410 Transactions of the Boyal Society of South Africa. 
again into sugar need not be considered.) Some of the energy thus 
hberated is available for metabolism, i.e., to bring about further de- 
compositions of substances in the cell or of the protoplasm itself. During 
the reconstruction of compounds in the cell some energy would again be 
given out, so that the final result of the whole metabolism of any living 
cell is a liberation of heat or energy. A substance like sugar therefore 
does not contain a store of energy, but energy is required to break it up 
before it can be used in the anabolic processes of the cell. 
In colourless cells the metabolism also involves the using up and 
liberation of energy. As shown above, it cannot be stated that protoplasm 
is endowed with a supply of energy, and yet before any decomposition 
commences, say in germinating seeds, some energy must be available. 
The prevailing idea is tha^t the protoplasm, as it were, wakes up and 
immediately goes to some store of energy in the cell, but as already 
pointed out, there can be no store of energy in a cell. There can be no 
energy available until some chemical union has taken place, i.e., energy 
is usually liberated in the building up of compounds from elements and 
simpler compounds, especially in the case of plant compounds. It is 
probable that in this connection water, without which germination is 
impossible, plays a more important part than is usually attributed to it. 
The presence of water in germinating seeds may cause some chemical 
combination between the water and some substance in the cell or the 
protoplasm itself. The energy thus liberated would probably be sufficient 
to start the decomposition of other substances in the cell, say starch, and 
thus the metabolic processes would commence and so continue. The 
energy required in the decomposition of starch may be represented in the 
chemical equation thus : — 
CgH.oOs - 6C0, + 6H,0 + 365,000 cal. 
Ferments, enzymes, &c., need not be here considered as factors in the 
metabolism of the cell, as their actions are more or less bound up with 
the vitality of the protoplasm. In any case they have first to be manu- 
factured by the protoplasm. Now oxygen as well as water is necessary to 
start the metabolism of the cell, and it may be that oxygen does the same 
thing as suggested above for water, that is, by entering into some chemical 
union with the protoplasm set free the first available energy. If that 
were so it is not apparent why the continued presence of oxygen should 
be necessary, or for that matter water, but water is probably used 
mechanically in growth as well as for the constructive processes of the pro- 
toplasm. It has been demonstrated in the case of the frog that it is not 
only able to live for some time in an atmosphere devoid of oxygen, but 
that it will even continue to exhale carbon-dioxide. Similar demonstra- 
tions can be made in the case of plants. Under such circumstances it is 
