Darwinism designates a distinctive form of evolutionary explanation for the history and diversity of life on earth. Its original formulation is provided in the first edition of On the Origin of Species in 1859.
The enthalpy - or internal energy - of a substance is a function of its temperature and pressure. The change in internal energy with respect to change in temperature at fixed pressure is the Specific Heat at constant pressure - cp.
In the diagram on the right, the energy is taken from the surroundings and stored as potential energy in the products. (a) is the activation energy for the reaction to take place whilst (c) is the energy change (known as enthalpy change).