Heat generated by the dark-adapted squid retina in response to light pulses

A rapid increase in the temperature of the dark-adapted squid retina evoked by a brief light pulse was detected with a pyroelectric detector. The amount of heat generated by the retina in response to a pulse of blue light of moderate intensity was far greater than that produced by direct conversion of the stimulating light by the retinal pigments into thermal energy. D-Glucose in the medium was required to maintain the ability of the retina to produce light-evoked thermal responses.