KESPIKATION 301 



molecule of protoplasm apparently does not enter, can 

 only go on in the living cell. Other similar instances could 

 be quoted. 



The probable course of events in respiration is that the 

 oxygen in some way unites with the protoplasm, rendering 

 it unstable, and initiating a series of decompositions which 

 result in the successive formation of many bodies of less 

 complex composition, each successive decomposition pro- 

 ducing simpler ones, till finally carbon dioxide and water are 

 formed. Simultaneously, reconstruction of the protoplasm 

 goes on, many of these residues, instead of being at once 

 decomposed, being in whole or in great part, together with 

 new material supplied to it in the shape of food, built up 

 again into its substance, and again broken down in further 

 decompositions. If the temperature is low, the breaking 

 down of the protoplasm proceeds but slowly, and recon- 

 struction is rapid, so that under these conditions the quantity 

 of oxygen absorbed or fixed as intramolecular oxygen by 

 the protoplasm is greater than the quantity of carbon dioxide 

 formed by its decomposition. At a higher temperature 

 decomposition is much more easily carried on, and its 

 products are more numerous and simpler. The decom- 

 position and recomposition go on side by side, simpler bodies 

 being gradually produced, either by their splitting from the 

 protoplasm directly, or by their being formed at the expense 

 of the more complex decomposition-products during processes 

 of slow oxidation in the substance of the protoplasm, till 

 finally a certain production of carbon dioxide and water is 

 arrived at. So long as the protoplasm remains alive the 

 amount of these is relatively small, reconstruction con- 

 tinually taking place. When, however, the protoplasm 

 dies, simple bodies, such as carbon dioxide, water, and 

 possibly ammonia, in addition, are produced abundantly 

 from the decomposition which attends its death. 



If the auto-decomposition of protoplasm during life 

 involved such a splitting-up as would lead to the formation 

 of nothing but these, nearly all the potential energy of the 



