THE ENERGY OF THE LIVING PROTOPLASM. 183 
tion products by it, while they remain colourless during their stay 
in normal cells. (I) 
How weak the oxidising power of the cells appears to be here 
and then how energetic when sugar comes under action ! We 
search the entire domain of chemistry in vain for a single case of 
the occurrence of complete combustion when an organic compound 
in aqueous solution absorbs oxygen from the air; (2) even the well 
known energetic absorption of oxygen by alkaline solution of 
pyrogallol does not lead to a complete combustion. Only the 
action of free permanganic acid can exhibit similar results. 
However, there exist cases where partial oxidations by 
molecular oxygen can easily take place. We will mention the 
transformation of aldehydes into acids, of hydrazo-benzene to 
azobenzene, of indigo white into indigo blue. Also the be¬ 
haviour of anthraquinone, oxindol, and amidophenols to common 
oxygen may be cited. The total change here taking place 
consists either in the entrance of one oxygen atom into the 
molecule or in the withdrawal of two hydrogen atoms. Other 
compounds again acquire the property of absorbing free oxygen 
through the presence of an alkali, as pyrogallol, pyrogalloquinone, 
chrysarobin, furoin. (3) Benzene acquires it by the presence of 
aluminium chloride. In all these cases there exists evidently a 
high degree of lability in certain hydrogen atoms leading to the 
absorption of oxygen. This lability is due to their specific posi¬ 
tion in the molecules. (4) We observe under ordinary circum¬ 
stances, however, no labile hydrogen atoms in the fatty acids 
proper, but nevertheless the latter are easily burned up in the 
cells. We must then logically conclude that contact with the. 
living protoplasm suffices to impart a state of lability to the atoms 
in the molecules of the fatty acids, recalling the action of 
(1) Ber. Sachs. Akad. d. Wiss., 1889, p. 493. These observations likewise proved 
the absence of H2O2 in plant-cells. 
(2) It is obvious that the energetic autoxidation of zinc ethyl, dimethyl arsine, 
monobrom-acetylene and of the sodium compounds of ketones and aldehydes, which 
burst into flame in contact with air cannot serve for comparison. 
(3) A preliminary “ activifying ” of oxygen takes place here just as little as in 
the living protoplasm. 
(4) Lability of hydrogen linked to carbon may be of two kinds : one which 
determines its easy exchange by certain metals, as in acetylene, the other which 
causes its increased affinity for oxygen, as in aldehydes. 
