534 
[September, 
Will-o* -the- Wisp again. 
was that of my own eye, but did not think of this at the 
time, or might have made the experiment of stooping and 
putting my face to the ground, which experiment I now sug- 
gest to others who may have an opportunity of investigating 
the mystery. 
None of the explanations quoted in the paper above re- 
ferred to are at all satisfactory. 
It appears to me that I was surrounded by a faintly lumi- 
nous waving mist, — its luminosity so faint that it was only 
visible when a certain depth or thickness was presented in 
the line of vision ; that at much greater depths than this the 
mist was opaque to such faint light, and therefore the lumi- 
nosity presented itself as a ring with an inner radius corre- 
sponding to the depth necessary to render it visible by 
accumulation, and an outer radius limited by the opacity of 
the mist. The dancing fluctuation was probably due to the 
unequal diffusion of the luminous matter. 
If this is correCt its visibility only at and about eye-level 
(the lights appeared about a foot in perpendicular height) is 
explained, as on looking obliquely downwards there would 
not be a sufficient depth of the luminous matter between the 
eye and the ground, and on looking upwards the region cf 
its diffusion would be penetrated, 
I finally reached the town of Viareggio, and there learned 
that I had taken the wrong road after leaving Pietra Santa, 
and the next morning I walked back and then struck inland 
over the hills. 
The absence of human habitations was fully explained. 
The road I had taken passed through a most pestiferous part 
of the Maremma, which is even more deadly than the 
Pontine Marshes, though of smaller extent. 
If the modern theory, which attributes the poisonous 
aCtion of the malaria to germs of bacili or bacteria, or simi- 
lar microscopic organisms, be correCt, this faint phosphores- 
cence is easily accounted for. We have only to suppose 
these to be like so many of the lower forms of organic life 
which are phosphorescent. The ocean is so filled with these 
at times that the wake of a steam-packet is a belt of light 
of at least a hundred times greater luminosity than that 
which I saw over the Maremma. 
It just occurs to me, in writing, that there may be some 
connection between these phenomena and the strange stories 
that are told of a luminous aura floating over death-beds, and 
which poetical people have attributed to the uprising of the 
departing soul. At the risk of being denounced as a mate- 
rialistic brute I cannot help suggesting that this luminous 
