STUDIES ON BIOLUMINESCENCE. 2X7 



Sponges kept in sunlight for one half hour gave as good a lumi- 

 nescence as those in the dark. 



Whether this is a true luminescence or whether due to luminous 

 organisms living on the sponge cannot be definitely stated. The 

 sponge could not be stimulated to luminesce electrically (inter- 

 rupted induced currents) under conditions when jelly-fish 

 showed a good luminescence. Examined under the microscope, 

 no hydroids, radiolaria, dinoflagellates or Noctilucte could be 

 observed, but many desmids, diatoms, worms and infusoria. 

 These forms are not luminous, however. 



When squeezed through cheesecloth a luminous extract was 

 obtained, the light coming from points of light in the extract as in 

 the case of Cavernularia or medusje. Addition of fresh water or 

 saponin causes a great increase in light just as in extracts of 

 ccelenterates. No luciferin or luciferase could be demonstrated. 



The fact that an extract of this sponge made by squeezing 

 through cheesecloth remains luminescent for some time is signif- 

 icant. If the light came from small luminous forms living on the 

 sponge, we should expect them to pass through the meshes of the 

 cheesecloth unharmed and then light would appear in the extract 

 only on stimulation by agitation or in some other way. It is also 

 significant that no inhibitive effect of sunlight was to be observed. 

 Sunlight is said to inhibit the luminescence of many small 

 organisms, especially dinoflagellates, which might live on the 

 sponge. In general characters, the extracts so closely resemble 

 those obtained from ccelenterates that 1 am inclined to believe 

 the light of this species of sponge is a true luminescence. 



LITERATURE. 



1. Panceri, P. 



'72 Ann. d. Sc. Nat., XVI. 



2. Harvey, E. N. 



'17 Amer. Journ. Physiol., XLIL, 349. 



3. Dahlgren, U. 



'16 Journ. Franklin Inst., Feb. 



4. Allman, G. I. 



'62 Proc. Roy. Soc. Edinb., IV., 518. 



5. Peters, A. W. 



'05 Journ. Exp. Zool., II., 103. 



