ON THE INHIBITION OF ANIMAL LUMINESCENCE 



BY LIGHT. 



E. NEWTON HARVEY. 1 

 PRINCETON UNIVERSITY. 



Since Allman's (1862) observations on Ctenophores, many re- 

 searches have left no doubt of the inhibition of the luminescence of 

 these forms by light. There is not only inhibition of the irrita- 

 bility but an actual disappearance of photogenic substance, 

 which will return again in the dark, even in extracts of Cteno- 

 phores, provided the photogenic cells have not been entirely 

 broken up. But a centrifuged extract of Ctenophores exposed to 

 sunlight shows only slight recovery of its power to luminesce in 

 the dark, as compared with a control kept continually in the 

 dark. The centrifuged extract contains photogenic granules but 

 not photogenic cells, and I think it doubtful if isolated granules 

 recover the power to luminesce, although this point is difficult 

 to ascertain with certainty. 



Heinemann (1872) observed inhibition of the luminescence of 

 Pyrophorus, the West Indian elaterid, and I have observed 

 marked inhibition of the luminous extract of Cypridina (Harvey, 

 1925) but none of the whole living animals themselves. 



Massart (1893) found a day and night periodicity of lumi- 

 nescence in Noctiluca, Zacharias (1905) in Ceratium, B. Moore 

 (1908) in some animals of the plankton, presumably copepods, 

 and Heymans and A. R. Moore (1923) in Pelagia noctiliiui. a 

 medusa. It is reported that these forms will not luminesce in 

 the daytime even when they have been kept in a dark room. 

 In a recent note A. R. Moore (1926) was unable to confirm the 

 observations of Heymans and Moore in Pelagia and I have also 

 been unable to observe any inhibiting effect of strong sunlight 

 on either the local or general luminescence of this form, although 

 the exposure was from sunrise until noon of a cloudless day in 

 December. Parker (1920) finds inhibition of luminescence <f tlu- 

 pennatulid, Renilla, by sunlight. 



1 Appointed to the A. A. A. S. table at Naples, Oct. ipas-Feb. 1926. 



85 



