208 Papers from the Department of Marine Biology. 



faint glow upon dilution of the solutions with sea-water. The alcohols 

 give similar results. About 16 per cent ethyl alcohol will cause the 

 light to disappear in one minute, but there is no recovery or only a very 

 faint momentary glow on diluting with sea-water. Saturation with 

 butyl alcohol gives a similar result. 



Since reversibility is the sine qua non of anesthesia, we must conclude 

 that this juice can not be anesthetized, in this respect differing mark- 

 edly from the granule-free Cypridina luminous secretion which can be 

 anesthetized by the alcohols. Also many luminous organisms — for 

 instance, luminous bacteria — can be truly anesthetized (see p. 219). 



POTASSIUM CYANIDE. 



Potassium cyanide has no inhibiting effect upon the light-production 

 of Cavernularia juice. Even in m/40 concentration the light is still 

 bright after 90 minutes, a result agreeing with all other experiments 

 on luminous organisms (bacteria, firefly, Cypridina, Noctiluca). 



SUMMARY OF RESULTS FROM CAVERNULARIA. 



1. The light of Cavernularia comes from a luminous slime, a secre- 

 tion of gland-cells over the outer surface of the colony. 



2. The secretion contains small granules which can be seen to emit 

 the light. On standing the light from a sea-w^ater extract of Cav- 

 ernularia slowly disappears and will not return on shaking, but 

 reappears if fresh water is added to the juice. 



3. The light substance — i. e., the granules — will pass an alundum 

 filter (R A 84) but not a Chamberland filter. It is not adsorbed by 

 boneblack or Fe(0H)3 and will not dialyze. 



4. The light-producing granules do not respond to electrical stimu- 

 lation, but the colony gives hght with galvanic or induced currents. 



5. With galvanic currents a flash appears on the make and a series 

 of flashes while the current is passing, which cease on the break. 



6. Upon stronger stimulation (with induced currents) a wave of 

 light passes over the colony in all directions from the point stimulated. 

 This wave will pass through the deeper tissues when all the ectodermal 

 tissues are cut. 



7. A considerable amount of oxygen is used up in light-production 

 and no light appears in its absence. 



8. Cavernularia juice will decolorize (reduce) methylene blue in 

 absence of oxygen, and it also contains peroxidases and catalase. 



9. The hght is still bright at 0° C. Fragments of Cavernularia give 

 off light spontaneously at 40° C, which disappears at 52° C. and does 

 not return on cooling. 



10. The photogenin-photophelein reaction is not given by Caver- 

 nularia, but a faint light can be obtained with a non-luminous Caver- 

 nularia juice (photogenin) and Cypridina or firefly photophelein. 



