5. Oxidation in ozone. (Many organic substances.) 6. Oxidation in acid permanganate. (Pyrogallol.) 7. Oxidation in persulfates and perborates. (Formaldehyde, paraformaldehyde.) 8. Oxidation in perchlorates, periodates, and perbromates. (Palmitic acid.) 9. Combination of 2 and 4. (Many organic substances.) 10. Combination of 3 and 4. (Many organic substances.) 11. Oxidation with H_{2}O_{2} and hæmoglobin or vegetable oxidases. (Pyrogallol, gallic acid, lophin, esculin.) 12. Oxidation with H_{2}O_{2} and MnO_{2}, Fe_{2}Fe(CN)_{6} Mn(OH)_{2} + Mn(OH)_{3} Ag_{2}O, chromium oxide, cobalt oxide. (Pyrogallol.) 13. Oxidation with H_{2}O_{2} and ferrocyanides, chromates, bichromates, permanganates, Fe salts, and Cr salts. (Pyrogallol, esculin.) 14. Oxidation with H_{2}O_{2} and collodial Ag. Pt. Pd. Au. (Pyrogallol.) The spectrum of chemiluminescent reactions has been described in a few instances as continuous but no definite measurements of its extent have been made. Radziszewski (1880) found the light of lophin oxidized in alcoholic caustic alkali, examined with a two-prism spectroscope, to give a continuous spectrum, brightest at _E_, with the red and violet ends lacking. Trautz (1905, p. 101) states that the pyrogallol-formaldehyde-Na_{2}CO_{3}-H_{2}O_{2} reaction gives a continuous spectrum from the red to the blue green with maximum brightness in the orange. Weiser (1918 _a_) has studied the spectra of some chemiluminescent reactions by photographing the light behind a series of color screens. He finds also that the spectra are short, with maximum intensity in various regions. Thus, _amarin_ oxidized by chlorine or bromine, extends from the yellow to greenish blue with a maximum in the green while _phosphorus_, dissolved in glacial acetic acid and oxidized with H_{2}O_{2}, luminesces from yellow green to violet. The spectra of luminous animals are quite similar to those of chemiluminescent reactions. Moreover, as we have seen, chemiluminescence is essentially an oxyluminescence, since oxygen is necessary for the reaction. All luminous animals also require oxygen for light production. Therefore, bioluminescence and chemiluminescence are similar phenomena and they differ from all the other forms of luminescence which we have considered. The light from luminous animals is due to the oxidation of some substance produced in their cells, and when we can write the structural formula of this photogenic substance and tell how the oxidation proceeds, the problem of light production in animals will be solved. CHAPTER III PHYSICAL NATURE OF ANIMAL LIGHT