504 History of Luminescence 



In only one respect did Heller go astray. Basing his conclusions 

 on experiments with impure nitrogen and hydrogen in which the 

 light of wood persisted, he came to the conclusion that the origin 

 of the light in the fungus itself was electrical rather than a com- 

 bustion or an oxidation. 



From Heller to Pfliiger 



Although Heller's work on Sarcina noctiluca was clear cut and 

 his ideas correct, an added proof of luminous bacteria as the cause 

 of the luminescence of fish and meat came from the two papers of 

 Eduard Pfliiger (1839-1910) in 1875. His great reputation had 

 much to do with convincing the scientific world. Without a knowl- 

 edge of Heller's work, Pfliiger had studied the older literature, 

 particularly the monograph of Heinrich (1815), and came to the 

 conclusion that the light must be the result of living organisms. 

 Microscopic observations, showing great numbers of bacteria in the 

 luminous slime of fish, and the fact that a filtrate showed no lumi- 

 nescence removed all his doubts. The crucial test came from the 

 inoculation of shellfish and fresh-water fish with luminous material 

 from a marine fish, and the demonstration that the luminous spots 

 would increase in size. Pfliiger also stressed the point that light 

 production was a " Verbrennungsprocess." 



Between Heller (1853) and Pfliiger (1875) a number of observers 

 remained completely unaware of the bacterial origin of the lumi- 

 nescence of flesh. Phipson (I860, 1862: 103) discarded the micro- 

 organism theory of fish luminescence and leaned toward the idea 

 of a luminous grease, a " peculiar organic matter which possesses 

 the property of shining in the dark like phosphorus itself." 



E. Mulder (born 1832) , professor of chemistry at Utrecht, claimed 

 in 1860 that the luminescence of fish began when they started to 

 decompose. He realized that the light did not come from phos- 

 phorus but thought it resulted from the action of hydrogen on 

 phosphorus in organic combination in the fish, giving rise to phos- 

 phine. This conclusion was based largely on a study of the effect 

 of various agents on fish luminescence, whose behavior he found to 

 be the same as on phosphine. He also related the story of an 

 acquaintance who had eaten shrimp that were not fresh. As a 

 consequence the person became ill and his excrement, as well as 

 the remains of the repast, were luminous in a dark room. 



Another skeptic of the bacterial origin of the light of flesh was 

 W. G. Hankel (1862) , a professor of physics at Leipzig. Using the 

 microscope, he was unable to find any evidence of " Infusorien oder 



