48 HIDDEN BEAUTIES OF NATURE 



to the discovery of the secret. Results have been 

 produced, by experiments with oxygen and alkaline 

 reaction, which resemble the phosphorescent energy 

 of the creature. But in all such laboratory experi- 

 ments for generating light an amount of heat was 

 developed, denoting a process of oxidation, and 

 hence burning. Whereas the most delicate tests 

 that have been applied to those creatures which 

 have the greatest power of emitting light have 

 failed to detect any increase in temperature. Panceri 

 made many experiments upon the rock-boring pholas 

 of the Mediterranean, and to make his researches 

 more accurate, he used the electric thermo-pile, 

 which could register far more accurately than any 

 thermometer the least increase in temperature. But 

 he failed to detect any change during the emission 

 of light. We are compelled to admit that though 

 we may produce a light which has the appearance 

 of that produced by the hosts of creatures in the 

 oceans, yet it is quite different, and we have, as yet, 

 failed to find the process by which even small 

 creatures emit their remarkable glow. 



It was thought by Mary Somerville that the 

 luminous effect produced by marine creatures might 

 be the result of involuntary nervous contraction, 

 and if so, ' then the light must be electric.' Darwin, 

 in his Voyage of the Beagle, says : ' While sailing a 

 little south of the Plata on one very dark night, the 

 sea presented a wonderful and very beautiful spec- 

 tacle. There was a fresh breeze, and every part 



