ELEMENTARY VITAL PHENOMENA 



255 



the cell-metabolism, although R. Dubois ('92) has shown that in 

 certain animals, e.g., the boring mussel Pkolas, the substance can 

 be extruded from the body as a cell-product without immediately 

 losing its luminous power. Phosphorus is an active poison 

 for all living substance ; hence, in the free state, in which it 

 becomes luminous, it is wholly incompatible with the life of the 

 cell. A trace of free phosphorus or luminous compounds of phos- 

 phorus has never been found in luminous animals. Nevertheless, 

 it can be stated with certainty that the luminosity of living 

 substance is associated, as in phosphorus, with very slow oxida- 

 tion-processes. This follows especially from the fact that the 

 light continues only in the presence of oxygen. Moreover, Fabre 

 ('55) has found that the luminous mushroom, Agaricus, produces 

 much more carbonic acid, when emitting light, than at other 

 times. Finally, there belongs here a fact that was observed by 



O.35 . OAO 



0.50 



Q.6O 



O.7O 



;Fio. 113. /, Solar spectrum ; ///.spectrum. Pyropliorus noctilucus. (After Langley and Very.) 



Max Schultze ('65) in the cells of the photogenic organs of light- 

 ning-bugs, namely, that these photogenic cells stand always in the 

 'closest connection with the tracheae, which serve as breathing- 

 tubes ; and, if they be placed under the microscope with perosmic 

 acid, they withdraw oxygen from the latter, a fact which may be 

 recognised by the appearance of a black precipitate. The photo- 

 genic cells, therefore, absorb oxygen actively. Pfliiger appropriately 

 says concerning it : " Here, in the wonderful spectacle of animal 

 phosphorescence nature has given us an example that shows 

 where the taper burns that we call life." " It is certainly no rare 

 exception, but only the special expression of the general law that 

 all cells are burning continually, although with our corporeal eyes 

 we do not see the light." 



As regards the special processes of oxidation with which the 

 luminosity of living organisms is associated, at present, with our 

 very scanty knowledge of metabolism, almost nothing can be said 

 with certainty. The beautiful researches of Radziszewski ('80) 



