FACTS AND THOUGHTS ABOUT LIGHT-EMITTING ANIMALS. 225 
SOME FACTS AND THOUGHTS ABOUT LIGHT- 
EMITTING ANIMALS. 
By Professor P. MARTIN DUNCAN, M.B. Lond., F.R.S. &c. 
[PLATE VI.] 
A FTER the glare of daylight has passed into night, during 
the warmest months of the year, countless little points of 
light are often to he seen on the turf and amongst the brake 
and underwood in the open country of the South of England. 
The light is distinct enough, and when scattered far and near 
over a hillside, is always a matter of wonderment to the ob- 
server who witnesses the sight for the first time. When 
curiosity impels anyone to approach the little luminous points 
more closely, their 66 phosphorescent ” gleam is evident enough, 
and the greenish white light glows. It increases and diminishes 
in its intensity, becomes bright and fades in a surrounding 
mistiness and again flashes out more brilliantly than ever. 
Hour after hour the green and white illumination persists, but 
if any one point be carefully watched, it will be observed to 
cease occasionally for a second or two, and often to move about. 
Towards the darkest hours the luminous points become more 
numerous and brilliant ; but midnight witnesses the paling of 
the light which “ fadeth at the crowing of the cock.” 
Searching amongst the grass for the cause of this remarkable 
light, the hand feels no increase of temperature on approaching 
the objects which relate to it, and successful seeking discovers 
a cold, softish insect. 
At the same time of the year, when the summer’s sun has 
warmed the surface of the sea, the darkest nights during calm 
weather off the coasts of our Islands are illuminated by fitful 
flashes of green, yellow, blue, and rarely red light, which, start- 
ing suddenly from one or two spots on the water, spread on 
all sides in coruscations, or in glowing ripples and increasing' 
breadths, to cease as suddenly as they began. A boat glides 
into some quiet, dark harbour and sets the sea u aflame ; ” every 
dip of the oar produces an extending circlet of light, every drop 
of spray is luminous, and adds to the sparkling as it falls, and 
NEW SERIES, VOL. III. — NO. XI. Q 
