THE METABOLISM OF PLANTS. 317 



Fungi are the Agaricus olearius of Southern Europe, the 

 Agaricus igneus of Amboyna (Rumpf), the Agaricus noctilu- 

 cens of Manilla (Gaudichaud), the Agaricus Gardneri of Brazil 

 (Gardner), and various Australian Agarics (Drummond). In 

 all these last-mentioned cases it is the fructification which is 

 luminous and not the mycelium: 



Various statements have been made as to the luminosity of flowers 

 (TropcEolum majus, Oenothera macrocarpa, Calendula officinalis, Lilium 

 bulbiferum, Tagetes patula, Helianthus, Polyanthes, Phytolacca decandra}, 

 but, even admitting the accuracy of the observations, the phenomenon 

 in most of these cases is different from that described above. The lumir 

 nosity spoken of above is persistent, whereas in the case of most of these 

 flowers it consists of sudden flashes, in fact it suggests an electrical dis- 

 charge. In some of the cases (Oenothera, Phytolacca, Polyanthes) the 

 luminosity was persistent, but it might have been due to the presence of 

 luminous Fungi. (For Literature of the subject see Fries, Meyen, de 

 Bary, and Pfliiger.) . . 



Among Algae Meyen mentions a species of Oscillatoria, occurring in 

 masses in the Atlantic ocean, and Ehrenberg certain species of Diatoms, 

 of the genera Chsetoceras and Discoplea, as being luminous : Ducluzeau 

 speaks of luminous Confervas, and Brewster states that he observed 

 luminosity in Chara vulgaris and hispida. But these statements all 

 require investigation ; the luminosity of Chara mentioned by Brewster is 

 almost certainly due'to the phosphorescence of the calcium carbonate 

 with which the plants are encrusted. 



The evolution of light is essentially dependent upon the 

 life of the organism ; thus Fabre observed that the luminosity 

 of a specimen of Agaricus olearius was destroyed when the 

 plant was killed by dipping it into water at 5OC. t Further, 

 the evolution of light is dependent upon the destructive meta- 

 bolism of the plant. Bischoff found, for instance, that the 

 luminosity of Rhizomorpha is not exhibited in vacua or in 

 an atmosphere destitute of free oxygen, and his results have 

 been confirmed by all subsequent observers in the case of 

 other Agarics and of Bacteria : thus Ludwig ascertained that 

 Rhizomorpha remains luminous in water which has not been 

 boiled, whereas- it at once loses its luminosity in boiled water, 

 in water, that is, which holds no air in solution. Fabre found, 

 in one experiment, that a given weight of Agaricus olearius 

 exhaled more carbon dioxide than an equal weight of the 



