LUMINOUS ANIMALS 
147 
interesting colony, he states: “ When a 
Pyrosoma is stimulated by having its surface 
touched, the phosphorescent light breaks out 
at first at the point stimulated, and then 
spreads over the surface of the colony as the 
stimulus is transmitted to the surrounding 
animals. I wrote my name with my finger 
on the surface of the giant Pyrosoma , as it 
lay on deck in a tub at night, and my name 
came out in a few seconds in letters of fire.” 
Mr. Bennet also tells us that on one occa¬ 
sion, when journeying in the Australian seas, he 
passed through an expanse of luminous water 
which he judged to be a mile in breadth. 
Casting a towing-net over the stern of the 
ship in order to investigate the cause of the 
illumination, he found that it was due to 
enormous numbers of Pyrosoma which gave 
forth a pale, greenish light. 
Many of the corals emit a bright light. 
Darwin, in reference to a species found on the 
coast of Bahia Blanca, tells us that: “ Having 
kept a large tuft of it in a basin of salt water, 
when it was dark I found that as often as I 
rubbed any part of the branch, the whole 
became strongly phosphorescent with a green 
light: I do not think I ever saw any object 
more beautifully so. But the remarkable 
circumstance was that the flashes of light 
