198 Papers from the Department of Marine Biology. 



disappears in contact with this substance in non-luminous parts, but 

 without Ught-production. In this respect the firefly agrees perfectly 

 with Cypridina. 



Among non-luminous forms we find some whose extract will give 

 light with photogenin, whether boiled or unboiled; others whose extract 

 will give no light, whether boiled or unboiled. The first mentioned 

 presumably contain photophelein not readily destroyed by standing, 

 the second are similar to the firefly, and the third may contain no pho- 

 tophelein or some substance very quickly destructive to photophelein 

 or an excess of acid or perhaps merely unstabile photophelein. The 

 exact reasons have not yet been worked out. The following extracts 

 were tried: 



Luciola photogenin X caterpillar (sp?) blood Bright. 



Luciola photogenin X caterpillar (sp?) blood, boiled Bright. 



Luciola photogenin X beetle {Coccinella 7-punclata) extract Negative. 



Luciola photogenin X beetle {Coccinella 7-punctata) extract, boiled Bright. 



Luciola photogenin X beetle {Glysiphana jucunda) extract Negative. 



Luciola photogenin X beetle {Glysiphana jucunda) extract, boiled Bright. 



Luciola photogenin X beetle {Anomala rufscuprea) extract Negative. 



Luciola photogenin X beetle {Anomala rufscuprea) extract, boiled Negative. 



Luciola photogenin X grasshopper {Pachytylus danicus) extract Very faint. 



Luciola photogenin X grasshopper {Pachytylus danicus) extract, boiled Faint. 



Luciola photogenin X myriapod {Scolopendra sp?) extract Faint. 



Luciola photogenin X myriapod {Scolopendra sp?) extract, boiled Faint. 



Luciola photogenin X ox-blood extract (boiled or unboiled) Negative. 



Luciola photogenin X neutral potato-juice (boiled or unboiled) Negative. 



Note that the oxidases of blood or potato-juice will give no light 

 with photogenin and that they also will give no light with photophelein, 

 even if we add H2O2. As we shall see later, although the oxidases can 

 oxidize pyrogallol with fight-production, they have nothing to do with 

 fight-production by animals (see p. 232). 



As we have already seen (p. 182), Cypridina photophelein, if con- 

 centrated, win give a very faint light with firefly photogenin, and vice 

 versa. Firefly photogenin and luminous bacteria prepared in the 

 proper way (p. 214) or Watasenia scintillans photophelein (p. 223) 

 also give a faint light, but the converse experiment fails to produce 

 fight. Cavernularia photophelein gives no light with firefly photo- 

 genin, but the converse experiment (p. 205) does. At most the light 

 produced in any of these cross-experiments between distantly related 

 species is very faint and again shows that photogenin and photophelein 

 from different luminous forms possess a certain degree of specificity. 

 As was to be expected the different combination mixtures of these 

 substances in various genera of the Lampyridse aU give light as weU as 

 the reciprocal combinations between Lampyrida3 and Elateridse {Pyro- 

 phorus) . Indeed, it may be found that the photogenins from different 

 forms exhibit differences in light-giving power, depending on relation- 

 ship, siroilar to the differences in the hemoglobins, or similar to the 

 specificity of the precipitin reactions of different animals. 



Photophelein, on the other hand, will not give light with extracts of 

 any non-luminous forms or with any chemical substances. 



