PRESERVATIVES AND ANESTHETICS.
The addition of preservatives (anesthetics), as chloroform, ether, benzol, and thymol, is to hasten the spontaneous destruction of the photophelein and to preserve the photogenin.
Ether is especially destructive to the photophelein, whereas photo genin will give light after saturation with ether for 22 days. Tables 4 and 5 show the effect of saturation of solutions (1 Cypridina to 25 c.c.) of photophelein and photogenin with the four substances.
The harmlessness of the above anesthetics for Cypridina photogenin is unusual, as Dubois found a marked destructive action on Photos photogenin (luciferase) and I have noted the same thing for the firefly.
As we have just seen, the addition of certain anesthetics does not rapidly destroy photophelein or photogenin. We can saturate a phos phorescent mixture of the two with ether and the light will still last for some time. If we add butyl alcohol to saturation the light disap pears, and if the solution is now diluted with water or sea-water, the light reappears. The same phenomenon is observed if the photogenin be filtered through a Chamberland porcelain filter to remove all traces of cells or cell fragments. Care was taken to make sure that the return of light was not due to fluid adherent to the sides of the test-tube and untouched by the butyl alcohol.
A similar phenomenon is observed with ethyl alcohol and acetone. If we add in small amounts absolute ethyl alcohol to a glowing mixture of photogenin and photophelein, the light becomes very dim when 16 per cent alcohol has been added and disappears with 20 per cent alcohol. If now the mixture be diluted, the light returns. Acetone' behaves as alcohol. About 23 per cent is necessary for extinction of the light. Saturation with chloretone does not extinguish the light.
The effect of ethyl alcohol and acetone might be explained as the effect of precipitation, because of insolubility in the 20 per cent solu tion, but we can not so explain the extinction of the light by butyl alcohol and subsequent recovery on dilution, since butyl alcohol is only soluble to the extent of 8.3 parts in 100 parts of water. We are dealing with a highly interesting effect—one akin to anesthesia—a reversible inhibition, not of a cell or cell fragments, but of a solution. Filtration through porous porcelain shows that no cell fragments can be present. I can not here enter more fully into a discussion of this interesting phenomenon, whose bearing on anesthesia is obvious, except to point out that if we can anesthetize a solution we need not, as some recent theories have done, regard changes in the cell-membrane to be neces sarily the ultimate cause of anesthesia.
It may be pointed out in passing that the production of light gives us the opportunity of observing the effect of, let us say, an anesthetic or temperature upon a process at any particular instant, rarely ob tained in the study of enzyme action or even of cell action, except where some movement is affected. For instance, we can heat pepsin to 60° and then cool it and see if it will digest protein. If we find that it will digest protein, that gives us no information as to a reversible inhibition at 60°, an inhibition which might become non-reversible if we kept the pepsin at long enough to test directly the power of digestion. We can, however, heat photogenin and photophelein to 60°, cool them, and find out immediately if they give light.