THE ENERGY OF THE LIVING PROTOPLASM. 187 



accompanied by a development of carbon dioxide, and have 

 received the name : intramolecular respiration. (I) 



If the amount of respiratory fuel decreases, the intensity of 

 respiration will diminish also, and finally, the active proteids of 

 the living protoplasm will, on account of their lability, themselves 

 take up oxygen. And if in a cell a small amount of protoplasm 

 has thus been changed, the equilibrium of the entire tectonic will 

 be disturbed and a rapid chemical change will follow the contrac- 

 tion : death by starvation. The protoplasm, however, as if endow- 

 ed with intelligence, understands how to avoid this dangerous 

 result. It absorbs food and instead of itself taking up oxygen, 

 throws it upon the " activified " molecules of food and thus 

 derives the greatest profit to itself, the liberated energy being 

 utilisd for various vital functions. A great part assumes the 

 form of heat and is dissipated, another part that of mechanical 

 activity, another, again, serves to increase the original plasmic 

 energy and leads thus to the most wonderful chemical perform- 

 ances. 



But the increased state of lability will lead in turn to an 

 increased respiration, and this, again, to an increased lability. 

 Thus the temperature would continuously rise also, and another 

 dangerous point would be reached : death by heat, at 45-50°C. 

 The increased motions of the labile atoms would facilitate the 

 reaggregation into stable position, the passage into passive 

 proteids by the action of the labile groups upon each other; 

 we may define this death as caused by an intramolecular self- 

 poisoning. However, there exist, again, conditions to prevent 

 this result, heat being lost by conduction, by radiation, and, 

 further, by evaporation of water. Higher animals also enjoy the 

 benefit of regulating contrivances in the nervous system. It is, 

 nevertheless, admirable to see how close the temperature of 

 birds is kept to that dangerous degree which, like an abyss, 

 separates life from death. And still more remarkable are the 



(1) The view of several authors that the so-called intramolecular respiration is 

 the primary cause of normal respiration has been refuted as erroneous by Sachs, 

 Diakonow, Godlcwski, and others. In most organisms absence of oxygen acts 

 detrimentally, but in cold blooded animals and plants much more slowly than in 

 warm-blooded animals, while anaerobic microbes and yeasts can do without it 

 altogether. 



