Note
Unlike incandescence, where the electronically excited state is a consequence of thermal excitation of electrons, chemiluminescence is essentially heatless. Although bioluminescence is often referred to as phosphorescence, as in the quote from Darwin in the next section, this is a misnomer. In phosphorescence the electronically excited state is generated by light absorption, rather than a chemical reaction, and light emission persists for a limited period of time after removal of the excitation source.