot. Nevertheless, his experience that, whenever and 

 however he may, by experimental methods, arrest change, he 

 loses the power of causing it to recommence justifies him in 

 his conviction that life is change. Even a living seed is to his 

 mind an organism whose complex constituents are slowly 



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