184 



Papers from the Department of Marine Biology. 



The luminous material of Cypridina, like that of most luminous 

 organisms, is unaffected by cold and will glow brilliantly at 0° C. 



STABILITY. 



Cypridina photogenin is much more stabile than photophelein. The 

 time after preparation that one can obtain light from these substances 

 depends largely upon their concentration, as also upon the temperature. 

 One sample of concentrated (1 Cypridina to 2 c.c.) photogenin gave 

 light with fresh photophelein for 7 days at 20°, despite the fact that 

 decomposition had taken place and the Uquid smelled foul. Dilute 

 photogenin (1 Cypridina to 50 c.c.) may lose its power in 1 day; very 

 dilute photogenin (1 Cypridina to 12,500 c.c.) in less than 2 hours. 



Cypridina photophelein also disappears from solution spontaneously, 

 and the more dilute the solution the more quickly does it lose its power 

 to phosphoresce. With one Cypridina to 25 c.c. the power disappears 

 in 3 to 4 hours, while with 1 Cypridina to 1 c.c. it may last for 5 days 

 at 26° to 28° C. 



The decomposition occurs whether the solution be neutral, acid 

 (n/8000 HCl), or alkaline (n/4000 NaOH), in pure-water or sea-water, 

 in the light and also in amber bottles, and occurs even if the photo- 

 phelein be thoroughly boiled to destroy all traces of photogenin which 

 might slowly use up the photophelein without light-production (see 

 p. 189). 



The photophelein is apparently oxidized, as the destruction is not 

 so rapid in absence of oxygen. 



Table 4. — Effect of preservatives on photophelein. 



'Often photophelein will not la.st for one day. 

 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. 



