2. If the luminous secretion stands, the light disappears, and if we now add an extract of cypridinas heated to boiling, the light again returns—i. e., Cypridina gives a luciferin-luciferase reaction similar to Pholas dactylus, as described by Dubois.
3. Contrary to Dubois's theory, the luciferase is the source of the light, and not an enzyme causing light-production by oxidation of luciferin, because we can obtain light from luciferase by substances incapable of oxidation (NaC1, chloroform, ether, etc.). The new names of photogenin or light-producer for luciferase and photophelein or light-assister for luciferin have therefore been proposed.
4. Oxygen is necessary for light-production.
5. Both photogenin and photophelein will pass a Pasteur-Chamber land or Berkefeld filter easily.
6. Photophelein dialyzes readily through heavy parchment or collo dion, photogenin with great difficulty or not at all, even after a period of 36 hours.
7. Both photogenin and photophelein are adsorbed by boneblack and 8. The light-producing substances may be dried and thoroughly extracted with ether without impairing their light-giving power.
9. Chemical tests on the natural light-secretion give negative results, since a very small amount of light-substance gives a bright light and at least 1 part of photogenin or photophelein in 1,700,000,000 parts water will give a visible light.
11. Photophelein occurs in extracts (both boiled and unboiled) of many non-luminous organisms, in greatest quantity in Lepas anatifera. The photophelein of Lepas anatifera does not disappear on standing.
12. Pure protein solutions (peptone, Na nucleoproteinate, albumen, etc.) or dried mammalian blood do not contain photophelein, but urine contains a similar body.
13. While photogenin will give light with many substances known and unknown, photophelein will give light only with the photogenin of luminous organs.
14. Cypridina photogenin will give no brighter light with extracts (photophelein) of other luminous forms (Luciola, Cavernularia, Nocti Luca) than with extracts of non-luminous forms, and photo genin will not give so bright a light with Cypridina photophelein as with boiled extracts of non-luminous insects. We must conclude that the two substances are not specific for luminous forms, although there is a certain amount of specificity, for photogenin gives the best light with photophelein from the same species.
15. Bright light can be formed by Cypridina at 0° C. Photogenin
is destroyed above 70°, the temperature and time depending on the concentration; photophelein only after several minutes' boiling, the time depending also on the concentration. The natural luminous secretion ceases to light at 52° to 54°, but the light returns on cooling.
16. Photophelein is relatively unstabile and disappears on standing, the time depending on the concentration. Photogenin is much more stabile, but also disappears slowly.
17. The spontaneous decomposition of photophelein is retarded (perhaps prevented) by lack of oxygen, but hastened by addition of preservatives (chloroform, ether, benzol, thymol). Photogenin can be kept longer by addition of preservatives. One sample preserved with chloroform retained its power to give light with photophelein for over 56 days at room temperature.
18. Saturation with ether, chloroform, benzol, thymol, or chloretone does not affect the light from a mixture of photogenin and photo phelein. Saturation with butyl alcohol or 20 per cent ethyl aclohol or 16 per cent acetone extinguishes the light, and if the mixture is diluted with water the light reappears. This phenomenon of anes thesia of a solution is given by photogenin filtered through porous porcelain plus photophelein and difficultly soluble butyl alcohol, so that it can not be due to the presence of cell fragments or to insolu bility in the 20 per cent ethyl alcohol.
19. Picric acid, tannic acid, and phosphotungstic acid extinguish the light in very weak concentrations, and the light returns in the case of picric acid if the solution is diluted with water. In the case of tannic and phosphotungstic acids, the light returns after first disap pearing, even without diluting.
20. HC1 between n/2000 and n/4000 and NaOH between n/250 and n/500 extinguish the light, and the effect is reversible upon neutrali zation. It can be shown that both HC1 and NaOH affect the photo genin more readily than the photophelein and that the effect of NaOH especially is more readily reversible.
21. KCN does not inhibit light-production even in strong concen tration.
22. Saturation with (NH4)2SO4, NaCl, or cane-sugar extinguishes the light most readily in the order named, and the effect is reversible except in case of (NH4)2SO4 (due to acidity).
23. In the natural secretion of Cypridina or in the whole animal there is always enough photogenin to completely use up the photo phelein. The photogenin from one animal will use up a large addi tional amount (at least 100 times the concentration in one animal) of photophelein, but not an indefinite amount, so that photogenin is not a true enzyme in the strict sense of the word, unless it be an enzyme poisoned by its own reaction products. The photogenin-photophelein system resembles the zymase-cozymase system to a remarkable degree, but it is best for the present to regard photogenin not as an enzyme but only as a substance auto-oxidizable only in presence of photophelein.