Three species of luminous bacteria were injured or destroyed by a variety of modifications of four general methods: (a) cytolysis with fat solvents, (b) osmotic cytolysis, (c) mechanical grinding, and (d) intense sonic vibration. Although all experiments were performed under conditions which would have prevented the oxidation of the bacterial luciferin and which were, in general, favorable for bioluminescence, it was not possible in any case to demonstrate the luciferin-luciferase reaction or obtain luminescence from bacteria whose structure had been materially altered. The conclusion is drawn that bioluminescence, like many other bacterial oxidative phenomena, is closely associated with cellular structure. Respiration and reducing activity were shown also to be greatly affected.