McDermott — Observations on a Photogenic Micro-organism,, 181 



Forsyth (Nature, 1910, Vol. 43, p. 7) has reported the dis- 

 covery, by spectrophotography, of ultra-violet rays in the light 

 of PhotobacteHum phosphorescens Fischer. This seems very remark- 

 able, especially in view of the fact that ultra-violet light is used 

 as a batericide, and the further fact that previous photographs 

 of the spectrum of the light of these organisms had failed to 

 show the presence of such rays. In this connection solutions 

 and crystals of para-amino-ortho-sulpho-benzoic acid* have 

 been exposed to the light from large cultures of Ps. lucifera, 

 and have failed to show the least trace of fluorescence, although 

 this substance is used to detect ultra-violet radiation by means 

 of its fluorescence. It seems very unlikely that this organism 

 emits ultra-violet radiation. 



Luminous cultures of Ps. lucifera on the usual culture media 

 do not appreciably aflect a charged electroscope. For the conduct 

 of the experiments leading to this conclusion, I am indebted to 

 Drs. F. W. Clarke and R. C. Wells, of the Geological Survey. 



In its chemical conduct this micro-organism exhibits only 

 certain slight similarities to the firefly. Professor Kastle and the 

 author have shown that the luminous tissue of the Lampyridae 

 which has been dried in the absence of oxygen — preferably in a 

 hydrogen vacuum — and sealed in hydrogen, will exhibit lumi- 

 nosity when moistened , for at least thirteen months after prepara- 

 tion (Amer. Journal Physiol., 1D10, Vol. 27, pp. 122-151, 

 November), and since the above paper was written, specimens 

 prepared at the same time have glowed on moistening after 

 eighteen months; in fact there seems to be no good reason why 

 they should deteriorate at all . The author has found that if com- 

 mercial hydrogen peroxide solution is used in place of water for 

 moistening the dry material, a much brighter light is obtained, 

 whose spectrum is of about the same range as that of Pi. lucifera, 

 though with its point of maximum intensity nearer the yellow. 

 (Canadian Entomologist, November, 1910, Vol. 42, pp. 357- 

 363.) Somewhat similar observations may be made upon this 

 micro-organism. An open vessel tilled with sulfuric acid was 

 placed upon the bottom of a flask, the walls of which were coated 

 with a luminous gelatin culture of Ps. lucifera, the flask filled 

 with hydrogen, tightly stoppered, and set away. After two 



* Kindly sent me by Prof. . I. H. Kastle of the University of Virginia (See American 

 Chemical Journal. January. 1911 >. 



