We have recorded _in vivo_ emission and time-resolved spectra of the firefly species _Pyrophorus noctilucus_. The emission spectrum shows the FWHM value for this particular species to be 55 nm, which is significantly smaller than the half widths reported till now. The time-resolved spectrum reveals that a flash, of duration about a hundred milliseconds, is in fact composed of a number of microsecond pulses. This result suggests that the speed of the enzyme-catalyzed chemiluminescence reaction in the firefly for the emission of light is much greater than is believed to be. |