LIGHT BY LIVING ORGANISMS McDERMOTT. 349 



chemiliiHiinescence, and tho fact (to bo referred to in the next section) 

 that tho luminous tissues may be removed from the organism and desic- 

 cated and still induced to produce light under certain circumstances, 

 confirms the view that the only essential difference between the two 

 phenomena is that biophotogenesis takes place in a living organism 

 instead of a test tube. 



A comparison of the spectral ranges of the light from different 

 organisms is of some interest, and the accompanying chart has been 

 compiled from data from the references given, and redrawn to a 

 uniform scale, the extreme left-hand end representing wave length 

 0.70/1 and the extreme right-hand end wave length 0.39/t; a few of the 

 more important Fraunhofer lines are shown in the first spectrum, and 

 the sodium D line is continued through the series by the dotted line. 



2. THE CHEMISTRY OF THE PHOTOGENIC PROCESS. 



Our knowledge of the chemical processes involved in biophoto- 

 genesis is rather meager. It is fairly well established that all photo- 

 genic organisms require at least two constant chemical factors in 

 addition to the specific photogenic substance in order to exhibit 

 their luminous property, viz, the presence of oxygen and of moisture. 



Dubois's ( 17 > 18 ) theory assumes the oxidation of a substance of un- 

 known composition, to which he has given the name "luciferine," 

 through the agency of the oxidase "luciferase." Prof. Kastle in his 

 monograph on "The Oxidases and Other Oxygen-Catalysts Con- 

 cerned in Biological Oxidations" ( 34 ) refers to tins claim of Dubois 

 that the photogenic process in organisms involves the action of 

 "luciferase." Prof. Kastle's observations on this point led him to 

 believe that no oxidase was present, but that peroxidase and catalase 

 were present; he found that aqueous extracts of the luminous tissue 

 of the common firefly failed to turn tincture of guaiacum blue, 

 except in the presence of hydrogen peroxide, and the bluing in the 

 presence of the latter was accompanied by the rapid disengagement 

 of oxygen. Quite recently Dubois ( 20 ) has put forth the view that 

 luciferase is a peroxidase, for the reason that it can be replaced to 

 some extent by hydrogen peroxide. Loew ( 40 ) found that the lumin- 

 ous tissue of the firefly showed no greater catalase activity than 

 other tissues from the same insect. Lund ( 42 ) has made similar 

 observations on the enzymes in these insects. Until more definite 

 data are at hand, it would seem that the enzyme theory requires 

 some caution in acceptance, but the facts so far as known certainly 

 present some analogy to other known biologic processes of an enzy- 

 motic nature, and it is not at all impossible that his explanation 

 may be correct. Watase" ( 70 ) expresses the view that in Noctiluca 

 miliaris and other simple luminous forms the "phosphorescence" 



