930 The Variability of Protoplasm. { September, 
chemical compounds are decomposed, and that a complex chem- 
ical compound results, rendered highly unstable through the 
withdrawal of oxygen. The chemical stagnation to which oxida- 
tion has reduced the elementary constituents of the earth is 
partly overcome by this process of deoxidation, and active oxida- 
tion becomes again possible. 
This active oxidation displays itself in the animal body. The 
elements concerned fall back towards the state of chemical sta- 
bility from which they were removed, and the energy emitted 
during this descent is that which constitutes animal life. But if 
deoxidation is the chief chemical principle involved in the forma- 
tion of protoplasm, why is it confined to the elements mentioned? 
A probable answer seems to be that these elements alone exist 
upon the earth under conditions which render such deoxidation 
possible. The other abundant oxides are solids, and therefore 
removed from any active influence of the agencies which aid the 
deoxidation of carbon. Some of these elements exist, either in 
their elementary or in a compound form, dissolved in water, and 
perhaps in consequence are found in protoplasm. Under proper 
conditions they might become active instead of passive agents m 
protoplasm. Some of them which are generally diffused, such as 
sulphur and phosphorus, seem to be essential constituents of 
protoplasm. 
This review leads us to a significant conclusion. Protoplasm 
is a result of the successive deoxidation of the only elements 
whose physical condition renders them susceptible to this chant 
There is nothing to prove that such a process is necessarily con 
fined to these elements, or that, if a state of affairs should ppa 
in which these oxides existed as solids, and some other oxides 
took their place as liquids and gases, an organic molecule me 
ing to protoplasm could not be produced by a like deoxidation A 
these latter elements. To affirm that carbon is the only elene 
which can be deoxidized by the aid of sunlight, or by any ware 
free energy, is to affirm something of which we can os 
knowledge, and it is possible, and even probable, that m gs 
spheres whose atmospheric constituents may consist of Bee ` 
chemical compounds analogous to, but not identical with, p 
of our atmosphere, a like process of decompounding and rec 
: i be active, 
pounding into complex and unstable molecules may ie 
and organic forms exist. To this effect of course the pre So 
