204 Payers from the Department of Marine Biology. 



If the whole colony be stimulated by weak induced shocks, there is 

 a local production of light. There is usually no response to a single 

 shock, but a ready response to three or more sent in in rapid succession. 



With stronger stimuli, a wave of hght, easily followed by the eye, 

 passes over the colony in each direction from the point stimulated. 

 With interrupted induced shocks, a series of waves of light follow one 

 another in quick succession (not corresponding to the number of 

 stimuli, however), reminding one of the series of electric shocks given 

 out by the torpedo, only on a slower scale. The time-interval between 

 separate flashes no doubt corresponds to the refractory period of the 

 cells concerned. 



On pressing deeply into the tissue and stimulating strongly, a much 

 brighter light-response also results, which very slowly moves away 

 from the point of stimulation and usually does not extend more than 

 2 or 3 cm. At the same time the whole colony contracts, the polyps 

 are drawn in, and in this condition do not respond to electrical stimu- 

 lation by light-production. 



The wave of light above mentioned will pass in any direction over 

 the colony and across a cut around the middle of the colony involving 

 the whole of the external tissue. Some inner tissue must therefore be 

 capable of conducting the stimulus. 



LACK OF OXYGEN. 



That the production of light by Cavernularia is an oxidation can be 

 very readily determined by passing a current of hydrogen through the 

 juice, when the light disappears, but promptly reappears upon admit- 

 ting oxygen. A sample of phosphorescent juice kept 24 hours in an 

 atmosphere of hydrogen gave light when air was admitted. 



Considerable oxygen is necessary, as may be seen by keeping the 

 juice in a tall test-tube, when it Ughts only at the surface in contact 

 with air. The light appears through the tube, however, if mixed with 

 air. 



REDUCTASE. OXIDASE. AND CATALASE. 



A tube of Cavernularia juice shut off from the air very quickly reduces 

 (decolorizes) methylene blue. The blue color reappears when oxygen 

 is admitted. This reaction has nothing to do with Ught-production, 

 however, as it is given also by a non-luminous sea anemone {Anthopleura 

 xanthogrammica) and many other animal tissues which can not produce 

 hght. 



Unboiled Cavernularia juice also gives oxidase reactions upon addi- 

 tion of H2O2 with guaiac, pyrogallol (slight), a-napthol, para-phenylen 

 diamine, indo-phenol reagent, ortol, and pyrocatechin. The boiled 

 juice gave a slight positive test with guaiac, para-phenylen diamine 

 and the indo-phenol reagent. Many other non-luminous tissues give 

 these reactions, however, and there is abundant evidence to show that 



