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Distribution of Photophelein and Photogenin in Organisms

light, non-luminous, extract, cypridina and extracts

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Certain fundamental facts for the chemical theory of light-production appear when we study the distribution of photophelein and photogenin: (I) in the non-luminous parts of Cypridina; (n) in the non-luminous Cypridina; (in) in other non-luminous organisms; (Iv) in luminous organisms.

By a careful, quick scissors-cut, the head end of Cypridina containing the luminous gland can be separated from the posterior half without any contamination of the latter with luminous secretion. If we now test the non-luminous half with dilute photophelein and photogenin, we find that it contains nothing which will give light with photophelein, but something which will give a bright light with photogenin. We must try the experiment immediately, because this substance disappears if the extract stands in presence of oxygen. In absence of oxygen, or if the extract is boiled immediately (but not too long a time), the sub stance does not completely disappear, even after an hour. There is, therefore, in the non-luminous parts, the substance photophelein, which disappears even in the absence of photogenin (from luminous gland), unless the solution be boiled or oxygen excluded. (Note the similarity to the disappearance of photophelein in the presence of photogenin, with this exception, that no light is produced.) The experiment seems to indicate a third substance destroyed by heat, in non-luminous parts, which oxidizes (since oxygen is necessary) the photophelein.

In the extract of the non-luminous species, there is also a similar substance (photophelein) which will give light with photogenin. Unlike the photophelein from the non-luminous part of Cypridina hagendorfiti, it occurs in very mall concentration, so that we must use concentrated' photogenin and concentrated extract of Cypridina x.

The photophelein from Cypridina z is also destroyed or disappears if the extract stands 14 hours in contact with oxygen, but not in the absence of oxygen. Boiling makes the extract more stable.

In some other non-luminous forms, widely different in relationship from Cypridina, there are substances which give light with concen trated photogenin and others which will not, whether the extract has been boiled or left unboiled. The extracts were boiled in order to destroy substances which in turn might quickly destroy photophelein.

Among the light-giving extracts may be mentioned those listed in table 2.

Of these forms, Lepas and Chiton gave the best light and of these two only Lepaa gave light with dilute Cypridina photogenin. Too much stress must not be laid upon comparative results, because much depends upon the concentration and it is not easy to obtain extracts of comparative concentration.

Unlike the photophelein from the luminous parts of Cypridina or from non-luminous cypridinas, that of Lepas extract or of Dolabella blood is perfectly stable and will give light with photogenin even after standing for a period of 24 hours.

Many extracts were found to give no light with concentrated photo genin. These included those shown in table 3, which were tried both boiled and unboiled. Again it is possible that with greater concen trations even these extracts would call forth a faint light.

The following fluids and dissolved protein substances also give no light when their solutions are mixed with photogenin: 50 per cent egg albumen; 50 per cent egg yolk; Na nucleate; Na nucleoproteinate; Witte's peptone; neutral meat peptone; dried ox-blood extract.

It is certain, then, that there is photophelein or something similar to it in the blood or extracts of many invertebrates, but not necessarily in solutions of protein substances such as egg albumen, peptone, etc. In saliva there is something giving a very faint light and something in urine giving a fairly bright light with photogenin. Certain fluids tried were sufficiently acid to prevent the appearance of light and some fortuitous characteristic, such as acidity, may explain why extracts of some invertebrates give no light with photogenin.

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