45 
that would destroy with great vigor and promptness a product neces- 
sary for its respiration. 
Thé protoplasm represents a most complicated machine, built up 
of easily changeable proteids. This éasy change to comparatively 
stable forms, in the process of dying, implies a loss of the labil atomic 
groups by atomic migration in the molecules, and a loss of kinetic 
chemical energy.’ The atoms of the labil groups are in continuous 
motion, representing a charge with kinetic chemical energy. This 
energy is transferred by the protoplasm to the thermogens, princi- 
pally sugar and fat (lecithin), which at the ordinary temperature are 
not at all disposed to oxidize themselves directly on contact with air. 
By contact with the living protoplasm, however, they become capable 
of thus oxidizing themselves, since the protoplasm imparts to their 
atoms such a state of motion that their affinities are loosened and they 
can take up oxygen from the air without the oxygen being previously 
activified. This splitting of the oxygen molecules and the combining 
of the oxygen atoms with the atoms in sugar and fat proceeds at one 
and the same moment; but at the same time certain labilized activified 
hydrogen atoms of the thermogens can combine with still entire mole- 
cules of oxygen, thus forming hydrogen peroxid as a by- product, as 
previously mentioned. . 
The heat produced by the combustion of the thermogens is again 
turned in a certain measure by the living protoplasm into chemical 
energy, since the heat energy instigates the atoms of the labil groups 
to much more intense oscillations than is the case with the more stable 
atoms. The easy transformation of heat energy into chemical energy 
is known. The former represents motions of molecules and atoms, 
the latter an atomic motion which consists of oscillations of a greater—— 
amplitude than the motions induced by heat energy. This can be 
inferred from the fact that, other things being equal, chemical energy 
is capable of loosening affinities in molecules much more readily than 
heat energy can at a moderate temperature. 
When the thermogens are consumed in the cell without a fresh sup- 
ply being available, the labil proteids of the living protoplasm them- 
selves take up oxygen. Thus by their partial oxidation a disturbance 
is produced which may, at a certain stage, lead to the total collapse of 
the protoplasm with a loss of all the labil groups. This is the death 
of the cells by starvation. . 
When, however, thermogens are present but the oxygen is with- 
held, the activified molecules of sugar undergo other changes, brought 
on by the far-reaching loosening of affinities, and lactic acid, aleo- 
hol, or fat result, accompanied by a simultaneous production of 
1 This energy is perceptible as heat in the dying of the ene tissues of aia 
the so-called postmortem rise of temperature. 
