12 Dr. & tlic Rev. S. Graham Brade-Biiks— 



and he concluded that it was not merely oxidation in progress 

 that produced the lij^ht ; he found that tlie secretion stopped 

 •flowing if dried and began jjlowin;;; again on the addition 

 of water. The secretion was acid, and so tlie hypothesis of 

 llailzizewski, which explained animal luminosity as a slow 

 oxidation in an alkaline medium, is shown, Dubois says, to 

 be incorrect. Dubois considered that the oxygen permitted 

 the respiration of the protoplasmic cor|)uscles passing from 

 a cciUoidal to a crvstalline condition — that is, from life to 

 death ; hydrated protoplasm is needed for the proper activity 

 of tljis respiration, and water is necessary for crystallisation 

 to take i)lace under conditions favourable to the emission of 

 light. Oxygen serves to produce the crystallisablc sub- 

 stance and water allows of photogenic crystallisation. These, 

 he maintains", are two successive states of one and the same 

 substance, modified by oxygen and water. 'I'his substance 

 he teruis luciferln. 



Dahlgren (4), passing the work on luminous centipedes in 

 review, mentions some of the researches we have already 

 noted. He also records (4 c) that Thomas found a species 

 of Geojjhilns being attacked by ants. The ccnti[)cde was 

 throwing out masses of slim^'^ light material which adhered 

 to the ants. 



Up to the time of our own thirteenth paper (2) we were 

 Mot familiar with living luminous centipedes, and in our last 

 l)aragrai)h on the subject of luminosity we spoke of our 

 familiarity with Geophihts carpophdyus, Leach, in South 

 Lancashire, mentioning that we had never noticed it luminous 

 there. Li Kent it is commonly luminous. We thereupon 

 concluded that the i)henomenon was hardiv likely to be in 

 any way essential to the well-being of the animals, but that 

 it seemed more likely to be due to conditions of nutrition 

 and envirounuMit, a view which seemed to be supported by 

 the fact that Kent observers who had kept some luminous 

 centipedes in captivity iound that their powers of exhibiting 

 phosphorescence upou stimulation gradually declined, and 

 generally disappeared in the course of three days. 



From the foregoing accounts of observations and opinions 

 it will be seen that chaos must reign in the reader's mind 

 after })erusing the literature. The next section of this 

 paper, which deals with our own observations, is intended 

 to gather together the main threads of our knowledge of the 

 .subject, and to indicate the lines upon which subscijuent 

 research should {jroeeed. 



As early as JHO.'L*, Phipson published a book (11) on 

 'Phosphorescence,' in which a short cha[)tcr is devoted to 



