Notes on Mijriapodn. 25 



Upon stimulation, imdcr tlie usual circumstances, mucin, 

 acid, iimX protol II ciferiti are excreted upon the ventral surface 

 of tlic auiiual's l)0(ly into contact with one another and 

 the air with its impurities, and inuncdiately luminosity is 

 produced. 



If the discharj^c he dried Inminosity ceases, but upon the 

 addition of water it is continued ; so that tvater is essential 

 to //ic production of in/lit in Geophilus oarpophagns. 



It should be noted that water will be present in the 

 excretions themselves as a normal constituent of mucin. 



It has generally been accepted in other siniihir cases that 

 atmospheric oxygen was essential to the production oP light. 

 It has already been mentioned that G. carpophafjus can be 

 stimulated to luminesce under water, but atmospheric oxygen 

 might in that case be present, in solution, in the tracheae of 

 the animal's body, or as a film on the surface of tlie body 

 itself. To obviate all these factors a newly made film was 

 introduced into a vessel of water, at the ordiiuiry temperature, 

 boiled previously and so free from dissolved air. Lumino- 

 sity was not inhibited, but continued normally below the 

 surface of the water. Therefore, atmospheric oxygen is not 

 essential for the production of liyJit in the case of Geophilus 

 cai'pophagus. 



A similar ex|)eriment, perhaps less convincing, but con- 

 firmatory, was conducted with the substitution of olive-oil 

 for boiled water. Luminosity again continued below the 

 surface of the oil. With alcohol the excretion was coagu- 

 lated and the luminosity was inhibited almost instantaneously. 



As an outcome of these enquiries, we can add that, in the 

 case of Geophilus carpophagus, under certain conditions all 

 the essentials for the production of light are secreted by the 

 animal itself, and upon the expulsion of these essentials to 

 the exteriur the chemical action which appears to take place 

 in the excretion is accompanied by the production of light. 



The Use of Phosphorescence. 



When we come to consider the utility of light-production 

 in the economy of the life of G. carpophagus, we arc face to 

 face with no mean [)rol)lem. Futuie work may provide an 

 adequate solution, but at present we have little but sugges- 

 tion to olTer. 



• 



Misleading Factors. 

 In approaching this ([uestion scicntificallv there are some 



