50 



the structural proteins and were not all carotenes. Possibly, the dis- 

 appearance of ascorbic acid from the adrenal cortex in increased 

 functional activity is due to the formation of such protein com- 

 plexes. In any case a closer study of these relations seems to be 

 indicated. 



LONG-LIFE EXCITATION IN PROTEINS 



Frozen animal tissues, in the absence of oxygen, show after 

 illumination with the UV lamp a strong and long-lasting after- 

 glow. Pigments interfere with the observation of this light emis- 

 sion which is thus observable only in organs which are poor in 

 colored matter. If, for instance, the brain of a guinea pig is placed 

 in a test tube, the air is replaced by N2 and the tube is im- 

 mersed in the dry ice freezing mixture, if held (after tem- 

 perature equilibrium is attained) before a high pressure Hg lamp 

 for a second it is found to emit an intense bluish-white light 

 which lasts for half a minute or so, and is followed by a weak one 

 lasting for some time more. In the presence of air, that is O2, no 

 such phosphorescence is obtained, nor does the tissue show any 

 such emission at room temperature in N2. Other organs poor in 

 pigment, such as muscle, uterus, intestine, lung, skin, and mam- 

 mary cancer (mice) show the same phenomenon. The emission is 

 not visible in organs which are rich in pigment, as are kidney, 

 liver, or dark muscle (heart). This long-lived phosphorescence is 

 not a specific property of tissues. A 1% serum albumin solution 

 (serum albumin cryst.. Armour), as well as an 1% ovalbumin or 

 gelatin show it too, though in the latter the emission is of shorter 

 duration. 



This long-lived phosphorescence was, to my knowledge, not 

 described before, having been overlooked, probably, owing to the 

 quenching action of the atmospheric oxygen. Debye and Edwards 

 described a long-lived phosphorescence in protein solutions, but 

 note that this phosphorescence, which they observed at the tem- 

 perature of liquid N2, is very sensitive to the elevation of tempera- 



