The bioluminescence is especially interesting for physiologists in the sense that the end of the intracellular mechanism of the light producing cells is revealed by the light. Whole energy liberated by the process is represented by the light only, unmixed by other energies e. g. movement or heat. This special fact simplifies the experiment enormously, because the light intensity can be measured accurately and conveniently. Photometries used for these studies were following two, according for the purpose. a) Photographic method comparing either of the intensity grade or the diameter of the dark spot on the negative plate or film. b) Comparison method of the brightness of the light with the aid of the adjustable dark glasses (double frame detached from the Hess' differential pupilloscope). The results obtained on the Japanese firefly (Genzi-hotaru and Heike-hotaru) were summariesed as follows. 1) The light producing organ kept in exsicator could be brought to emitt light again by moisting with water, even after two years. 2) The spectrum of the light of the Japanese firefly extends continuously from the reddish orange (660μμ) to the bluish green (480μμ). 3) The intensity of the light increases by the stimulation of the light producing organ with the faradic current or by the chemicals which affect only muscle but not nerve. This phenomenon does not suggest the excitability of the organ or the presence of the exciting nerve for the organ, but can be explained by the increased supply of air by the contraction of the tracheal muscle. 4) The light extinguishes at temperature 0°--7°C., it reappears again dy warming. At the temperature over 40°C. the light becomes gradually reddish and extinguishes at 48°C-54°C. It does not reappear by cooling. The temperature coefficient for intervals 10°C. of the light intensity is 1.2-1.3. The same for the velocity of decay of light is 1.9-2.1. 5) Oxygen is indispensable to the light production of the light producing substance of firefly, which does not emit light under 1/40 atomospheric pressure of oxygen. The intensity of the light increases propotional to the oxygen pressure in the extent of 1/40 to I atomospheric pressure; over that pressure the light intensity approaches asymptotic to the maximum. Further increase of pressure beyond the maximum, also until 4-5 atomospheric pressure or even to 15 atm. pr. does not show any tendency to decrease the light intensity. 6) The light emission from the minced light producing organ of the firefly is not affected by carbon monoxide. It shows that the oxidizable substance does not combine with CO more forcible than with oxygen as haemoglobin does. 7) The light is given out, when the hot water extract from the light producing organ or the non-luminous part of the firefly or from certain animals like cocoonworm (Kaikono-Mayu) which have no light producing organ, is added to the cold water extract from the light producing organ of the firefly. 8) HCN-gas has no influence upon light production of the light producing organ or the mixture of cold water and hot water extracts from the light producing organ, the oxidation concerned with the light production by the firefly would refer to other than the oxidation connected with iron. 9) The authers measured the CO(2) production from the isolated light producing part and non-luminous part of the firefly with Osterhout's indicater method applied for the CO(2) -gas measurement of nerve fibre by Parker and came to the conclusion that the oxidation reaction does not accompany with CO(2) production, for the light producing part did not give out more CO(2)-gas than the non-luminous part. 10) The decay curve of the light emitted from the mixture of the hot water extract from non-luminous part of the firefly or from the larva of the Dendrolimus pini (Matu-Kemusi) and the cold
water extract from the light producing part of the firefly indicates that the luminescent reaction in the firefly belongs to a monomolecular reaction, provided, the light intensity at any instant is assumed to be proportional to reaction velocity at that instant. 11) The velocity of the decay of the light intensity which emits from the mixture of cold and hot extract quickens by the increase of the quantity of the cold water extract of the light producing part of firefly. From this fact it seems that the cold water extract contains an enzymlike substance which hastens the luminescent reaction. On the contrary, when the quantity of the hot water extract from luminous part or non-luminous part of the firefly or from non-luminous animals increases, the light of the mixture decays slowly and lasts longer. This fact is explained by an assumption that the hot water extract lets the photogenic substance active (e. g. it sets the inactive photogenic substance combined with protein free.) and at the same time enzymlike substance becomes correspondingly inactive (e. g. by the adsorption). At the addition of the cold water extract into the cold and hot water mixture, it sometimes brightens the emitted light and sometimes lessons it. This initial flash is accounted for granting that the hot water extract acts at bravest at an optimal concentration which is proved especially in case of that from non-luminous part of the firefly. 12) The extinguished but still active cold water extract emits the light by the addition of alkali instead of the hot water extract. On the contrary, we could not let shine the hot water extract by any means. 13) Potassium bromide or erytrosin inhibits luminescence of the light mixture, but Potassium cyanide does not. 14) The active hot water extract is formed by heat from the firefly or certain non-
luminous animals; i.e. by the convertion of the precursor into its efficacious form and by the destruction of material preventing the action of the active substance. Required temparature and time for this purpose is about over 3 min. at 50℃. or 15-16 min. at 100℃.. On the contrary, the active cold water extract loses its power by warming at 42°-43°C. over 3 min. 15) The active hot water extract in solution does not degenerate in half a day, and is efficacious even after a day, but the active cold water extract diminishes in power remarkably in 1-2 hours at room temperature. 16) The active component in the hot water extract passes easily through filterpaper, Chamberand filter and collodium membrane, but the active substance in the cold water extract does not filter through collodium membrane. 17) Charcoal adsorbs the active part both in hot and cold water extracts, but the latter is less adsorbed than the former. 18) Such an efficacious component as that in the active hot or cold water extract can not be extracted by alkohol or ether.