38o RESEARCHES ON FUNGI 



(Pyrosoma) is due to luminous symbiotic bacteria which reside in 

 the luminous organs and pass from one generation to another via 

 the eggs ; and it is suggested that the property of bioluminescence, 

 in reality, is not possessed by any animals but is restricted to Fungi 

 and Bacteria.^ This interesting theory of symbiosis, of which doubt- 

 less we shall hear more in the future, is, as yet, far from being proved. 

 E. N. Harvey ,2 in 1920, rejected its application to Cypridina, an 

 ostracod Crustacean, because the luminous material of the animal 

 will withstand boiling with 20 per cent, (by weight) hydrochloric 

 acid for 6 hours. However, in 1921, the same investigator ^ found 

 bacteria in the very large luminous organs of two fishes, Photoble- 

 pharon and Anomalops, which he examined at Banda Neira in the 

 Dutch East Indies. The bacteria were always present in the organs, 

 and emulsions of the organs glowed brightly in the dark and thus 

 behaved exactly like emulsions of luminous bacteria. Luciferin and 

 luciferase could not be demonstrated as being present and this, 

 again, is characteristic of luminous bacteria. Moreover, the light 

 emitted by the bacteria in the organs was, like the light of fungi 

 and luminous bacteria generally, continuous both day and night, 

 and unaltered by stimulation. Some of the bacteria, which were 

 rod-shaped, when immersed in sea-water, were seen to move of their 

 own accord, often with a corkscrew-like motion. Good growths of 

 bacteria taken from the luminous organs were obtained on peptone- 

 agar, but unfortunately they produced no light. Thus an important 

 link in the chain of evidence required to prove that bacteria are 

 responsible for the light emitted by the two fishes is still lacking. 



The conditions for the emission of light by light-producing 

 animals and plants include the presence of oxygen, water, and some 

 photogenic substance.'^ Boyle, in 1667, proved the necessity of air for 

 the luminescence of rotten wood and fish ; and Spallanzani, in 1794, 

 showed that parts of luminous medusae gave no light when dried 

 but, if moistened again, would emit light as before.^ That lumines- 



^ Vide Paul Buchner, Tier und Pflanze in intrazellularer Symbiose, Berlin, 1921, 

 chap. V, Die Leuchtsymbiose, pp. 340^00. 



2 E. N. Harvey, The Nature of Animal Light, 1920, pp. 14, 74. 



^ E. N. Harvey, The Production of Light by the fishes Photoblepharon and 

 Anomalops, Publication No. 312 of the Carnegie Institution of Washington, pp. 43-60. 



* E. N. Harvey, The Nature of Animal Light, 1920, p. 85. ^ jf^i^^ 



