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, Godlewski, 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 anaérobie microbes and yeasts can do without it 
altogether. 
