1. Blue-green algae, red algae, and purple bacteria all show the emission of delayed light.
2. The action spectra for the production of delayed light by three species of blue-green algae have one broad band with a peak at 620 mµ.
3. The action spectrum for production of delayed light by the red algae has one peak at 550 mµ with a shoulder from 600 to 660 mµ.
4. The emission spectra of the delayed light from both the blue-green and red algae were the same as from the green algae, Chlorella.
5. The action spectra for the production of delayed light by the different species of purple bacteria tested consisted of one or more bands not resolved between 800 and 900 mµ.
6. The emission spectrum of the delayed light from the purple bacteria was largely at wave lengths longer than 900 mµ.