PHOSPHORESCENCE. 82 
that it suggests another possible cause. 1 venture to suggest that 
Phosphorescence may be caused by lingering vitality in nerve centres 
or ganglia; indeed, the whole network of nerves may still be con- 
veying feeble nerve current which exhibits itself in this particular 
way. I should think that the cases of Phosphorescence in decaying 
wood are usually due to the growth of bacteria or to the active 
mycelium of moulds. 
A word more about the so-called luminous mosses: The genus 
amongst which the phenomenon is said to occur is ScuisrostEGA, and 
S. PpENNATA is specifically mentioned as displaying luminosity. I 
have not seen it affirmed that the moss is luminous with absolute 
exclusion of light. It is believed to be more than likely that at 
certain times these mosses form small highly transparent refracting 
vesicles which concentrate what available light there may be in the 
vicinity. At the same time the observations may be quite correct 
and there are self-luminous mosses. 
I have reached a point in my paper at which I should like to ask 
the question: How far is it possible to form a working hypothesis 
which will cover most, if not all, the phenomena which have been 
detailed? Personally, I would look to Electricity as the chief cause, 
and for the following reasons: (a) It is the least improbable. Such 
alternatives as the secretion and oxydation of free phosphorus or 
phosphoretted hydrogen, the secretion of substances which respond 
to insolation, or the secretion or separation of substances of the 
radium class, are, to my mind, for reasons which I have not the space 
to enter into here, less probable than an electrical explanation. 
Pursuing this line of thought, the questions arise: (1) Is electricity 
formed or furnished by living things? (2) Can electricity produce 
any such appearances as those we have been dwelling upon ? 
The answer to the first question is manifestly, Yes. Galvani’s 
classical experiment on the nerves of a frog’s leg shewed clearly that 
the energy which causes the nerves to react on the muscles, thereby 
